MG Midget and Sprite Technical Engine Breather OIL SUCKING. Yet another engine. BBS discussion at MG-Cars.net

MG Midget and Sprite Technical - Engine Breather OIL SUCKING. Yet another engine.

Guess what this thread is about then? But there's a slight difference, in that it's NOT my SPRITE. Re-cap. Bought '73 rwa midget in November 2012. Drove back from London 35 miles, Oil level was low -- about min -- , black thin and old. Slight miss on No.3, but otherwise went well. "No sign of oil sucking". Whilst off the road for body stuff, I pulled the head to cure the miss on 3. Hg was leaking 3-4. Noticed that bores are 20+. Otherwise engine completely bog standard recon unit. Engine now runs well without missing and has good even compression on all 4. Before I went for the mot a month ago, I changed the oil. Since then driven in warm weather, NO OIL SUCKING. Last night the temp dropped lower than it has been since I started it driving it. This morning it was chillier than it has been, when I started the Midget and went for a drive. About 2 miles into the drive, BIG CLOUD OF OIL SMOKE from the exhaust, which cleared when the engine warmed up. All I've done to the engine is replace the hg and change the oil. It seems to me, that had the oil been fresh and the level full, when I drove it back from London in November 2012, it would have sucked oil. I now have THREE 1275 engines that suck oil in EXACTLY the same way. This is more than a coincidence. Of course, having not stripped this engine I have no idea how well it was put together, particularly with respect to the cam bearings, camshaft and camshaft retaining plate. I hadn't fancied pulling this engine apart, esp since it otherwise goes so well. But now I suspect I might be tempted to pull the timing cover off and have a gander at what lies within, to compare it to my other 2 oil sucking engines.

Lawrence Slater

If it never sucked oil before, then.a huge oil cloud out the exhaust because the wether got colder but the cloud cleared after it warmed up.... My 1st guess..... is the oil gauze in the timing cover tank is clogged up, missing or just needs replaced, with the temps lower and the oil cold and thicker, ... the oil mist isnt being trapped into the gauze where it gets resolidifed back into liquid oil and being dropped back into the valve cover, so the oil mist is by passing the oil gauze and heading to the carbs to be burnt... with warmer temps the oil is thinner and gets caught in the oil gauze much easier...thus why it goes away as the engine warms up and you dont see this during the summer 2nd guess ...Im going with a valve seal gone bad, and the oil pools on top of the valves and gets burnt when you start the engine several hours later 3rd ... guess is a broken/damaged piston ring or oil control ring Prop

Prop and the Blackhole Midget

Again Lawrence? Its sucking is it? Are you sure its not something you have done?

Dave Squire

I have not posted on my oil smoke post because I have been collecting info, so I'm going to post on yours !! To recap, I fitted an oil catch tank and have driven the car all summer and watched the dipstick and catch tank on every start - car has done about 4000 miles this year. the results....... the car burns some oil when driven at 'about' 70MPH. the car doesn't ever suck oil when driven gently. the car only sucks oil into the catch tank if I floor it, sometimes a little oil, sometimes the full 0.5 litre ( but never more) Solution - it's a crappy engine designed and thrown together by militant commie workers who hated people rich enough to buy a new car - fit a V8 ! Malc

Malc Gilliver

"sometimes the full 0.5 litre" That's a lorra lorra oil. And that's disappointing Malc. I wasn't entirely convinced, but was hoping your take off split via the manual petrol pump hole, would prevent it. If it's been doing it in the warm weather, expect it to get worse in the cold. Dave. I wrote EXACTLY what I've done to this engine. Clearly the problem was there all along, but only showed up when I put new (thus more viscous) oil in, and the weather turned cooler. This is just the same as with my other (sprite) engines for the last 30 plus years. Doesn't do it in the summer. " -- it's a crappy engine designed and thrown together by militant commie workers -- " Not exactly my conclusion Malc. lol. They couldn't have left the factory doing this, or the first winter and everybody would have taken them back. So something vital must happen on rebuild, or develop during the life of the engine. Given that I now have 3 engines all doing it, one of which "I" didn't rebuild, maybe I can find a common factor under the timing chain cover. Hi Prop. No comment, other than to say, read all the contents of all the previous threads. lol.

Lawrence Slater

A wonderful topic this! It splits readers very clearly into believers and non-believers. There is a certain religious fervour about it! Only those of us who have seen the light (or technically, lack of it due to the extensive blue clouds) know it happens and it isn't "condensed oil vapour". When my engine was dieseling on the oil it was sucking up I knew there was a real issue. Cold weather, higher viscosity, sump topped up raising the oil level and it can happen.

Graeme W

You can lead horses to water Graeme, but you can't make 'em suck it up. ;). I've stopped trying.

Lawrence Slater

Mawrence, the common factor appears to be the driver ... ???? :-)

Paul Walbran

lol Paul. Except that, I've never driven Graeme's or Malc's cars ;).

Lawrence Slater

or the one of ours which did similar things ... though none of the others ever have.

Paul Walbran

Exactly Paul. As I said earlier. If they all did it when they left the factory, they'd all have been returned. Hence something common to those engines that suck oil, happens when rebuilt. Now my Midget is driveable -- albeit sucking oil -- I can take both my sprite engines apart for comparative purposes, in the hope of seeing something in common. And now that I know the Midget's sucking too, I can compare them to that engine. But as I'm now getting long in the teeth, feeble in mind, and generally bored with the saga, I very much doubt now that I'll ever work it out. lol.

Lawrence Slater

Question: what is the diameter of the little hole in the nipple on the top of your valve cover? I ask that because I just experienced an "oil sucking experience" of my own. Fresh rebuild, runs great, fully broken in, got about 500 miles on the motor now and decided to run up the expressway to a car show yesterday morning. Drove about 5 miles at 70mph (at 4000rpm), the ambient temp was around 40F and the oil gauge starts bouncing ("WTF?"), so I pull of to buy gas and the oil level is below the dip stick. Of course, I didn't bring any oil with me (I think to myself), it has never burned oil before, and hasn't moved a bit in the 500 miles since the rebuild, so I bought some 10W40 Diesel oil (took 2 quarts) to get me the 15 miles to the show. The plugs were sooty, and the exhaust pipe was too (the plug electrodes were a perfect shade of light tan, but the rest was gooked over with burnt soot). Got to the show, won second prize (yay), bought some proper oil, 20W50 with ZDDP, and drove home with that safely in the boot, but drove 45 ~ 50mph this time, on back roads. Ambient temp was around mid '60s. Didn't consume a drop. One thing that I am going to check next: the nipple in my valve cover is larger than 9/64". I had noted that years before, but the engine always behaved normally like that so I hand't done anything about it till now. I'll stretch some tape over it and pierce a new hole the correct diameter and try again to see if that makes any difference! I don't remember if the UK cars got a charcoal canister vapor recovery system, if not, then you won't have that nipple, but a vented oil filler cap. In that case, I do recall the cap was supposed to be replaced annually, to prevent its seal wearing out and causing a too high air flow. One more thought: my engine had the "brillo pad" in the timing chain cover oil separator. But, we pulled that out during the rebuild and now the can is empty. Perhaps that made the oversized nipple hole more able to draw the oil out? Additional thought: my engine breathes quite a bit better now (ported head, hotter cam, triple angled valve seats, generously radiused throat inside the air cleaners), this all will create more suck at the PCV ports on the SUs than before, especially as sustained large throttle openings, like 70mph motorway cruising on cold mornings (more dense air). Norm

Norm Kerr

Hi Norm. I written WAAAAAY too much about this to rehearse all the explanations again here. I suggest a visit to the archives. But briefly. The hole in the rocker cover cap doesn't cause this. The mesh in the breather canister isn't the cause. Also a red herring is the better engine breathing. The carbs are constant depression. That's not the problem. They are all red herrings. What you wrote here is the key. "Drove about 5 miles at 70mph (at 4000rpm), the ambient temp was around 40F and the oil gauge starts bouncing ("WTF?"), so I pull of to buy gas and the oil level is below the dip stick -- " 1). The ambient temp means that the oil was 'cold', thicker, and thus drains more slowly. 2). Assuming you started off with the oil level at max, to have gone down to min, proves that you sucked up a lot of oil. I have talked before about the oil dripping from my exhaust tail pipe. Your engine might have been prone to this before. Did you have a properly connected and working PCV system prior to rebuild? If not, you won't know if this is a new problem, or a pre-existing one, being revealed. If you did have a properly connected and working PCV system prior to rebuild, then something you did in the rebuild has caused the oil sucking. The oil is fed to the timing cover from the end of the camshaft. It SHOULD drain, faster than the timing cover fills, so it shouldn't be possible to suck oil, only vapour. And yet, your engine DID SUCK oil. Welcome to the club. LOL. Did you replace the cam bearings? Do you have any pics?

Lawrence Slater

""""One more thought: my engine had the "brillo pad" in the timing chain cover oil separator. But, we pulled that out during the rebuild and now the can is empty. Perhaps that made the oversized nipple hole more able to draw the oil out?""" **** BINGO **** We have a winner... thank you for playing why my engine has an oil cloud burning out the exhaust on cold temp days That brillo pad, and thats exactly what it is, stainless steel without the soap to be more direct, is not there in the timing cover canister as a conventiant holding spot to to scrub your dirty engine, it plays a crucial roll . The brillo pad is loose expanded and fluffy like birds nest.... if the brillo pad becomes "RUSTY" clogged dirty or compressed ... it will no longer be able to do its job, also if the brillo pad is removed it definatly wont do its job The purpose of the brillo pad is to catch, trap, and confine small oil particals and convert them back into liquid oil that drains back into the timing cover, if the brillo pad becomes clogged and rusty the oil particals will continue up the hose and re coalesce to form a oil liquide mainly in bends and tight curves of the vent pipe Now if the brillo pad is removed.... Then there is nothing to trap the fine oil mist particals which in the cold temps are very huge as big as tears ive heard and because there is no blockage, and no internal heat inside the vent tube esp colder closer to the carbs the more pronounced it becomes but once fully warmed up, you will see a deep reduction in burning oil via the timeing cover vent hose The brillo pad is called the... gauze . Make sure that brillo pad is new stainless steel and NOT compressed in anyway open and fluffy and NOT clogged. And I think alot of these situations disappear LAWERANCE You.said this car sat for a couple years non started... id think on an old engine sitting that long with that much muck build up over the life time of that engine was more then capable of turning that brillo pad gauze into a hardened rock and explains your situation... have you removed the brillo pad gauze for inspection or replaced it with a new one? Prop

Prop and the Blackhole Midget

If you dont want to mess with the brillo pad gauze... then an oil catch tank will need to be employed between the carbs and the timing cover Prop

Prop and the Blackhole Midget

Hi Lawrence, The oil was fully warmed to temp before the highway (a good 10 min or so of low speed driving, and a pretty gradual run up to speed). Before the rebuild, I'd driven the car many times before at 65 or 70mph, over 15 years, and never lost any oil between changes. The PCV system was the same before as after, and works well (no leaks). The cam and bearings are new. The oil pressure is a very stable 60psi at all but dead idle, when it drops to 40. As far as I can tell, the only changes are: removed the brillo, increased the top end breathing, put in new bearings, replaced the crank with a fresh one (original diameter big ends) and increased the compression ratio. The valve cover nipple hole was too large the whole time. Norm

Norm Kerr

For oil to be lost from the crankcase there must be pressure behind it and air-flow to carry it. If both the top vent from the rocker-cover and the vents from either the timing chain cover and/or the push-rod-follower cover are unobstructed the crankcase will not be pressurised by CCC and the flow will be shared out equally and thus weakly. If, however, the top vent flows less well than either of the other two vents then CCC will cause leaks or a stronger flow through the largest lower vent - in most cases that will be the one from the timing chain case case. I think in the last marathon thread on this subject in which I could not understand the problem, I mentioned that it's the top vent that counts - either to atmosphere or to a catch tank or to manifold: it doesn't matter which. On the A-series I've worked on over the years in Austins, Morrises and Minis I can't remember this oil-sucking problem and they all had proper top vents. Mind you, they were all ancient. I think the most modern would have been a late 1970s Mini! If an engine does not suck oil for years and then starts, it just means the CCC and flow is great enough to carry oil while previously it wasn't. Suction and pressure alone will not move anything unless there is also flow. I don't know if that helps but I would suggest there was a BL design fault that only showed up once CCC reached a certain level, ie: when the rings start to wear or a valve ceases to seal correctly - a lot of CCC can be produced by pumping past a poor valve and through its guide on compression. Reinstate the old-fashioned top-vent system and I think all will be improved. (I expect someone has already said all this?!)

Nick Nakorn

CCC = ??? Im sure I should know this, but I started drinking a bit early tonight Thanks Prop

Prop and the Blackhole Midget

I think, I GIVE UP. Sure. Why not eh? The whole problem is caused by having a blocked rocker cover cap, and or, either no "brillo", or a blocked "brillo", or a partially blocked "brillo", combined with worn rings, on a freshly rebuilt engine. Oh yeah. that makes perfect sense.! Sorry? What was that you said Nick? " I think in the last marathon thread on this subject in which I could not understand the problem, I mentioned that it's the top vent that counts -- " Huh? " -- in which I could not understand the problem -- ". ???? Did you really say that? Well that says it all then, and it says it all for a large number of the comments about this. Hi Norm. I have written over and over again. When the oil is dead cold, it takes an amount of time to reach a certain temp, when at which point, the viscosity is just about goldilocks. (You know that story I assume). At that point the oil is sucked in LARGE amounts, into the inlet tract from the WHOLE timing cover (not just the breather can, or the small area in that, occupied by the wire mesh), which at that point, must be full of oil. As the oil continues to warm, it thins, drains from the timing cover more efficiently( drains faster than it fills), and the problem ceases. UNTIL the NEXT goldilocks moment. It doesn't happen in consistently hot weather. If it does, you have a DIFFERENT problem to me. You started your journey at 40f. Pretty chilly. So the oil was cold. Then after 10 mins you had the problem. It wasn't your speed. So you've elminated the PCV as it's the same and wasn't sucking before the rebuild. So SOMETHING, you did in the rebuild has started the oil sucking. Something you did, NOW causes the timing cover to fill with oil, FASTER than it can drain. OR, something you did, causes the timing cover to drain SLOWER, than it can fill. I'll BET, that when/if, you take off the timing cover, the small drain holes in the front main cap, are CLEAR. That might leave you with the conclusion that the oil is getting into the timing cover faster than it was before the rebuild. OR. You might decide that it's "blow by", caused by your new rings not being bedded in. Well good luck with that line of thought. :). I for one am NOT going to repeat everything I've already said, and discounted or proved already. As I suggested, read ALL the previous threads, THE WHOLE WAY THROUGH. I started this thread as much for my own ammusement and record, as for the benefit of those already versed in, and accepting of, the problem of oil sucking via the timing cover breather. I did so because I have added yet ANOTHER 1275 engine, to the now long list of engines that do it. As and when, and IF, I discover the cause or something new that's relevant, I'll post it. Meanwhile, for all those who are interested, and can be bothered to understand the issues and explanations, I suggest you start with the thread "engine breather". You'll find it in the technical Archives. :).

Lawrence Slater

No, not a blocked rocker-cover cap, an absence of a top vent or a blocked vent (pic from a MM website). CCC = crank case compression.

Nick Nakorn

Nice pic...I like, lots going on there Prop

Prop and the Blackhole Midget

Lawerance On the transvese engines and minimania has several kits.... they use a oil seperstor catch tank not on the timing cover but on the carb side of the block where there is a blub of metal for what was supposed to be a fuel pump that never came to be on the 1275 I wonder if you went the way of the mini and got your crank case vent from that location if that wouldnt solve the issue...if for no other reason then to take the timing cover out of play...at the very least it would give you some new clues and ideas and eliminate many others Prop

Prop and the Blackhole Midget

Hi Prop, et al. The PVC system on "SPRIDGETS" was designed (having evolved from just venting to air) by BMC to relieve crankcase pressure and route harmful vapours from the sump into the inlet tract. The final design from BMC on 1275 "SPRIDGETS" (I'm not interested in other cars ) was to vent from the "TIMING COVER" to the "Y piece" and into the twin carbs at the point of constant depression. It works reasonably well, and there is no evidence that it didn't work as intended on new cars, and no evidence that those new cars ever sucked 0.5 of a litre of oil up along with venting the crankcase. The question is, --- the question I'm asking! Why do quite a few 1275 engines in "SPRIDGETS" that use the PVC system described above, suck oil into the engine, once they've been rebuilt, even though they weren't doing it "PRIOR" to being rebuilt? To all other questions and comments, about using other methods of PVC, or suggesting other types of problems, or, blah blah, etc etc, blah blah, ---- ----- ------ I refer you to the answers I gave, and the comments I made, in all the other engine breather/oil sucking threads.

Lawrence Slater

Why is always a tough question...ive been there, and know what your experiancing it is a little discouraging when your asking one question and everyone else is dancing around the question 10 people, 14 differant answers Maybe you need to pray to jesus more...®¿® Haha Prop

Prop and the Blackhole Midget

LOL Prop. You might be right about prayers. Graeme said a number of posts back, -- "A wonderful topic this! It splits readers very clearly into believers and non-believers. There is a certain religious fervour about it!" So God. What's the cause? Please answer my question. Just the question I asked. I don't want to save the bloody world, bring about world peace, or irradicate starvation. I just want to know why the bloody engines I've got, suck f*cking oil into the carbs. Why doth my timing cover runneth over? LOLOLOL.

Lawrence Slater

I was thinking about this today and wondered if the combination of oil pressure valve and the oil filter bypass valve (integral to the filter and by definition changed every time you change the filter) was a plausible cause. My logic is any problem with oil pressure could be exacerbated by having a non genuine spec oil filter, so maybe when the car was new the oil filter(made to BMC specs) had the right flow performance and the right the bypass filter performance and every thing worked ok. But now we have pattern parts to unknown standards and the oil sucking is function of the filter ? Don't ask how I propose to test this.... Malc

Malc Gilliver

Malc I thought the filter bypass valve was in the filter head, no?

David Smith

The way I see it is this. If the filter or filter head is raising the pressure, as the pump sees it, then that oil pressure increase wouldn't be seen downstream. Hence it wouldn't cause an oil pressure increase at the cam retaining plate oil feed to the timing cover. So the high oil pressure, if it is responsible for an increased flow of oil into the timing cover, must be as a result of something that happens AFTER the filter/head. However, whilst I and most others reported high oil pressure, Norm doesn't. Norm says, -- " The oil pressure is a very stable 60psi at all but dead idle, when it drops to 40." Does this rule out high oil pressure as a suspect?

Lawrence Slater

David, I was reading Vizard, he mentioned the 'bypass valve' as being part of the oil filter - but I have been wrong before ! Lawrence, Maybe, but a filter valve problem does 'fit' with the problem, it would allow for a 'good' make not causing the problem and a 'bad' filter make causing a 'bolt on, bolt off' problem. Also, I didn't say it raises the pressure, just alters it. Does a good filter bypass at high pressure, so delaying the oil surge, does a bad filter bypass at low pressure allowing a large slug of oil through ? or is it easier than that - some brands bypass and some don't ? As a sad git I tend to buy filters in batches of 5, so i have only fitted one brand of filter to my AHS - maybe just refitting the 'problem' each time Malc

Malc Gilliver

I'm Pondering that Malc! I use the original paper filters on my Sprite, and always used to buy the original BMC filters. However, the Midget has a spin on, and it's currently an after market cheapo by the looks of it. But I still think if it's an oil pressure problem, it must be caused by a blocked gallery somewhere, rather than a blocked filter.

Lawrence Slater

Malc, Does it seem likely that fault replacements in both designs of filter and housing, the old paper, and the newer spin on would cause the problem? When the weather gets really cold again, to eliminate it, we could remove the filter complely for a run to see what happens.

Lawrence Slater

Question: what is the bypass pressure of that valve in the filter elbow? The only thing that bypass valve in the filter elbow does is allow the oil to go directly into the engine without going through the filter first. It should never open, except in the case of a fully plugged up filter, which would really be something. There are oil filters which do contain an anti-runback valve, who's job, when the filter is positioned on an engine so the flange is "down", is to hold oil in the filter when the engine is shut off so that on the next startup, oil pressure is reached quickly (no need to "pump up" the filter first). However, with the vertical position of the Midget filter, with its flange "up" holds all of the oil in it, in a pool, anyway, what would an anti-runback valve have anything to do then? Would its presence have anything to do with anything, or just there but not needed. Remember the issue is apparently oil pooling in the timing cover, which is AFTER the filter, after the crankshaft and after the oil running back down from the cylinder head and cam shaft is on its low pressure way back to the sump, by way of the timing chain. Norm

Norm Kerr

Id think norms 40psi oil pressure at idle (800-1000 rpms) should be considard high oil pressure...10-15 psi I would consider to be normal psi Prop

Prop and the Blackhole Midget

Whilst I think 'excessively' high oil pressure may be an issue generally, the figures quoted I don't think are the reason. I run 70PSI and 40PSI at idle. I did have the oil suck problem but its gone now. I don't really know the reason why!. I just changed the oil filler cap and the hose from carbs to the timing cover, but can't see these changes would make that material difference.( The original cap seemed clear and in good condition). Indeed I think this has been tried on other engines without any improvement. I did strip the engine partially last year to replace the cam and fit adjustable timing gears. All the various holes to the timing cover were fine and clear. The cam bearings are original but I did not replace them. The cam plate was slightly worn but the cam end float was within tolerances. I did clean the brillo in the timing cover but it was not particularly dirty. The oil used is Castrol 20/50.

Bob Beaumont

I agree the high oil pressure is an issue, and when I get my engines apart I'm going to try and find out why mine both consistently read circa 90 plus on start and never drop below 80 when running. There must be a blocked gallery somewhere and that can't be good. However, having said that, I've done over 100k miles with "high" oil pressure, so if I've lost anything it can only be power. The question is, -- does it cause the timing cover to fill rapidly with oil, and overload the drains in the main cap? Many -- but NOT ALL -- threads going back to the earliest I found, and coming forward to the more recent ones, mention high oil pressure. But it could be just coincidence. Just one more "fault" that occurs in these engines, but not one that really causes an issue. High oil pressure at the cam plate sounds like a good candidate, but examples such as Norm's lower more normal running oil presure, suggest it's not the sole cause, and may not even be a contributory factor. BTW Norm. Earlier I dismissed Prop ( :) ) for suggesting a fix via the old manual petrol pump outlet. Well in this "mission impossible", if you want a quicker fix, and don't mind not knowing the why of it, then we shouldn't ignore Tom Cruise. Or to be more accurate, we should remember Tom CRAUSE Illinois, USA . He bought and fitted the Mini mania ally block that mounts on the old petrol pump outlet, and fabricated his own oil can separator from copper plumbing parts. His last report in the last thread on this subject, was that his oil sucking days were in the past. And I reckon they still are. If I can't find out why, it's what I've said all along that I will be doing to resolve the issue too. But for the moment, I'm still persuing the cause rather than a "fix", however good I happen to agree that it is. Here's a pic of Tom's solution. Others have done something similar, for other breathing reasons. Tom, are you reading this? Is it still good to go? If I go that route, I'm not sure if I'll "tap" the timing cover as Tom has done, or cap if off, or fit a filter on it, and allow air to be drawn IN -- thereby reversing the flow. I'm sure it will work, BUT, that's NOT my quest, and that's why I dismissed what Prop and others, suggest as solutions.

Lawrence Slater

Hi Tom, I did buy one of those mini mania fuel pump hole breathers, but have never installed it because I realized they would only work on an engine fitted with a PCV valve. My car has the SU PCV (fitted to US cars from 9/'70 ~ 10/'74), so if I opened up the crankcase with one of those breathers I'd have an uncontrolled vacuum leak in my intake.* (like driving with the oil filler cap removed) The reason why I bought it in the first place was "just in case" if I had oil leaks after the recent rebuild. But, I have none, so it remains in its box (and then I realized I couldn't use it anyway, because of how my engine is ventilated, though I could change that if I had to, but I don't, so I don't plan to). * Recently, I said the air flow limiting orifice in the valve cover was 9/64", but I was wrong. The filtered breather in the oil filler cap on PCV valve equipped cars is that dimension. The orifice on the valve cover for an SU ventilated engine is 1/16" (quite a bit smaller, almost half the diameter). Maybe it would be interesting to measure the vacuum in the PCV hose when an engine is sucking oil, just to see if it was really extreme (IIRC, normal vacuum in an intake manifold is in the neighborhood of 10 ~ 15psi while driving, 20 ~ 30 on deceleration, so the PCV system would have been designed with these pressures in mind. If the vacuum in the PCV tube was, for some reason, much more than 15psi, that would be a clue if the cause of oil sucking was from being sucked, or if the cause was inside of the engine (like, oil pooling in the timing cover). Norm

Norm Kerr

Norm, Vacuum can't exceed -14.7 psi relative to atmospheric pressure or you are exceeding an absolute vacuum or running you car on another planet or in a hyperbaric chamber.

David Billington

Norm, the vacuum is barely measureable. See the other threads where I experimented. The conclusion was, a VERY low level of vacuum, once the timing cover is full, is sufficient to pull the oil up. Vacuum is NOT the issue. And don't worry about no having a PCV valve. You are connected to the constant depression area of the carbs, NOT the varying HIGH vacuum of the inlet manifold. So you don't need a valve. If you connect to the block, you will still be drawing the SAME air in via the rocker cover, down through the block, and out via the petrol pump take off in the block, as well as or instead of the timing cover. There WON'T be a massive air leak. So if you have a mini mania adapter, and holes in the block already, go ahead and fit it.

Lawrence Slater

PS Norm et al. For those interested in all discussions about all that's already been said about vacuum and other distractions, please see -- "Engine Breather and HUUGGGGEEEEE blue clouds !!" I've reactivated it just for you. :). Hopefully, that way this thread might remain a little more concise, with somewhat fewer repeats, and far fewer postings too. :).

Lawrence Slater

Bring back Front Wheel Bearings! The oil isn't pushed out under positive pressure, it's sucked out by the inlet manifold vacuum. Open ended rubber pipe from timing cover to atmosphere - not a drop! Connect it to inlet manifold (even with pcv) - gasping for breath in the pollution!

Graeme W

Hi David, Actually vacuum in inches of mercury can be as low as -29.92 (the atmospheric pressure on a normal day). An SU vacuum gauge (fuel economy gauge for mounting on vehicle dashboards) goes to -30" Hg. Hi Lawrence, The SU constant depression CV relies on a metered orifice on the other end to prevent creating a lean mixture. In the A series, that is the 1/16" diameter hole on the valve cover and a sealed oil filler cap to avoid a leak. If I opened up the fuel pump hole for an extra breather then the SU CV would draw too much air into the intake and lean out the mixture (and it would probably screw with the dashpot operation). If the oil suck ever happens to me again, I may consider changing from SU CV to a PCV valve and open up the fuel pump breather, but none of that ought to be necessary if the actual cause of the oil sucking can be identified, since my engine never did it before removing the brillo pad and increasing the top end breathing... Norm

Norm Kerr

Norm, I responded to your post where you mentioned psi which is different to inches of mercury. The conversion factor is 1 psi = 2.036 inches of mercury to 2dp at least.

David Billington

oops, got it now, thanks David! Correction of my previous post: Now that I have reviewed portions of the 500 or so long previous thread and have seen Tom Crause's cleverly done fuel pump breather set up, I understand how to use it with an SU CV system! Also, interesting that the SU CV system has been used on some other engines along with a ventilated oil filler cap (with its 9/64" filtered hole), so perhaps the smaller 1/16" inlet hole in the valve cover nipple is to reduce the amount of air flow over the charcoal canister or something, and nothing to do with the operation of the CV itself. In any case, the oil sucking, as Lawrence has so often pointed out, can occur with various set ups of PCV. What they all seem to have in common is: A series engine, cool ambient temperatures, occurs once and then goes away once the engine is fully warmed up. Either the timing cover does not drain fast enough, or the oil supply to that area is too great, when the sucking occurs. Later, the thinner, fully warmed oil can drain faster and eliminate the suck... Norm

Norm Kerr

Graeme. I agree with you. No vacuum connection, no suck. But it takes very little suck to ingest oil, once the timing cover is full. Norm said. --- "A series engine, cool ambient temperatures, occurs once and then goes away once the engine is fully warmed up. Either the timing cover does not drain fast enough, or the oil supply to that area is too great, when the sucking occurs. Later, the thinner, fully warmed oil can drain faster and eliminate the suck... " YES YES YES. EXACTLY Norm. :). No need to discuss anything else, and we can all concentrate on why it happens that way. :). Why is the timing cover filling with oil, BUT, only on SOME engines?

Lawrence Slater

A nice page on the oil system. http://www.nonlintec.com/sprite/lubrication/ Malc

Malc Gilliver

OK, going way back to my 1275 mini racing days (circa 1980), I used to restrict the amount of oil flow to the rocker gear by screwed a PK screw into the underside of the oil feed rocker post, then cut off the head. This leaves a small gallery around the thread of the PK screw to allow a much reduced flow into the rocker cover. A more sophisticated mod is to plug the hole with an aluminium plug and drill a small hole in the plug. Once the oil level in the rocker cover gets above the top of the guides, you will get lots of blue smoke !. One day I will work out a way of measuring the oil level in the rocker cover while driving at 60MPH. So why does it happen now - new oil pumps - oil that is vastly different to what the engine designers had, AND (now this is only a theory !), piston ring material designed for modern steel sleeve engines - not our cast iron bores leading to higher CCC ?. BTW - I have a 1275 engine that I rebuilt that has a lot of CCC and uses a lot of oil sitting under my bench waiting to be cured !. Tony The Classic Workshop Black Mountain Australia

A L SLATTERY

Sorry, but you've not understood the problem at all then Tony. It's NOT the oil in the rocker cover causing a problem. It's the oil in the TIMING cover. Hi Malc. That link has already appeared in a previous thread. Twas, I that posted it. ;). Very good it is too. :). Many thanks to Steve Maas Long Beach, California, USA, for writing it.

Lawrence Slater

My bad Lawrence, The main drain hole from the timing cover to the sump is about 5/8" dia if I recall, and about an inch above the crank, so when running there is supposed to be a bit of oil in there. There are one (maybe two) small drain holes through the front bearing cap, but these only drain the last of the oil after the engine stops (otherwise you would get a puddle of oil when you pulled the front pulley). So you are saying that more oil than would flow out through a 5/8" hole is getting into the timing cover, then into the breather can and being ingested by the engine in gulps ?. Oil only finds it's way into the timing cover from the end of the camshaft or end of the crank. So, as I see it the only solution is to increase the diameter of the 2 or 3 drain holes from the timing cover to the sump. It's been about a year since I looked again at my problem engine, so it might be worth pulling off the timing cover to check what could be wrong with gaskets around those two drain holes through the front main bearing cap. You did not answer my theory on the rings we buy today ?. Tony

A L SLATTERY

Lawrence, Did you ever come to any conclusion about the possibility that your front cam bearing was not flush with the front of the block, but was driven in till it was recessed? Was there ever a factory tool to drift the cam bearings into place, and did it have a shoulder to stop the bearing at the block face? For both the front main and cam bearings, it seems the oil pumped to them would have about equal chances of leaving fore into the timing cover or aft into the sump. But, if the cam bearing were flush with the block face, would the cam plate tend to block the path to the timing cover and force more of the oil leaving the cam bearing to go aft to the sump? Then the hole in the plate might meter the oil flow to the timing cover with less excess taking an alternative route to the timing cover. Charley

C R Huff

"The main drain hole from the timing cover to the sump is about 5/8" " Hi Tony. It's not a drain hole per se. And there's debate about it being either a pressure equalisation hole -- crankcase to timing cover -- or an oil overflow. Either way, it's height (top and bottom), relative to the entrance hole to the breather canister, means that by the time oil reaches that level, it's a little too late. There are 2 drain holes in the front main cap. They are almost certainly too small, but there is no way to enlarge them without weakening the main cap I reckon. You asked "So why does it happen now - ?" The answer is, I don't know. Rings? Nope. It's not down to blowby. This DOESN'T happen on some engines with WORN rings, and poor compression. Charley. Nope not yet. I keep promissing to 'completely' strip my spare engine, and get the timing cover off the one in my Sprite. Now that the Sprite is off the road, I'm close to that. But in the meantime, my Midget snuck up on me and started sucking oil. Hence this thread. Your questions and comments are pretty much the same ones in my mind. So hopefully in the next week or so, I can get down to it. -- After I've made/fixed some stuff in the house.

Lawrence Slater

Tony et al. I meant to load this picture to go with my comments about the "overflow/drain" hole in the block face. I'm trying to avoid too many pics in this thread. They've ALL been posted before in the previous threads.

Lawrence Slater

If the problem does not occur with engines with very bad rings, perhaps the blow-by through one bore is sucked up by another. For the problem to take place there must, must be CCC greater than either; atmosphere for a naturally vented system or, inlet tract pressure for an assisted system. So if the rings are not to blame one is only left with the valves and guides. If you are 100% certain that your valves and guides are 100% good and that your rings are 100% good at all temperatures then I think you need to check them again. CCC caused by blow-by and valve seating imperfections happens on brand new A-series race engines (they need up to 4 CCC vents) so I'm certain a mildly tuned or standard engine will need two good vents even on a perfect sunny, high-pressure day. The only way that an assisted system can suck oil is if the inlet tract pressure is sufficiently below CC pressure to lift from the oil level to the inlet manifold. The difference between sucking oil and not sucking oil could be a matter of fractions of PSI so a design fault could easily cause this if insufficient margins for changes in temperature and pressure were accounted for by BL. Even the bore of the pipework and the elasticity of the rubber and the weather could make the difference. I'd be inclined to make a restrictor near the inlet manifold so that the outlet from the timing chain case was effectively much smaller and add another vent at the top of the engine. I know Lawrence you want to know precisely where BL went wrong. Where they went wrong was not allowing margins of error - there is not enough ventilation at the top! I still don't understand what your problem with this is - just accept that BL got it wrong and fix it. Finding the exact cause would need a pressure-regulated environment, lots of pipe bore sizes and rubber elasticities of tube etc.. etc..

Nick Nakorn

Hi Nick. I refer you to all the comments and discussions already posted about your comments on guides/rings/valves etc. I'll just say this. Put a straw into an empty glass, and you can't suck up any fluid, no matter how hard you suck. Put a straw into a full glass, and you don't need to suck very hard at all to fill your mouth. The timing chain cover fills with oil, and the low level of suction from the PCV is sufficient to suck that into the inlet. To say more is just to repeat everything all over again. So I refer you to the other thread I reactivated. :).

Lawrence Slater

Lawrence, I know! That is precisely what I'm saying! A very small change in PSI can make the difference so there's no mystery - BL got it wrong! The pressure needs to be relieved at the top of the engine so oil does not fill the timing case.... aaaaahhhh I'm going to kill myself.... :-)

Nick Nakorn

Lawrence, I know! That is precisely what I'm saying! A very small change in PSI can make the difference so there's no mystery - BL got it wrong! The pressure needs to be relieved at the top of the engine so oil does not fill the timing case.... aaaaahhhh I'm going to kill myself.... :-)

Nick Nakorn

Fair point Nick. My oil problem went when I changed the cap and pipe. It must have made enough difference in PSI to tip the balance.

Bob Beaumont

Bob, you clearly had an oil problem, but it wasn't the same as mine. If it had been, then changing the cap and or breather pipe wouldn't have fixed it. I tried that more than once, and so have plenty of others with the SAME problem as my engines have. Nick. NO!. You're wrong. IT IS NOT CRANKCASE PRESSURE, that fills the timing chain cover with oil. Read the other threads. Maybe you'll get it then.

Lawrence Slater

I have no confidence that changing the cap and pipe was the complete answer. All I know was that the engine exhibited the same dramatic oil problem that has been described many times on the various threads. What it seems to demonstrate is that a little change made the difference. I suspect there is no silver bullet.

Bob Beaumont

Hi Bob. If yours was doing the same thing as mine, --- sucking a continous column of oil into the engine -- , then that oil had to have come from the timing chain cover, and it could still be on the brink. If that's the case, then that small change you made just tipped the "balance", and who knows, it may yet tip back the other way. Those small changes you made, don't "fix" mine or many others. And anyway, a small change is all that happens to my engines too, and all the others that experience the problem. Namely, the engines warm up and the oil with it. As the oil warms, it thins and drains more easily. I'm of the opinion that the engines with this problem are ALWAYS on the brink. I've proved that, with a trip to the pyrenees mountains. I wrote about it in your thread you might remember. Hot the problem stops, cold it starts again. The point is, that there MUST be an underlying cause for the timing cover to OVER fill with oil. There is no reason to have a timing chain cover that full of oil. The chain only needs a splash, not a bath. That's the crux of the problem.

Lawrence Slater

Now the weather is regularly cold enough for experimentation, it's time to reactivate this old favourite. I know you've all missed this, so here we go again, just in time for Xmas. :). As we all know, unless you vent the crankcase(CC), pressure builds, and amongst other things, oil is expelled from the rear scroll. Nothing new there. Also as we all know, on the later engines, a PCV system was introduced to do the job better, and also to avoid polluting the environment quite so much. Nothing new there either. Further to that, as most people are aware, some engines suck oil up the timing cover breather. Some of you may remember back in Nov 2013, Guy's rubber glove. He covered the oil filler neck with it, blocked his timing cover breather tube, and at circa 2000rpm his glove inflated. Chris of Octarine services, asked about measuring CC pressure. So I knocked up a home made manometer, and connected it to the timing cover breather tube on my '73 Midget, and blasted a column of water 6 feet in the air when I blocked my oil filler neck off completely. That was back in November 2013 when it was still off the road. In September this year, with it back on the road, I discovered my Midget ALSO sucks oil. Hence this thread. – Read the 1st post of this thread for more info, so this makes sense. Over the last week, with it being cold enough to suck oil regularly, I've resumed my experiments. I began by repeating another experiment that I did on my Sprite last year. I have 2 plastic mesh filled oil filler caps. One with a large hole one with a small hole. Refer to the picture here, and read the thread " Engine Breather and HUUGGGGEEEEE blue clouds !! " in the technical archive, from Post 30 October 2013 at 17:50:26 for the discussion that ensued. I normally have the filler cap with the small hole on the Midget. So I swapped to the one with the larger hole. This means that more air can enter (be sucked in due to pcv) FROM the outside, and presumably more gas and pressure can escape, TO the outside if excess builds in the top of the engine. The result was that MORE oil was sucked up the timing chain cover breather tube than usually is, when I have the small hole filler cap in place. This is evidenced by a longer lasting and denser cloud of oil smoke. I repeated it over a couple of days. Same results Conclusion. A more free flowing oil filler cap, results in MORE oil being sucked up. So I did some more experiments. But you'll all have to wait until after Xmas to know the results. I bet you just can't wait can you. LOL

Lawrence Slater

So a bigger hole in the oil cap produces more oil Now thats interesting... id have thought the opposite To me this indicates the the oil is being.pushed not sucked If the oil was being sucked, id think you would lose volume and less vac with a bigger vent hole Drill the oil breather hole out larger dia and see if even more oil oilnis pushed out Prop

Prop and the Blackhole Midget

on the top half of the photo the oil cap on the right (Midget?) appears to have (more/bigger) venting apertures just below the top of the cap whereas the oil cap on the left *appears* not to have these

Nigel Atkins

Difficult to see from the angle of the photo.

Dave O'Neill 2

Lawrence: Have an hour or so before i head out to candlelight service to i thought that i would update you on my attempted fix to this problem. You may recall that this summer i plumbed a Mini Mania fuel pump port crankcase breather system into the existing timinig'cover - to - intake manifold system. (i also installed a sump to monitor any oil sucking that might occur). I can now report that after more than 3,000 miles the sump contained oil only on two occassions. (and then only less that a quarter of a liter). And this occurred only when i drove 70 mph. Now i should also let you know that i have not driven the car with the temperature less than 50 degrees. But can tell you that this system seems to have worked for me...

Tom Crause

Hi Tom. Thanks for the update. I wasn't aware that you plumbed in a "sump" as well. Do you mean you have a sealed catch tank in the line, that you can inspect to see if any oil has been drawn up? Dave/Nigel. Both caps have side vents. The one from my Sprite, is more free flowing. Prop. The cap with the larger hole is more free flowing. If anything therefore you would expect the pressure in the crankcase to be less, as it can more easily be relieved via the rocker cover. This is effectively the often suggested solution to crankcase pressure. It's like adding an extra vent in the rocker cover. However, as explained below, in fact, the smaller holed oil filler cap, and hence the more restrictive cap, results in LESS oil suction. When I fitted the large holed cap, MORE oil was sucked up. Since the large holed cap would be expected to relieve the CC pressure more effectively, by virtue of being LESS restrictive, that would detract further from CC pressure being the cause of oil sucking. Time to quit for the time being. LOL. :). Happy Xmas everybody.

Lawrence Slater

It would mear drilling 2 1/4" holes in the timing cover, Why not create a visual oil level gauge with a glass tube, This will tell you the oil level while running. Sandy

SANDY

Lawrence, That is correct. My monitoring system consists of a pint sealed Mason Jar catch tank connected to the existing breather system by two clear plastic hoses. With this system i can see when the exactly when the breather system is sucking oil from the timing cover... Fortunately, that hasn't occurred much since i installed the Mini Mania breather...

Tom Crause

Hi Tom. When does it next get below 50F in Illinois then?. Below 50 should result in an oil suck if it's going to. That's about the ambient temp' when mine starts to suck. If when below 50 yours doesn't suck, that's the proof that it's working then, and as said before, if I can't find the prime cause, that's also the method I'll use to 'fix' it. I wonder if the oil you collected was actually thrown out by the spinning camshaft? I know the mini mania double drilled block is supposed to prevent this, but maybe it didn't. Hi Sandy. What you suggest is what I'm going to do do, except that I'm going to replace a much larger section of the front face of the timing chain cover with clear plastic. I'm even going to light the interior with some led lighting. Otherwise I wonder if it will just look like a black smeared swirling blur, in which it will be impossible to tell the level the oil reaches.

Lawrence Slater

Errr.... let's make an oversimplified statement: If the crankcase breather is connected to the induction on the inlet manifold then there is "vacuum" sucking on the pipe. If the engine was completely sealed, the vacuum would have to work hard. If there is a hole in the rocker box cover cap, it makes it's life easier, and the bigger the hole, the easier it becomes. No oil escapes from my breather unless I connect it to a pcv on the inlet manifold. The colder, viscous oil builds up in the timing cover until the breather is flooded and "whoosh" - London 50's fog emulation.

Graeme Williams

Im not sure I like the idea of a mason jar as a catch tank Lawerance ... I dont think there is much oil that high up that a viewing window would be of any usefulness, I think it would get splashed on and run off, put thats about it, maybe a viewing window several inches below the crank shaft on the cc sump pan could tell you what your wanting to know Prop

Prop and the Blackhole Midget

I still dont see how a bigger vent hole is creating more suction... thats why I think your actually seeing some kind of tempory pressure thats forcing the oil out till the blokckage is clearing the system at 50 degrees F. Then it snaps back to suction from pressure (Shruggs like atlas) ... I dont know. Prop

Prop and the Blackhole Midget

Prop, It's NOT creating more suction. It's allowing for an easier flow of gasses and oil. If the filler neck on the rocker cover is COMPLETELY sealed off, and assuming there are no other vents in the rocker cover or other holes above the head to allow air in, then as Graeme implies, vacuum would eventually be achieved and no air or oil could be sucked from the timing chain cover breather tube. However, that can NEVER happen, because the dip stick hole, and the rear crankshaft scroll allow air to leak IN. Could the air from these other 'inlets' be additive, in terms of pressure in the sump? BUT, there is NO doubt about it. The bigger the hole in the oil filler cap, the more oil is sucked up when the PCV is connected. It makes sense really, but IS THIS THE PRIME CAUSE? Could it be that originally, the oil filler caps were of such a restriction that, the fine balance of air flow down through the engine and up through the timing cover breather tube, was such that under ALL temperature conditions, no oil was sucked up? I don't think so. Prop. It is my contention that the oil in the timing chain cover reaches a HIGH enough level -- on some a-series engines , that it's inevitable that it is sucked up as Graeme just described. Hence I need a HIGH window to view the level, not a low one.

Lawrence Slater

And now for the result of a further experiment. I promised you more of these on Xmas eve, and I know you just haven't been able to sleep properly whilst waiting. lol. Regarding the subject of CC pressure being the root cause of the oil being sucked into the inlet tract. To continue the experiments involving swapping my oil filler caps (large hole/small hole), I COMPLETELY blocked off the hole in the oil filler cap on my Sprite engine, and left the breather pipe from the timing cover open to the air, with the end pointing into a tin can to catch any oil that might be expelled. Would the CC pressure rise sufficiently in the sump, to blow oil from the breather pipe into the tin can? I started the engine from dead cold, and went for a drive. I drove for about 10 miles or so, more than enough for the oil and engine temp to go through the stage where normally it would suck oil if the suction from the carb's were connected. Result? ---- NO OIL, AT ALL, in the tin can. NOT A SINGLE DRIP. So what of CC pressure then?

Lawrence Slater

Ah but, you say. Maybe pressure was escaping up the sides of the oil filler cap, or maybe my 'seal' was leaking. OK. So I did this, and got the same result. NO oil in the tin catch can after driving from COLD. So what of CC pessure?

Lawrence Slater

"Ah but -- ", you say. Maybe pressure was escaping up the sides of the oil filler cap, or maybe my 'seal' was leaking. OK. So I did this and went for a drive, and got the same result. NO oil in the tin catch can after driving from COLD. So what of CC pressure?

Lawrence Slater

I wonder, does it help to think around the RATE OF FlOW of air (fumes) through the system, rather than the pressure (or suction = opposite ends of the same thing, as it were). The rate of flow will depend on both the amount of suction from wherever the breather is connected to, plus the available sum total of orifices letting air into the otherwise closed crankcase. Large openings (oil filler cap + dipstick tube + rear crankshaft scroll + ??) will allow more air to be pulled in freely and the rush of air as it is pulled through the narrow opening to the breather pipe will speed up at that point. A bit like a broad river as it narrows to flow through a gorge or over a weir, and speeds up. This will increase the tendency to lift oil along with it, to the point that it fills the opening to the pipe and initiates the oil sucking phenomenon. Smaller total openings will restrict the volume of air moving through, and consequently produce a lowered pressure in the crankcase and possibly less tendency to start the oil suction. Rather counter-intuitive I would think. But there must be a balance point in the process between lowered pressure and increased volume of air flow. So a dynamic situation with other variables chucked in like temperature, engine revs, oil viscosity, oil pump capacity, leakage at the front camshaft bearing etc etc. Very complicated indeed to accurately model the total system and therefore predict when oil sucking will actually occur. Although the principle is simple enough

Guy W

Lawerance, I dont know... oil level that high up seems really out of the ordinary to me With the oil level that high id think the cranksaft counter wieghts and bottom of the connecting rods would be splashing and cavating inside the oil Maybe you have to much oil in the engine is the problem I think you maybe having an additional vent hole somewhere...with the cap sealed plus the rest of the engine sealed... then the engine should not even run...but if the vacume hose is disconnected and hooked to a catch tank...then your running to atmosphere, with no vacume or cc pressure To create more vac inside the engine, you need less air or more restricted air entering into the engine The more air or less restricted the air comming into the engine then the less vac you will creat, this is why im confused when you say using the cap with the bigger vent hole is creating more vacume...it should be less and why im taking a wild guess that your experiancing pressure and not vacume if the bigger cap vent hole is producing a larger effect Im on the road back home Talk to you in a few hours

Prop and the Blackhole Midget

Guy... I like your thinking....and I think definatly worth exploring the path your on. See you guys in a few hours Prop

Prop and the Blackhole Midget

Prop: "the cap with the bigger vent hole is creating more vacuume" It isn't creating more vacuum, but it is creating a greater volume of air flow and therefore more of a rush of rapid air as it enters the narrowed section of the breather pipe

Guy W

Doesn't it just mean the PCV is faulty? It's supposed to limit the suction when the throttle is closed, e.g. on the overrun. Only engines with suction taken from the engine side of the carb requires a PCV. Later cars have the breather from the carb taking suction from the air filter side of the carb. This configuration has maximum suction at wide open throttle so piston blow by is balanced against suction. On the over run there is no blow by and no suction so it balances. Taking vacuum from the engine side of the carb has a different balancing act where maximum suction happens when the throttle is closed and blow by is at a minimum. Hence the PCV has to limit (i.e. reduce) the sucking on the over run. If the PCV was not limiting the suction you would get a great deal of vacuum, hence a great deal of suction, hence, under the right circumstances, oil being sucked up. Rob

Rob aka MG Moneypit

I agree with all of that Guy. But I always come back to the same thought process. Originally, when the cars left the factory, they didn't suck oil. AND, even though they've been rebuilt -- bored out with new rings --, MOST Spridget engines STILL don't suck oil. You can find for example say, numerous 20+ engines, with standard or large valve heads, that don't suck oil. But there are also 20+ engines, also with standard or big valve heads, that DO suck oil. So there still must be something else going on, that tips that balance. Something in those engines that suck oil, that the non-suckers don't have (or do have). You may have seen my new camshaft picture request thread. The reason behind that, is that I've found a thread on Piston heads from 2012. The poster, -- David.D, -- describes his 1275 Midget sucking oil. He drove it for 30 years and 160K miles. It NEVER sucked oil. Then he changed the camshaft. It's sucked oil ever since. At 160K miles, obviously worn bores, it DIDN'T suck oil. Change the camshaft, and it does. He describes it sucking oil, in EXACTLY the same circumstances that I and others have reported. Start it from dead cold in cold weather, and at the goldilocks engine temperature, it sucks oil. As it warms further it stops sucking oil. On the advice of an mg specialist, thinking it might be blowby and hence CC pressure, he had it bored and new pistons, in an effort to cure it. It still sucks oil. Sound familiar? He emphasises, until he changed the camshaft, it didn't suck oil. And that keeps bringing me back to the way oil is delivered to the timing chain and cover. Why is it that some a-series 1275 engines, in spite of being rebuilt to the same spec as others, suck oil? There is a recurring theme in most of these oil suckers. The engine had been rebuilt. They've been rebuilt and rebored by a wide spread of garages/engine shops. Are they ALL failing to bore accurately and building the engines in a sloppy way? My gut says, there is an identifiable common factor. Rob. carbs with the Y piece, DON'T have a PCV VALVE. They are constant depression on acceleration and overrun.

Lawrence Slater

And so. What OF that crankcase pressure? How great is it? Making use of a lower reading pressure gauge, 0-10psi, I again sealed off the oil filler neck in the rocker cover, and connected the pressure gauge to the open end of the timing cover breather pipe. Again I started the engine from dead cold. Result? ---- After less than a minute at about 2000 rpm, the pressure reached about 0.5psi. I checked the rear of the sump and there was a definite regular drip of oil. The dip stick was also pushed up and out sufficiently, to allow the pressure to stick at around 0.5psi. I fixed/sealed the dipstick in place so it couldn't lift, and did it again. This time running the engine until it was up to normal temp. Result? ----- With the dipstick sealed, the pressure rose to a little over 1psi, and there was a more rapid drip of oil from the rear of the sump. I increased the revs to circa 3500rpm. Result? --- The pressure rose to circa 3psi and steadied. The oil from the rear of the sump was now a continuous flow, not a drip. The crankshaft is fed with oil. So it's not surprising that with no other way for the pressure to be relieved, oil is pumped out along the rear scroll. But driving the car with the oil filler neck sealed, and the breather tube pointing into a can, the dipstick showed no sign of lifting or oil being expelled, and there was no oil expelled from the timing cover breather tube. Clearly the CC pressure in my engine, isn't sufficient alone to lift the oil and push it out of the timing chain cover breather tube. And even if the pressure was sufficient, there would have to have been oil in the breather tube in the first place, for it to be expelled; -- -- just as it was from the rear scroll, which spouted oil due to the oil fed to the crankshaft. None of this really changes what I/we already know. For oil to be sucked up the timing cover tube breather tube, you need the suction from the PCV connection. Again though, unless the breather canister and tube has oil in it, no oil will be sucked up. It's not caused by CC pressure. As has been said many times, ALL engines, even new ones, have CC pressure. Some have worn bores and more CC pressure than other engines, and yet they don't suck oil. My next step is to modify a timing chain cover and experiment to see how it fills with oil, or rather how high the level reaches.

Lawrence Slater

Lawrence, To me it doesn't point to a single cause across all engines at all. The fact that the condition that results in oil sucking is a compound of so many factors interacting suggests to me that the condition can be triggered by any one of many factors in different engines at different times. It seems to me that, were you a doctor, you would be looking at the records of a lot of broken legs and trying in vain to prove that they were all caused by tripping over a kerb, just because that is how one was caused. And, the position of the Y type pick up doesn't give a constant depression. On over-run the butterfly closes and the engine suction is sealed off from the throttle venturi. But agreed, they don't use a PCValve, as Rob was saying

Guy W

Guy. At the PCV take off for the breather, the depression is more or less constant. The dashpot piston rises and falls, and ensures that is the case. All of those factors you mention are present in all our engines. However, not all suck oil. The engines that do suck oil, have it's my opinion, an ADDITIONAL factor.

Lawrence Slater

Yes, all of those factors (and more!) are present in all of our engines, but many of them are variable, changing continually and interacting in a dynamic way which would make it almost impossible to determine an individual cause that one could confidently say was the trigger on every case. It doesn't of course necessarily prevent you from tracking down a cause for your individual circumstance.

Guy W

But that's precisely the point Guy. It's 'not' my individual circumstance. My engines share an additional common factor with the other engines that suck oil. Reference the camshaft picture thread. Dave has confirmed what I expected. The journals on all the camshafts are the same. Hence when 'David D' changed his camshaft, something else must have changed at the same time, that started his engine sucking oil.

Lawrence Slater

Well... im back home finally Lawerance ... you may have stumbled onto something, On your above test that you did today, you said you sealed the engine up very tightly ...even the dip stick tube and managed to only 1psi and drove the car at 3000rpm and got around 2psi What I find surprising is the car/engine actually even ran beyound 20 sec. If I did that to my engine, it wouldnt run.but just a few sec. It needs a source of air. I think.if you find the source of your air leak thats allowing your engine to continue working under your test enviorment, then you may find the source thats allowing extra sucking another observation worth noteing.... the vac at the air filters is around 2-3 psi, so if your measuring only 2 psi of pressure with a sealed engine... then you could be running a truely neutral "0" engine Prop

Prop and the Blackhole Midget

Prop. Have another read. :). a). I didn't drive the car with the pressure gauge. I just ran the engine at various rpm. b). At 3500rpm I got a reading of circa 3psi. c). You're confusing the combustion chambers with the rest of the internal engine. They are seperate spaces. My engine was still drawing air into the combustion chambers via the carbs, so it would run for as long as there is fuel. But it was NOT drawing air into the crankcase via the rocker cover filler cap. With the timing chain cover breather tube sealed with the pressure gauge, the engine would only have been expelling air/gasses. Hence the flow of oil from my rear scroll, and that's why I didn't drive it However, I did one more experiment. Previously (see below), the oil filler cap was swapped between a large and small hole version. The large hole version resulted in MORE oil being sucked up. So what if the cap were sealed off completely for maximim restriction, with the PCV system connected as normally? No, or reduced oil sucking? I kept the rocker cover filler neck sealed completely. I refitted my twin SU carbs to my Sprite. I did this because they are the most reliable at sucking large amounts of oil out of my timing chain cover. You may remember we discussed if the twins exert more suction at the breather take offs, when compared to the single breather take off on the HIF. I thought they did, so for a clearer result, I wanted the PCV connected to the 2 take offs via the Y piece. The consequence, is that the only air entry for the PCV system, is via the rear scroll, the dipstick, and maybe the front oil seal in the timing chain cover. Again, I ran the engine from cold. I ran it all the way up to 180F on the gauge. ++++ NO OIL SUCKING +++++. However, I only ran the engine in the garage, and the car hadn't stood overnight. It had been about six hours since it had been started, but often it needs an overnight before it's cold enough to suck oil on warm up. So on the next cold 'dry' day (no roof fitted) I'll go for a drive and see what happens. Let's suppose that this works. I.e. it stops the oil sucking. Is it a good idea to run the engine when the PCV system is drawing air in via the rear scroll and the dipstick? Unfiltered air being drawn in along the rear of the crankshaft rear main journal? it doesn't sound good to me. But if it does result in no oil sucking, then maybe there's scope to gradually restrice the oil filler cap hole. But this ignores the possible dual role the vent in the oil filler cap has. That of allowing top end engine pressure to vent off via the rocker cover. It may stay dry today, so I'll post the result if it does. Meanwhile. NORM. Are you present? Have you done any investigations to determine what's happening to cause your oil sucking?

Lawrence Slater

That's quite interesting. It rather supports my supposition that the oil sucking is a response to the VOLUME of air being pulled up the breather pipe, rather than the amount of vacuum generated - which we know is actually very little at around 1 to 3 psi. As regards the unfiltered air - I doubt that any air being drawn in past the rear crank scroll would result in any debris in the crankcase at all. Any minute particles that might fit through the clearances would be trapped by the oil film on the crank and maybe that would be more of a problem! In fact if the rear scroll was the only entry point for air one could imagine the oil being sucked back into the crankcase to the extent that the rear crank suffered a lack of lubrication! So maybe a small amount of air does need to come in through the filler cap after all, and anyway this will help to purge fumes from the rocker cover on the way through.

Guy W

There are two drain holes in the rear main bearing cap, so any air being drawn in would find its way through there, rather than being drawn through the bearing. There should also be somewhere between 20 and 70 psi of oil pressure, so the small amount of vacuum is unlikely to affect the lubrication of the bearing.

Dave O'Neill 2

It may be recalled that I had the oil sucking problem which went away when I replaced the oil cap(with small vent hole)and the pipe from the timing cover to the carbs. The original pipe was very old and had expanded quite a bit and had a greater internal diameter than the new one I fitted. The caps looked similar but the original was years old and I had washed it out several times in petrol. I wonder that these changes were sufficient, as Guy has suggested, to reduce the volume of air being sucked and hence oil.

Bob Beaumont

If that's all you did Bob, and that stopped your engine sucking oil, then it's hard to challenge that explanation. It must have had the desired effect. I tried those things though on my engines back in the 1980's, and it didn't stop mine sucking. I wasn't aware at the time of there being different sized oil filler cap holes, but I've shown subsequently, that even with the smaller hole, mine still sucks oil. -- Albeit that the density and duration of the following oil smoke cloud is altered a little. It's clear that if the flow of air and gasses is restricted sufficiently, oil simply can't be sucked up. The extreme case is, disconnecting the breather pipe from the suction. In that case there is only CC pressure to move the oil out of the breather tube, and on my engine at least, I've demonstrated that CC pressure alone is not enough. But is there an achievable level of suction/flow that won't result in suction? A couple of posts back I described my 'in garage' experiment with the PCV connected and the rocker cover oil filler cap sealed completely. Effectively no vent at all in the oil filler cap. NO OIL SUCKING. But I wasn't sure if the engine and the oil was cold enough. So an hour ago I went for a drive after leaving the engine a full 24 hours. Result? -- USUAL CLOUD OF OIL, AT THE SAME TEMPERATURE as shown on my temp gauge. I pulled off the seal on the oil filler cap, and the cloud did get a bit bigger/denser when I drove off. So again that confirms that, the less restrictive the air inlet, the easier the oil/gas moves through the system. I suppose it's obvious really. And, I'm not really surprised my engine still sucked oil. There's oil in my tube, and suction on the end of it. Put a straw into a cup of water and suck sufficiently, and what else could happen, other than you get a mouth full of water? If the glass was empty you couldn't suck up water. Likewise my timing chain cover breather tube. If it was empty, the PCV couldn't suck up oil. Nothing else left to measure/test. Unless someone can suggest something else. So the next phase is an observation window in the timing chain cover, to see the oil level.

Lawrence Slater

Lawrence, I've been neglecting this thread since my last post. Having read through all postings I now realise you have breathing to the carb constant depression region so my comments were erroneous. Having read through all posts high oil pressure has been mentioned. Many things have improved since the 70's. Machining is more accurate, I dare say big and main bearings are made to modern tolerances, oil pumps are probably better as well. Certainly, oil is much better than it used to be. All this points to oil pressure being sustainably higher than in the past. The oil pressure relief valve must be passing more oil into the sump to produce the gauge pressure we see today readings which are moderately higher than in the past. Where on the inside of the block does this oil vent? Is it possible it could in some way end up being directed as a jet towards the timing cover drain hole? at the goldilocks point? Just a thought. BTW I've been re-cycling old engine oil lately. See image. Rob

Rob aka MG Moneypit

Hi Rob. Yup high oil pressure is often mentioned by those with the sucking problem. But not everybody has both. Some people have normal oil pressure, but otherwise describe precisely the same oil sucking signs. Where could the excess pressure vent? Oil is delivered under pressure from the front end of the camshaft, directly into the timing chain cover, to lubricate the chain and sprocket. Maybe too high pressure results in too much oil. But the theory falls down when you consider those with oil sucking whose engines are running at normal pressures. Anyway though, I remain convinced that the root cause, is in too much oil in the timing chain cover.

Lawrence Slater

So where does the pressure relief valve dump it's oil? The one that regulates the pressure from the pump, next to the oilpump to filter head pipe at the rear distributor side of the engine. Is it piped to dump down towards the sump and by some quirk of circumstances some of the dumped oil is directed forward towards the timing chain area? It doesn't seem likely but oil is very peculiar under pressure and we may be looking for a 1 in a million set of circumstances. Rob (still re-cycling old engine oil)

Rob aka MG Moneypit

Could it just be something as simple as a worn front cam bearing, with too much clearance? That could explain why the guy who changed his camshaft suddenly experienced 'sucking' - the front journal may have been slightly undersize. When ever I've had cam bearings replaced, the machine shop have asked for the camshaft, so they can ream the bearings to suit. Too much clearance between journal and bearing may be allowing the timing cover to fill with oil, until the point that the oil heats up and drains faster.

Dave O'Neill 2

All - apologies for only now making this contribution, but I have just realised that my car stopped creating a HUGE cloud of oil smoke when I changed the rocker cover (and hence oil cap) earlier last year. This hadn't dawned on me before and I guess it corroborates Bill's story that a different oil cap/breather can make the difference? My old rocker cover was an original pressed steel affair with a black cap. My current cover is an alloy item with a red cap. Hope the above is of interest to those following this thread.... Glynn

Glynn (1275RWA) Williams

Glynn Does the new cap have any sort of breathing?

Dave O'Neill 2

Exactly my thoughts Dave on the camshaft, which was why I asked you for those cam journal pictures. I was hoping that there might be a visible, if subtle, difference in the oil delevery grooves. If he had a bog standard cam, and no oil sucking, and then changed to a later cam with a different degigned journal in respect of the oil grooves, that could explain it. But he doesn't say. Only that before cam change -- no suck, after cam change, oil suck. Of course there are other things that are likely to have been changed at the same time, even if not the bearings. Oil, cam endplate for 2. As regards the bearings. It seems that most people don't change the bearings. But if they do, and use the split type bearing, as you say it's usually reamed to obtain the correct journal/bearing clearance for a particular cam journal. But according to the specs, all front cam journals across the range are the same size. One thing I wondered, was if a reprofiled cam was used, would the machine shop also have polished the journals, possibly making them undersized? You can get cam bearings in STD and + sizes for ground cam journals. My old split type, the one I removed from my engine, is an STD size (as marked on the back). I measured my journal (unworn section) and it's on spec according to the WS manual. 1.666". The 'worn' sections are so close to that, as to be the same. When I stripped my engine, front journal/bearing clearance was one of the 1st things I checked. It was according to the book, about right. But if you recall, I also noted that my cam plate was distorted, oil was seeping from the sides and not only as it should be, from the delivery hole. I'm about to strip the front off the engine still running in the Sprite. So I can make some comparisons, and maybe find a common but incorrect factor. Edit. Glynn. As you can see, even with a fully sealed rocker cover, mine still sucks oil. Your falls into Bob's category of sucking then

Lawrence Slater

Rob. That is one of the things I'm still checking too. Where does the extra oil vent to? Is the pressure gauge misleading? Although mine reads very high, is in fact the pressure in the oil gallery, never more than 60psi?

Lawrence Slater

I haven't seen a used cam plate that doesn't show signs of wear in patches, between the mounting holes. I think it's a case of 'they all do that, mate'!

Dave O'Neill 2

I think you're right Dave. But I'm not so sure they are all distorted so that they don't lie flat against the engine front plate -- as mine didn't. As we still have a couple of months of suitably cold weather ahead, -- I assume -- and I have a spare car, I can use my currently sucking engine to play around. Swap camplates, fit a mask over the oil delivery hole to partially obscure it etc etc. I'm also going to pay extra attention to the cam endfloat. If too great, then cam can move further back into the block, and in that case the oil doesn't have to await the coincidence of the plate oil delivery hole with the groove in the journal. It will flow constantly, like an open tap.

Lawrence Slater

Dave (O'Neil) sorry to be a bit slow to respond but we've been out for a family lunch and I've only just seen your question. I was fairly certain that the new cap had a breathing facility but I've just checked and yes, there is a small hole in the base, approx 2-3mm diameter and what looks like an outlet just under the rim, where the cap seals to the rocker cover. This might be less breathing than the original? Glynn

Glynn (1275RWA) Williams

Hi Glynn. Which previous thread did you describe your engine's oil sucking symptoms in? I'll have a search for it. No need to repeat it all here though, it'll just make it another long distracting thread, that some people don't like ploughing through. -- Unless you really want to that is :).

Lawrence Slater

Ah don't worry Glynn. I found you. "Since I got the car on the road, it has suffered from low oil pressure when hot (~10psi at tickover, 40psi at speed) and burns a fair bit of oil when being driven and I hope to be able to fix both without taking the engine out.... " You ended up deglazing the bores, new rings and ends etc. Are you saying that you had a " -- HUGE cloud of oil smoke -- " , AFTER you rebuilt the engine?

Lawrence Slater

Lawerwnce you wrote... But if you recall, I also noted that my cam plate was distorted, oil was seeping from the sides and not only as it should be, from the delivery hole. Hmmmm....yeahhhh. I had a oil leak at the front that was notoius and took 3 years and a set of fresh eyeballs to finally figure out... warped front engine plate, and it was not that noticable with the naked eyeball, but a DTI told the tale. Id say if there is any distortion in your cam plate... to me that is a bingo moment to further explore My personal opinion if the oil is under 10 to 80 psi, it wouldnt take much for the oil to pass thur the distortion of the cam plate, esp if your cam bearing journals are worn...if im not mistaken arnt cam bearings supposed to be replaced with each new camshaft similar to replacing cam followers each time you pull them out. Id say, this is the area to explore for why your getting alot of oil in the timing cover I think if you can.see.the distortion of the cam.plate,.its time to replace not just filendown Prop

Prop and the Blackhole Midget

Lawrence - my oil clouds stopped happening BEFORE I carried out the internal re-work earlier this year. As I say, it has taken me a long time to realise, but with hindsight, I think it dates back to when I changed the rocker cover.... (Perhaps it was just co-incidence) Glynn

Glynn (1275RWA) Williams

Cheers Glynn. I'm not so sure Glynn. The ally cover won't have made any difference at all, unless there was a hole in the pressed steel one. That leaves the cap. Well as I've shown, reducing the flow into the rocker cover does reduce the flow of gasses and oil up from the breather. And your engine was abviously in need of attention. But was it actually sucking oil? You say huge cloud of smoke, but I can't find the thread you described that. I don't suppose you can remember which thread it was can you? How is your complete PCV connected now?

Lawrence Slater

Hi Prop. Read the "engine breather" thread in the technical archive, started by Bob back in 2012. Read my posts from -- 22 February 2012 at 18:11:57 UK time. That will answer all your questions and comments about my camshaft endplate. engine plate, and cam front bearing. Happy reading. :).

Lawrence Slater

I need the help of a beautiful assistant(s) now. But one of you lot will do as well. LOL. Actually Glynn, assuming you have the normal PCV into the Y piece, into twin SUs, then you'd be the perfect candidate, and the weather is perfect too. Nice and cold. If you haven't already started your Midget today, and hence the engine and oil are dead cold, would you please be kind enough to REMOVE the oil filler cap from your rocker cover? In theory, this could reverse the effect of your new oil filler cap, and even make it a worse situation. It would be very informative to find, that a non-sucking engine can be made into one that does suck oil, simply by increasing the air flow into the engine via the rocker cover. Method. Start the car, 'don't' let it warm in the garage or on the drive. Drive it immediately, normally, for say half an hour, and report back. If anyone else, whose Spridget has a complete and normally operating PCV system, and whose engine DOESN'T suck oil, wants to do the same thing, that would be very helpful too. PS. No point me doing it, BOTH my Sprite and the Midget suck oil already. Removing my caps, simply makes it worse.

Lawrence Slater

Lawrence, my original post was within one of your long running threads on this subject, some time ago. My report then was that my car would produce a large cloud of blue smoke, approx 5-10 mins after leaving the house. This would clear after a couple of mins of further driving. My oil breather is now routed from the top of the crankcase, through my inlet manifold water jacket and into the HIF44 itself. I can post a pic if required but I'm sure you've seen this setup many times. The original rocker could well have been holed or the oil cap in some way damaged? Glynn

Glynn (1275RWA) Williams

Ah yes Glynn. I think I remember the really neat plumbing now. I'll have a scroll back through the older threads, -- when I have a spare year or two. LOL. Into an HIF now. Was it on twins when you were still making smoke? I don't suppose you fancy my request then? ;).

Lawrence Slater

Hi Glynn. My false memory. I don't think I did see your plumbing through the inlet manifold, but I do seem to remember the description. Anyway, I have found your posts in "engine breather". At the time you said you cured the smoke by dropping the oil level in the sump. As Guy often makes me aware :), there may be numerous reasons for an engine smoking through the breather. And since neither of my smoking engines can be cured by blocking or restricting the air flow through the oil filler cap, I guess mine sucks and smokes for a different reason to yours. Although, I do think that if yours was actually sucking a column of liquid oil into the inlet tract via the timing cover, then there must be a connected component at work somewhere. And your engine could be perhaps finely balanced, between suck/no suck, such that a small change in the air flow was all it took to just tip it back to no suck.

Lawrence Slater

Lawrence - I WAS out driving the car for a half hour when you posted earlier BUT I had the oil cap in place! If I'm honest, I HAVE been wondering this afternoon whether it was the change to a single carb that actually made the difference but my ageing brain can't remember which happened first :( And YES, previously I reported that running with a lower oil level stopped the problem - however, I do NOT have to keep a lower sump level now, definitely. Regarding the fine balance between suck/no suck - that reminds me of an earlier time in my marriage, whereas NOW, it is definitely no suck ;) Glynn

Glynn (1275RWA) Williams

LOL. Well if changing to a single carb resulted in NO SUCK, then perhaps changing to twin wives, might result in SUCK?

Lawrence Slater

;)

Glynn (1275RWA) Williams

So lawerance.... What is the plan as of now...it seems alot of good stuff has been ran up the pole and then got shot down What do you think the top 5 reasons are for the oil suck??? By now, you have to have a working theory your playing with in the back of your mind, I just dont know what else there is to glenn from this bbs Btw... I have no interest in going back to the arcives, so ""BRIEFLY"" why is a warped/distorted camshaft cover plate not the problem for the timming chain cover to fill up with oil ?? I remember way early on several talking about dip stick accuracy, and it was decided that the oil level was not the issue, is the cc sump being to full of oil back on the table ? Props

Prop and the Blackhole Midget

What might help at this point, is to go back thur all the various threads that we have covered this issue on and just list ALL the suggestions for this oil sucking issue then list the reason why for each issue not being the cause Granted ... its time consuming, but it sure would provide a good map and may provide some interesting patterns that could lead to the true cause and the solution Otherwise... this could become the proverbial dog chasing its tail, ... and trust me, I know a thing or two about chasing your own tail Prop

Prop and the Blackhole Midget

Hi Prop. OK, just for you, about MY engine(S), briefly. The PCV sucks harmful gasses and water vapour from the crankcase. It's not supposed to be able to suck anything else. However, the route the breather sucks on, is via the timing chain cover. It's unfortunate that, the front camshaft journal is the chosen means of oiling the chain and sprockets, because it's my belief that the timing chain cover is being 'over'filled with oil, caused by a fault in my engine, and quite possibly other peoples engines too. This results in an inevitable amount of oil being sucked up with the gasses and water vapour. My top reason for oil sucking, as in MY engines at least? Too much oil in the timing chain cover. Why my camshaft endplate? The camshaft endplate, not only controls the endfloat, it also controls the main oil delivery to the timing chain cover (some is also fed in from the front crankshaft main bearing/journal). When I stripped my spare oil sucking engine, -- I have 3 of them -- I found that basically, it's cam endplate was bent. Thus instead of oil delivery to the chain being measured, I believe it was leaking in, in excess amounts. My engine front plate was also erroded, which I also believe exacerbated the problem. And, on top of that, my front cam bearing was recessed a little too far into the block and was scored to boot. Add all that together, and I 'think', I may have found the answer to why my SPARE engine sucks oil. Until I rebuild that engine with a new cam plate, engine plate, and front cam bearing, I haven't really got a clue. :). Meanwhile, much discussion followed, because numerous other people have oil sucking, but don't appear to have the same mechanical problems I found in my SPARE engine. Hence all the theorising about how and what else might be the cause, and exactly what the problem really is, in terms of it being vapour, blobs, or liquid oil. As mentioned, I have 3 oil sucking engines. 1 Spare in bits, 1 in my Midget, and the 3rd in my Sprite. They ALL suck oil in EXACTLY the same fashion. Since I have 2 'running' engines that suck oil, I can experiment, as per the posts in this thread. The next phase is to strip the front off the engine in my SPRITE, and inspect the camshaft endplate for similarities to my spare engine (above), and to devise a means of measuring the level that the oil reaches in the timing chain cover. It's all proceeding nicely to plan, albeit rather slowly, not helped by the fact that one needs cold weather to do the tests. Spring/Summer/Autumn are usually periods of no suck. :).

Lawrence Slater

"... not helped by the fact that one needs cold weather to do the tests..." No shortage of that, at the moment!

Dave O'Neill 2

Wow... there you go lawerance, Nice job ! I can certianly see your thought process now that you laid it out, and I think it has merit Sorry I was a bit prickly earlier... So really the problem boils down to the oil is not fully draining into the sump and getting cuaght up in the timing chain cover when the weather is cold...would that be a fair assesment Id be curious to see what happens if you drain a qt of oil off Another thought thats an easy work around is one of those "Kat engine warmers" they just plug in, several versions the 2 most common are dip stick warmer and the coolant warmer which you just splice into the lower radiator hose.... and makes for a toasty warm car 1st thing in the morning Ive used those KAT warmere thur the years off and on, im a fan...esp when the winter night time temps hit minus 10 to minus 20 below zero F. Burrrrrr Thanks for sharing your thoughts...now it dosnt seem so random Prop

Prop and the Blackhole Midget

Here you go, its the KAT lower radiator hose warmer These come in all sizes and wattages and are the most common here in the mid west just plug into the house electrical... granted you will need some kind of adaptor, its simple to install, might need some creativity, cheap, and depedable There is also the electric dip stick warmer... im not much of a fan as the rad hose warmer There is also a heating pad that you can attach to the oil pan, I dont know much about those but that looks real easy to install . I think something like the 3 I mentioned above would solve your problem without getting overly involved .... Quick, simple, and cheap fix.... something I know your a fan of. Its a midget, not a smithsonian art exhibit.... hahaha http://m.ebay.com/itm/121241649082?nav=SEARCH Prop

Prop and the Blackhole Midget

Here the type I use, the red KAT...agian multiple hose sizes and wattages available Agian not something I use every night, just when the over night temps get below 20F and it keeps the snow and ice off the windshild Im sure steven devine uses these as well, considering where he lives and owning a snow ploughing business http://m.ebay.com/itm/121048296777 Prop

Prop and the Blackhole Midget

My thoughts are never random Prop. Often mad, but never random. lol. Engine warmer? Yeah, I guess that would work.I could just use the car only in the warm weather too. HOWEVER, as I've said a zillion times. There may well be workarounds, - the additional breather connection on the side of the block being the best ----- BUT, I want to identify and fix the fault.!! Now that IS mad. lol. I've thought of another test. Some believe that oil is left in the pipe and breather tube when the engine is shut off for the night. It congeals, and when it warms, it is released as a slug of oil, to make the huge cloud. So it is thought by some. So I'm going to reverse blast air down the tube and breather to clear it, BEFORE I run the engine. I'll do that today.!!

Lawrence Slater

"Id be curious to see what happens if you drain a qt of oil off " Lack of lubrication, perhaps? The engine would need to be seriously over-filled for that to be the cause of the problem. As Lawrence has said, the problem is due to the amount of oil in the timing cover, not the sump, and the rate at which it drains when cold.

Dave O'Neill 2

Agreed Dave. Whilst it does seem to result in the oil sucking ceasing when the sump level drops low enough, that isn't much of a solution. However, I wonder why it should be the case, that a lower level of sump oil should stop the oil sucking? My best guess is this. There is less oil to be warmed through, and that makes it thinner sooner. As the sucking is temp/time related, I think that the faster the oil warms, the less chance there is for the timing chain cover oil level, to reach that critical goldilocks point. This makes sense to me, since in the warmer weather the oil is already warmer and hence thinner, and oil sucking usually doesn't occur; -- except on quite cold days in Spring/Autumn. And that brings me nicely to today's experiment. 1). I blew air down through the timing chain cover tube/canister/cover. There was very little resistance, which suggests to me that it was empty of left over oil, and the drain holes were clear. I kept my face over the open oil filler neck on the rocker cover, and felt the air I was blowing in, coming out at me via the open rocker cover. 2). I also wrapped pipe insulation around the timing chain cover separator canister. The fan blades were just scraping it, as I wanted it thick enough to insulate it from the cold air coming in from the radiator. I drove the car over EXACTLY the same route as yesterday, for EXACTLY the same distance. Oil sucking commenced at EXACTLY the same spot. 2.3 miles from home in my case. And then I consciously registered something; Something that I've also read in other peoples accounts of this. Oil sucking seems to be coincident with the thermostat opening. Why should this be? Here's my guess. The radiator is full of cold water. It's being blasted with cold air. The engine is encased in cold water, and cold oil is circulating through it. The engine is being warmed up, which heats the engine water and oil, but the radiator water stays cold, because it's largely isolated by the thermostat. The oil being fed into the timing chain cover is getting warmer all the time, and is draining at a rate sufficient to prevent over filling. Then the thermostat opens. Cold water circulates in the block, mixing with and lowering the temperature of the water in the block, and I reckon, suddenly lowering the temperature of the oil too. Is there a sudden temperature drop in the block oil, sufficient to thicken the oil, slow the oil draining, cause the overfill, and hence the oil suck? Last year I tried covering my radiator to keep the cold air from the front of the engine. It had no noticeable effect on the oil sucking. It still sucked. But I didn't have a hotter 'stat to try, so I didn't bother to try one. Suppose I had a hotter thermostat? Would the increased delay in 'stat opening, allow the block water and oil to reach a sufficiently hotter temperature, such that, when the thermostat did eventually open, although the block water and oil temperature would still drop, it wouldn't drop so far as to allow the oil to thicken as much, and hence the oil draining to slow down sufficiently, for oil sucking to commence? Glynn and Bob. What temperature thermostats are you using?

Lawrence Slater

88C model in mine

Glynn (1275RWA) Williams

Lawerance, Thats interesting....in fact that provides me with some ideas about my 1997 dodge truck... when its cold like now, the truck sort of stumbles briefly after about 5 miles after sitting all night cold, im using 20/50 oil because the engine has around 250,000 miles and the thicker oil fills in the gaps better.... But I think the same thing is happening, the stat opens releasing cold water into the cold engine block and rechilling the oil into a jello from a liquid, ... but if I let the engine warm for 10 minutes before driving ...I dont have the stumbling effect I think you have a real point Prop

Prop and the Blackhole Midget

You know lawerance.... If your latest theory is correct and I think it really could be...the oil sucking may not be a limited mechanical issue, it could well be a design flaw thats inherent to all 1275 engines or at least inline 1275s The reason this flaw effects one person and not the other may come down to just simple human behavior Think about it, how many of us actually drive our midget cars daily, then think about how many of us actually brave the the cold (30 F or below) to drive our cars ...not me! Thats for sure And of those that do, or even people like me that might fire it up 4-5 times when its super cold outside... whats probably the one thing we all do thats in common Yepp... warm that puppy up for a good 10minutes or so, or we have it in an insulate, perhaps even a simi heated garage I dont think ive ever just started my midget cold and took off driving with in secounds of turning the key, even in the heat of summer, I let the car sit ideling for a good 5 minutes before driving away I think your next experiment should not be engineering but a poll of social behavior, id ask who is sucking and who isnt sucking, then ask those that are NOT vs those that are sucking what is there cars sitting enviorment is like, and what is there starting procedure, and id ask who drives on a regular basis during the suler cold My guess is those that have there cars outside 24/7/365, drive them daily, thick oils, and just jump in turn the key, and are on the road with in 30 sec and the temps are super cold ... are the oil suckers People like myself that rarly drive midgets from november to april, leave

Prop and the Blackhole Midget

Then there are people like myself where the car is a garage queen, are rarly driven between november to april, and even then sit ideling for at least 10 minutes before we even pull it out of the heated garage when all the gauges show optimum driving specs Id lay good odds if on the next super cold day of leaving my car in the drive way over night, and just firing it up and be driving at 60 mes an hour as soon as it fires... I bet it would do the same thing as your experiancing And NO IM NOT DOING THAT...HAHAHA But ill take part of your new soon to come online pole. That sure would explain alot Prop

Prop and the Blackhole Midget

"My guess is those that have there cars outside 24/7/365, drive them daily, thick oils, and just jump in turn the key, and are on the road with in 30 sec and the temps are super cold ... are the oil suckers" Trouble is Prop. Nigel didn't drive his for weeks, and when he did drive it, it didn't suck oil. But there still might be legs in your thoughts. Glynn. I have a 160F stat in mine. Much colder. I feel another test coming on.

Lawrence Slater

"""Trouble is Prop. Nigel didn't drive his for weeks, and when he did drive it, it didn't suck oil. But there still might be legs in your thoughts.""" Thats true... but agian, what is nigels start up behavior and how does it compare to yours. What is nigels cars daily car enviorment compared to yours....in fact id even look at motor oil comparisons between the 2 of you, perhaps his engine bay traps more heat while yours may vent more heat The more I think about your theroy, the more I "belive, have faith" hahaha, that you may have nailed this one, it really does have merit If thats true... I think the oil sucking has to be the result of a driver behavior and not a mechanical issue Id love for nigel to provide his start up routine, how long he lets the car idle, what oil he uses, where he parks his car over night, the strength of his anti freeze, how heavy his foot is that 1st.10 miles ... what is the type of road he drives that 1st 10 min (contry dirt road or is it down town london) Then list your attrabutes for a side by side comparison....like guy said, its not one issue that cause the same break down, in that vain, I doulbt we all have the same start up and warm up procedure Im certianly differant then my father ...I like to start a car gentle and let it ideal to mid warm up before driving out of the drive, my father.. pumped lots of fuel, then turned the key and held the gas pedal down to some bizzare rpm range like 12,000 rpm for about 90 sec. Then drove out of the drive way

Prop and the Blackhole Midget

In my youth, Midgets were my daily drivers - snow, ice, whatever. I never got up early enough to have the luxury of letting the car idle before setting off for work. I never suffered from oil sucking.

Dave O'Neill 2

How about your stat rating Dave? Hot or cold?

Lawrence Slater

Whatever was in there LOL

Dave O'Neill 2

Well it doesn't matter, because it's official. I'm losing my mind. lol. I just had a read through last years long oil sucking thread. Last november(2013), in that thread, Bob told me he runs without a stat at all, but his engine has stopped sucking oil. AND, in the same section a little later, I wrote that I tried an 88c stat in my Sprite, and it still sucked oil. So I had a look in my cooling spares jar, the one where I keep things like spare rad caps and stats. And sitting there nice and quietly is a new looking, but used, shiny 88c stat. I don't even remember buying it. I had completely forgotten. My mind appears to be going. LOL. Well since I have an 88c stat, and my Midget engine struggles to get warm in this weather, I might as well try it in that as well. :(.

Lawrence Slater

I started mine up from cold a few weeks ago and just let it idle until it got fully warm, took it for a blast and it did not suck oil - just like yours Lawrence ! I have come to the conclusion that in my case the PCV is not reducing or limiting the vacuum being generated in the inlet manifold sufficiently. If I just get in the car and accelerate hard (high vacuum) it will suck oil, if I drive the car gently( low vacuum) it does not suck oil. Assuming (because I have replaced them all) the PCV diaphragm, all hoses are ok it has a new rocker box cap - the only PCV system component I haven't replaced is the spring inside the PCV. So answers and theories please on how a change of spring tension will affect the system. If a WEAK spring INCREASES the vacuum then we have a time/mileage based failure as the spring will weaken with time and heat. And a Happy New Year to you all !!!

Malc Gilliver

And on top of that Malc. I can say now, that fitting an 88c stat to my Midget, in place of an 82c stat, made no difference AT ALL! It still sucked oil, in exactly the same place. 2.3 miles from home. BUT. This has eliminated the thermostat/water temperature change as a factor. This time, when it sucked oil, the stat was DEFINITELY closed. AND, it STOPPED sucking oil, BEFORE the new 88c stat opened, bang on target at 190f -- gauge reading. Previously it started sucking at 160f. However the stat I took out was marked 82c(180f). So I chucked it in a pot of hot water with a thermometer, and it did indeed open at just about 160(72c). So clearly it was opening too early, but it had NO effect on oil sucking. That takes me back yet again to the time it takes to fill the timing cover, in relation to the starting temperature of the oil. Malc, I really don't think your PCV valve is to blame. I started with a PCV valve, and changed to the Y piece to prevent the oil sucking. But it didn't prevent it. So it seems I threw away a perfectly good, and these days, expensive PCV valve.

Lawrence Slater

I am surprised that you threw the PCV away Lawrence! I got the impression that you never threw stuff like that away "just in case", like most of the rest of us Spridget owners! LOL!

Guy W

Yeah, it's probably in the loft with your old gearbox!

Dave O'Neill 2

Wether the water temp is 160 or 210, once that warm water hits that ice cold water that hasnt heated up yet... it wont be 160 or 210 for long and I doulbt the oil will heat up all that fast if the temp is brutally cold Lawerance... how long do you allow the engine to warm up in the morning before charging full beonet up the hill ? Prop

Prop and the Blackhole Midget

Prop. I get in, start it up, and drive. Just like many an owner whose engine doesn't suck oil. That's the mystery. Why do some, and why don't others, irrespective of driving habit? Dave, sadly no, not there, I looked -- just in case :). Guy. In my defence, it was back in the earlier days of my Sprite ownership, when all these parts were more or less free in a breakers yard. And although already a keeper of used parts, I hadn't started then to hoard Spridget parts to any great extent. Especially as the PCV is such an ugly bit of kit, stuck on top of the inlet manifold as it is. The wisdom of age didn't bless me until a few year later. lol.

Lawrence Slater

Lawrence, without meaning to undermine your tenacity and research, which is impressive, I think you have long-since answered your own question. The reason it happens is an excess of oil in the timing cover, combined with suction (a modest "normal" amount is sufficient)at the breather hose. I think that is as much of an answer as you will get. The supplementary question of why some engines and not others is easily explained if you run up a list of all the factors that influence the delivery of oil to the timing chest, and all of those that influence the rate of drainage. Then add in the factors which determine how the oil behaves in the timing cover when the car is in motion. The full list will be long. All of these will interact together to influence the oil behaviour. And every car will have some slight variation in many of these factors. The accumulated effect will result in either an excess of oil in some cases, and oil suction, or not in others. I doubt that there is any single factor that applies in every case. Oh, and Happy New Year!

Guy W

LOL. Oh well, if that's all it is, I should have it worked out in no time at all then Guy. :). And a very happy new year to you too. :). Cheers. I can't decide if I'm going out to get drunk, or staying in to get drunk. Seen one pub and party on a new year, and you've sin 'em all. ;).

Lawrence Slater

Please dont drive drunk is all I ask Any chance.. redrilling the drain holes a tad bit larger would solve the issue....I cant imagine how that would work...because if it aint draining in 24 hours then bigger holes I cant imagine would have an effect Try parking on a hill with the front elevated Are you sure others start driving immediately after the car is started...might be worth exploring or at least polling Prop

Prop and the Blackhole Midget

Pub's a 5 min walk if I fancy it Prop, and I can gatecrash with my gf anywhere. lol. How about this? I only fill the engine with oil, --- in the summer?

Lawrence Slater

Gate crashing with the GF, hmmm.... how much of a hottie is she So what kind of club are you referancing... dance dance fever club, sports bar with chicken wing specials, of old fisherman bars filled with geriatrics gone to long at sea I just cant imagine you at a watering hole with the tenny boppers, gossiping about miley and kim K. Making out at a wreaking ball demolition site. Prop

Prop and the Blackhole Midget

LOL. No I didn't actually mean that, in quite that way Prop. I meant that if I wanted to gatecrash a party for ny eve, I wouldn't be going alone. But come to think of it, women are always a free pass to a party. I can recall a few times hanging around outside a great sounding party, and latching on to some bird or other. "I'm with her", you tell the door keeper if there is one. Or, if you're already through the door, you say the same thing, as you help yourself to a drink. Been chucked out a few times too though. LOL.

Lawrence Slater

Had a drive today to see how much water was leaking from my 'stat housing (see related thread on general -- "Thermostat housing. A Bridge too far?"). This gave me another exciting opportunity to see my engine suck oil. I wasn't sure if it would suck oil today, as it's pretty much like a warm spring day. But it did. Noticeable though, was quite how much EARLIER it sucked oil. Less than 1.5 miles this time, compared to 2.3 miles on a cold frosty day. Noticeable too, was that the duration of the oil suck, was I would say, a little longer if anything. Same dense cloud, but for a longer amount of time. Definitely the oil starts off too thick, when below a certain ambient air temperature. The faster it warms up, the sooner it sucks oil. Or more accurately, the less the initial temperature of the oil is below the 'goldilocks' temperature when starting out, the sooner the engine will suck oil. And of course if it's above goldilocks, it won't suck oil at all. I wonder what the critical temperature is, for the oil to be sucked up? And what exactly is happening? It doesn't suck immediately. Is it too thick to fill the cover, and the drains can cope? Or, does the fill rate remain more or less constant -- due to the feed pressure --, and the drains simply can't cope with the oil, until it warms suffiently to thin out and drain faster? Since I think the duration was longer, and the suck sooner, that suggests that the fill rate increased, before the oil was thin enough for the drains to cope with it. Then as the oil continues to warm and thin, the drains catch up, and the sucking stops.

Lawrence Slater

Guy: don't be a spoil sport! Pointing out what is now blindingly obvious (and has been for the last 125 posts) takes Lawrence's fun away! He is obviously trying to set the record for the longest thread in the history of the BBS having discovered FWB is now virtually dead. lol!

Graeme Williams

I've just spent a few minutes looking through the archives. Threads involving engine breathing probably exceed any other topic. It goes way back to virtually the start of the BBS. In many of them "oil in exhaust" is a common theme. I'm sure this thread has made readers much more aware of what is a common problem but hadn't been seen as such in the past. Some engines clearly don't suffer from it (and so many owners can't see it as a real problem) while others do. It is something my engine suffers from and I have been told it can't be due to flooding - it's vapour! On one instance when my engine was dieseling on the oil it ingested and spewing it out of the top of the pcv I found the idea of vapour hard to accept. So Lawrence next step: Royal Institution Christmas Lectures 2015?

Graeme Williams

1998 Graeme. 29 October 1998 at 17:55:02 UK time to be precise. I believe that is the first time here, or 'probably' on any bbs, that oil sucking was proposed. I joined a thread about too much pressure in the crankcase. I wrote --- . ---- "I have the oposite problem. I am getting too much suction. When my engine is cold nad hence the oil is less fluid, my SU's suck oil from the sump and deposit large amounts through the inlet. I dont have any cracked rings. It has done this since i rebuilt the engine with new pistons and a rebore. Help." ---- I expected that someone else MUST have had the problem before me, and knew exactly what and how to fix it. Although the replies were friendly and helpful, sadly no fix. I think I was misunderstood. So I wrote --- --- "Hi. Thanks to all for replying to my problem. Some more history. I am talking large amounts of oil here. I replaced the pipe from the timing cover with a clear pipe, and when the engine is cold it fills completely with a solid column of engine oil. The engine pinks and clouds of blue smoke fill the air. As soon as the engine is warm the problem subsides. I have tried restricting the Pipe from the timing cover to the y piece juntion where the pipe splits to connect to the body of the the SU carbs. No luck. My engine is a 1275cc with high comp pistons the same spec as CooperS. 19720 is I believe the Hepolite part number of the pistons. They have a shorter skirt and only 3 rings, as opposed to the 4 rings on the pistons I replaced. I have used a cylinder head from an Austin 1300GT which has larger Inlet and Exhaust valves. As I said I have had the problem since first assembling the engine. Compression is good and it goes pretty well, easily reaching max revs when first built. I have standard twin SU carbs for the 1275cc engine, with K&N air filters, connected to a standard inlet manifold. The breather pipe comes from the timing cover to a y connector, where it splits to go to a small pipe sticking out of the carb body, between the throttle spindle and the dashpot cover on each Carb. I have guessed that Either (1) I have too much suction with my engine setup, (2) I have too much pressure in the lower engine, but why I dont know, or (3) the oil is filing up the timing cover and not being able to drain away sufficiently quickly enough when cold and less fluid, and hence getting sucked right into the inlet. And that's the point it only does it when the engine is cold. When it approaches normal operting temp the problem goes away. Any comments welcome." ------ No more replies followed. ++++++++++++++++ Lectures eh? Sounds good. Maybe a special mention in MASCOT? How's this for an idea Graeme? We gather all the known oil sucking Spridgets together, on a cold sunny cloudless day. And then we perform a DRIVE BY. We could call ourselves the BLACK/BLUE arrows. Instead of a vapour trail, we could trail ??????? Now I wonder what we could trail? lol.

Lawrence Slater

Crikey, Lawrence. Over 16 years and you still haven't got to the bottom of it!

Dave O'Neill 2

Worse than that Dave. 1998 is only when I found the bbs. Before that, I used to plague BMC Oxford technical division for an answer, and every mechanic I knew, and plenty I didn't know. lol. I've had the problem since circa the mid '80s, and maybe before that, but it's so long ago, I can't remember exactly when. :-

Lawrence Slater

what helped for me 1) to reduce leaking was creating maximum breathing capacity. I modified the oil pan to allow blow by 2) to avoid oil in the intake a installed a oil - air seperator As I run a forced induction 1293 I had LOADS of trouble with 1) as well as 2)

a.o. arnold

No comment really I'm afraid. I'm not running forced induction, and I don't have an oil leak from the rear scroll. Does your oil/air separator also 'catch' oil, before it reaches the inlet? Or does it feed back into the sump? Do you have a picture of the complete ensemble?

Lawrence Slater

Before I went on the bridges run yesterday, and since I've been sucking oil daily doing these tests, I thought I'd better check my oil level. Just as well I did. I was down to just below min. Prior to the tests, I was at MAX. I know this because I checked before I resumed allowing it to suck so much oil. So I filled it to maximum. Yesterday morning I let the car warm up before I set off for the bridges run. So no oil suck. Did the run, and had lunch in the pub at Richmond. It was cold yesterday. But I hadn't expected it to be so cold that it would suck oil on my way home after I left the pub. Normally it takes far longer for the oil to cool enough for that to happen. But suck oil it did. And this takes me right back to the 1st post in this thread. Fresh oil in the winter, brings on an oil suck. So I would like to invite one and all with 1275 engines, who have the PCV system plumbed in and working properly, that DO NOT suck oil, to do a FULL oil change in this cold weather. Then go for a half hour drive WITHOUT allowing the engine to warm AT ALL beforehand, and then report back.

Lawrence Slater

Well I did an oil change in the middle of December, and in went a few litres of Castrol's finest 20/50. I have since used the car twice and don't bother to warm it. No problem to report. I know its not been that cold but in the old days I would have had the oil suck syndrome. Oil pressure was the normal 70psi. It runs slightly cooler anyway as I don't have a thermostat installed and have an oil cooler fitted.

Bob Beaumont

Cheers Bob. That elliminates yet another possible theory then. lol. Weired though, that my Midget, that I've had no hand in, in building or rebuilding the engine, should suck oil, but only start to do it, when I did an oil change. Now what could I possibly be doing to make it suck oil, by merely doing an oil change? Before oil change, no suck oil. Warm engine. Drain oil. Remove and replace old filter with new one. Fill to maximum. Start engine. Stop engine, let oil settle to check dip stick mark. Fill to maximum. End. Go for a drive, and suck oil. I used Motorway 20:50 this time. But I used to use GTX and all the other brands and still sucked oil. So it's not the brand or the quality. There just HAS to be something really simple going on here. How else can I have THREE engines that ALL suck oil in cold weather? I built 2 of the engines, but didn't build the 3rd. So if there's something being done in the rebuild, that causes the oil sucking, it's a mistake made by others too. Or it's a common component, that SOME engines get rebuilt with at some point. Or, it's an uncommon fault that only SOME engines develop.

Lawrence Slater

If your Midget engine only started sucking oil after an oil change, the old oil may well have been diluted with petrol, thereby thinning it sufficiently to drain faster. Solution: don't change the oil!

Dave O'Neill 2

New oil is going to have a higher viscosity than old oil, especially if, as Dave mentions, it has become diluted. Cold oil has a higher viscosity than warm oil. If the sump is at Max rather than at a lower lever, the oil will sit nearer the "suction outlet" in the timing cover. All of which increases the likelyhood that the oil is going to be more reluctant to flow back to the sump. Depending on other mechanical factors the combination of some or all of these factors floods the outlet connected to the pcv and....... trouble! In my case it was sensitive to oil level as I reported several years ago when I first plumbed in a pcv. For some time I had no problems and then topped up from about "half" to max. Whoosh! This thread does seem to go round and round in circles!

Graeme Williams

"Does your oil/air separator also 'catch' oil, before it reaches the inlet? " YES it does, if not I suck oil into the inlet. FI only make the crank ventilation more complicated PS I use a water / air seperator from a air compressor, but you beter use a real one, like this

a.o. arnold

Not that simple as just changing the oil though is it. As I've said in other threads, if not this thread, I used to always change my oil in the summer. Most people probably do. My Sprite doesn't suck oil in the summer, and nor does my Midget. My midget didn't suck oil when I drove it in the cold weather in November 2012. I thought my Sprite had stopped sucking oil because I had an HIF on it. But then I changed the oil in the winter, and hey presto, even with the HIF it started sucking oil. I wasn't expecting my Midget to suck oil when I changed the oil. But it does. However, as Bob just mentioned, he changed his oil in cold weather, and it didn't return to sucking oil. I was hoping that if a non oil sucking engine had the oil changed in the cold weather (esp one that had previously sucked oil), it would suddenly become a sucker(again). That would have perhaps solved the mystery, by suggesting that actually, ALL 1275 with our PCV system are potential oil suckers due to a design fault. But it's not noticed, because most change the oil in the warm/hot weather. But that's now been ruled out as the cause. The fact that my engines do suck oil after a winter oil change, is only due to, the so far unidentified 'fault'. I know the oil level in the sump contributes to the problem, but HOW exactly? If you hold a straw 1 inch above the surface of water in a glass, you would need an almighty level of suction to draw water into the straw. But the suction of a Spridget PCV system, esp the Y piece to the carbs, ISN'T that great. As I've shown before, the MAXIMUM level of oil in the sump, is SIX inches below the entrance hole to the breather canister in the timing chain cover, and over 3 inches BELOW the level of the drain holes in the main cap. There isn't a 'direct' contiunous connection/flow of oil between the sump oil level and the oil in the timing cover. So it's not clear at all how the level in the sump effects sucking, even though it does. But anyway, the sump levels, are common to ALL Spridget 1275 engines. So are all the other factors that are being proposed. And the trouble is, inconveniently, MOST engines DON'T suck oil. I've been giving some thought to all the 'factors', and I've come to the conclusion, that the 'multiple factors' theory doesn't explain it. Simply because for any of the known factors you care to mention, you can find an engine with them, that still doesn't suck oil. It's the unknown factor -- whatever that is -- that causes oil sucking.

Lawrence Slater

ao. Where do you get that purolator? Is it an obsolete item or is it still current? What car was it fitted to?

Lawrence Slater

"It's the unknown factor -- whatever that is -- that causes oil sucking" Perhaps it's Max ? ;o)

Dave O'Neill 2

this thread is really high lighting where the problem exist This is just ice cold super thick oil that hasnt heated up to a proper viscous in a sump that is filled to its maximum The solution is simple and only requires 3 simple modifications 1. Park on a hill so the front is pointing upward 2. let the engine warm up 15 to 20 minutes before driving. 3. draining off 1/2 qt of oil from the sump Based on the now 500 + plus postings over over several threads I think my above advice will solve the oil sucking problem This is a driving behavior issue, not a mechanical flaw issue Time to get off the round and round and round roller cage wheel. Jeff

Prop and the Blackhole Midget

Prop, 1,2, & 3 MIGHT be solutions to the problem BUT not a fix... If you want to get off the roundabout, be my guest. I for one will continue to follow with interest the efforts of Lawrence in full filling his life long ambition to prove beyond reasonable doubt the cause of the 1275 oil sucker... Lawrence, what happens if you use new 10W40 (or 0w30) oil? Also, I can understand how an oil pump may not have the ability to maintain the volume required when the sump level is lower than max. I admit it is maginal but lifting oil with an extra three inches of sump is easier than at the low point. however i would expect the pressure reduction curve to be higher ie oil warms up faster. Best of.... MGmike

M McAndrew

Jeff?? Who's that then? Dave, you may be on to something there. After all, we still don't know who killed her, and did you know, she was connected to "MAX" too? ;). Now I'll bet those lips, were a joy to 'suck' on. Even if you would have been sucking oil. Whale oil. :). PS. Mike. I tried 10:40 in the past in my Sprite, and it still sucked. Never tried 0/30 or straight 30. PPS. Experiments on my Sprite commence tomorrow. :).

Lawrence Slater

Whose jeff ??? Haha sorry about that, Jeff is the loser that part owns the flesh and blood body in the so called real world, I take over when it comes to driving, working on the midget and while on the net. Prop

Prop and the Blackhole Midget

Whose jeff ??? Haha sorry about that, Jeff is the loser that part owns the flesh and blood body in the so called real world, I take over when on the net. Prop

Prop and the Blackhole Midget

OK OK I think there is something in this now. (I read it all again over the last few days - phew!). After having the last engine leak fixed since recommissioning the car two years ago I am using more oil than I think I should and every now and then on cold days I can see it going out the back as a puff of smoke on hard acceleration when the engine is cold. Once the engine is warm there is no 'puffing'. I have three things not standard on the oil / breathing system. 1) My extraction pipes from the rocker cover to the carbs is hose pipe. The old rubber pipes were collapsed when I reinstated the car two years ago. The hose pipe was to hand, fitted, and was no problem at the time so I left it. However as Guy has pointed out the actual available flow volume is increased compared to standard pipes as the walls are thinner so they can carry more fumes and possibly oil / oil droplets. (A big river carries more sediment easier than a small river flowing at the same speed principal). There is oil in these pipes when the engine is off. 2) I did the 'John Twist washer insert' on the oil pressure relief valve as 1500's all 'wear out at the top you know' so I decided to make sure mine had lots of oil in the top particularly on start up and therefore when its cold. 3) I changed on this service immediately the leak was fixed from Comma 20w50 Motorway to Comma X Flow type MOT mineral 20w50 without thinking about it. So I recon I have now increased the internal pressure in the crank case anyway as there is no breather and no easy leak (I have a slight weep from the sump on one side and the rocker cover on one side - certainly not a leak), I have provided more oil in the top of the engine particularly when it is cold, and also increased the extraction above normal with the larger bore carb extraction pipes. Next service or sooner if poss I will return all to 'normal' and see. Makes sense?

Dave Squire

" My extraction pipes from the rocker cover to the carbs is hose pipe. The old rubber pipes were collapsed when I reinstated the car two years ago. The hose pipe was to hand, fitted, and was no problem at the time so I left it. However as Guy has pointed out the actual available flow volume is increased compared to standard pipes as the walls are thinner so they can carry more fumes and possibly oil / oil droplets" But surely the hosepipe is connected onto the original connectors at both ends, that will be the limiting factor so flow will be the same, no?

David Smith

"I've been giving some thought to all the 'factors', and I've come to the conclusion, that the 'multiple factors' theory doesn't explain it. Simply because for any of the known factors you care to mention, you can find an engine with them, that still doesn't suck oil." Lawrence, in that case you misunderstand the theory, or at least my hypothesis. Say for sake of argument that there are 50 factors that contribute in some way to the situation that may or may not suck oil. Each will have degree of variation across all engines in use, both those that suck oil and those that don't. - Think in terms of statistical Normal Distribution curves. For example a factory-drilled oil gallery will have a nominal size but there will still be variation between one engine and another, in the diameter and surface finish that will impact on the rate that oil flows through it. Take those sorts of variations across all 50 factors and in most cases they will cancel out. This will produce a "normal" condition for the A-series intended design that doesn't suck oil. But in a proportion of engines the net effect of those variations will result in an engine that does suck oil. Some of the factors will be common, relatively easy to identify, and may be the most significant: viz. temperature, oil level, viscosity. But they won't be the whole story for every engine. Others will be much less obvious and will vary between one engine and another with the resultant symptom being the only common feature.

Guy W

Dave Squire. Wrong engine I'm afraid. None of this really applies to your engine, which is a 1500 Triumph engine, not a 1275 A series. Guy. OK. Yes, I did think you meant owner induced variable factors, rather than factory variables. So what you say makes sense, assuming that the tolerances accepted by the factory for all the variables were sufficiently slack enough. But is that REALLY likely? Could engine blocks be so different? Oil gallery holes so different in size? How about the suction provided by the SUs? It's greatly reduced from manifold vacuum, so manifold vacuum variation can be excluded. Is it likely that HS2s were so varied in tolerance that 2 different pairs would produce a different level of suck? And anyway, a reduced level of suck from an HIF, STILL results in oil suck. The oil filler caps. They might well vary in flow rate, but I've shown that it makes no real difference to my Sprite engine or my Midget engine. (Accepted that seems to be the only explanation for Bob's cure). Going back to the oil flow, surely BMC were able to make blocks and components to sufficiently close tolerance, that the oil delivery to the mains/ends/camshaft journals, and of course the timing chain would be to all measurable purposes, the same on all the 1275 engines they produced to a particular spec? Here's a thought. Could there be a series/batch of 1275 blocks, that are measurably different to earlier or later ones? And it is those blocks, that suck oil? But again. We have to go back to the beginning. When they left the factory, they didn't suck oil. Had they done so, it would have been noticed in the first winter, and there would some common knowledge of this problem in the collective memories of the motor trade, -- at least in the mechanics. And yet I've NEVER met a single mechanic who'd EVER heard of it, and they didn't know about it in BMC oxford technical in the 1980's. This is why I can't get past my gut feeling, that this fault has been introduced to the engines at rebuild time, and my money's still concentrating on the front end of the camshaft.

Lawrence Slater

Lawerance, These engines were machined by man with micrometers in there pockets, No computers involved. Were there differances...id say there were more variations then from engine to engine then there was exact duplicity of engines...the manufacturing standards I doubt were as exact as the US mint When I rebuilt my engine I had my new crankshaft indexed, it took 20 thosands on the mains and 10 thosands on the big ends in order for the piston tops to all hit at the exact same height. That was just manufacturing at the time, there was a range of factory slop But I still go back to there is nothing wrong with the engine...most people warm there engines up before driving Prop

Prop and the Blackhole Midget

I wasn't limiting variation in engines just to factory work. There is no reason to. I was including all variable factors and part of the cumulative mix. And none of the variations need to be great if you are prepared to accept that there is likely to be a cumulative effect. In some cases these will cancel each other out, whilst in other rarer occasions they may total up until the symptom occurs. But don't misunderstand. I am not suggesting you are wasting your time with investigating your own engines. And in letting others know your findings. Just don't put too much score in necessarily ruling things out based on other's experience.

Guy W

"Just don't put too much score in necessarily ruling things out based on other's experience. " I'm not Guy. It's exactly because of other people's experience, other people saying that their engines behave in just the same way mine does re oil sucking, and that they do so, with standard and modified engines, with and without an HIF, or pancakes/K&Ns, etc, that I think that all those myriad variable factors are not the cause. I feel that for oil sucking to take place, there has to be an overriding factor, an anomaly, that without it's presence, oil sucking can't happen.

Lawrence Slater

Back to my Midget then. Bob runs without a thermostat. The other day I put an 88c 'stat in, and it still sucked oil at the same place, and the same temperature reading. So today, I decided to go to the other extreme, and copy Bob. No 'stat. And? It still sucked oil. It sucked oil at the same place, about 2.3 miles out. But. The temperature of the water when it started sucking oil, was barely 110f. In fact even after 30 mins driving, the temp' was still only 120f max. So it would appear that the temperature of the water, has little to no effect on the engine sucking oil. It's the temperature of the oil that matters, in as much as the water can be cold, but the oil can still warm enough to thin sufficiently, to stop the oil sucking effect. So now to my SPRITE engine.

Lawrence Slater

Front off to give full access. I'll mount the radiator on the valance(I've got an electric fan installed in that) and use extended hoses to connect it. Then I can still run the engine for extended periods. Loosen engine mounts, jack up engine, reverse gear h/brake on, socket on bar with extension, 'gentle' tap with toffee hammer to shock the nut loose, jack up engine a bit more, off with the pulley and timing cover, and VOILA. :).

Lawrence Slater

In February 2012, I stripped my spare engine and posted the results here. I wrote ----- "The end plate is badly worn and end float is at least 0.013 inch ----- " The book quotes MAXIMUM endfloat should be 0.007 inch! Excess endfloat will allow the camshaft to recess too far away from the camshaft retaining plate. Intead of the oil only being delivered through the oil feed hole once per revolution, it will leak out into the timing chain cover constantly. The oil pressure will force it out. As you can see from my picture, the endfloat on the engine in my Sprite, is 0.010 inch. Actually I can just squeeze a 12thou blade in there, but I'll call it 10. So I have 2 engines with too much endfloat. I thought it was significant on my spare engine, I think this is even more significanct, since BOTH engines suck oil. Before I pull the sprockets to inspect the camshaft endplate, I'm going to modify my spare timing chain cover, in order to observe the oil as it 'fills' the cover, --- if it does.

Lawrence Slater

Indeed yes Dave. Thanks.

Dave Squire

Again going back to my spare engine, that I stripped back in 2012. I posted this picture. It shows light bleeding between the camshaft retaining plate, and the engine front plate. Hence oil can seep through to the cover constantly, and not only once per revolution of the camshaft. I measured a 4-5 thou gap. Picture of the gap under the camshaft retaining plate from the engine in my sprite, to follow next.

Lawrence Slater

Here's a picture from the oil sucking engine currently in my Sprite. I measured the gap between the camshaft retaining plate and the engine plate, as 6 thou inch. As with the spare engine, oil can easily flow under this gap, esp' as it's under pressure. Again, the oil flows constantly, and not only once per revolution of the camshaft. TWO smoking guns, from TWO oil sucking engines. This must be more than a coincidence.

Lawrence Slater

Here's my remote radiator setup. Tommorow I'll put a window or sight tube in my sacrificial timing chain cover, and start it up for a look inside at what the oil's doing - (hopefully).

Lawrence Slater

I decided to fit a window 'and' a sight tube, as I don't know if either or both will be effective in showing the level of oil in the cover. The next step is to cut a hole in the cover, and fit a clear length of tube to the brass elbow. But I might get a slightly thicker bit of clear plastic for the window, --- just in case. :)

Lawrence Slater

Seems a shame to cut a hole in this. But I can easily plate it afterwards. I want to see if the long tube will stop the sucking on the Midget, even if I am able to pinpoint the cause.

Lawrence Slater

Lawrence, seriously impressed with the commitment to the cause :) It'll be a right bugger if the extra volume of the sight tube tips it over the edge to not sucking! What size you planning (too small and it won't register correctly, too big and it will impact the time to sucking, if ever)? I'm thinking 8mm as a possible without doing a load of calcs. best of... MGmike

M McAndrew

Wow..... Isnt this how Victor Frankenstien got his start?

Steven Devine

I'm new to this bulletin board but thought I'd add my experiences. Bought a nice midget as a daily driver while working on my tr3. It's been pretty reliable except after changing oil and filter and topping dashpots it began burning plumes of oil. Disconnected the y piece allowing the timing chain to vent to atmosphere and blocked the two brass tubes on the carbs. Enlarged the venting at the filler cap to prevent positive pressure. All is well now although I could believe that the slight oil leak is caused by the lack of crancase vacuum. I await your experimental results with interest Kenneth

K munnoch

You are going to need a longer fan belt.

Guy W

lol Guy. And I'll have to take the mole-grips off too. ;). Electric fan in the valance, so no plastic blade to obscure the view. Mike. You may be right about the changed volume changing the dynamics and the outcome. But I'm not going to connect the breather or sight tube to the to the carbs. So it should simply be a way to see what level the oil reaches inside the cover. If anything, the volume in the cover is reduced. The brass elbow and intended size of the sight tube is small in capacity, compared to the much larger chamber of the standard breather (oil air separator) canister. I'm not expecting the oil to fill the entire cover. But so far, my logic says it will at least reach the take off tube on the right of the modified timing chain cover. The bottom of the entry hole to that (baffled), is pretty much in line with the standard entry hole. See pic. I may not solve the mystery, but I'll go down fighting. LOL. Kennith. Welcome, lol. "--- except after changing oil and filter and topping dashpots it began burning plumes of oil --- " Could you elaborate? When did you change the oil, summer, autumn, winter? Was it particularly cold on that day? What oil did you put in the dashpots?

Lawrence Slater

Steven, I'm starring in my own home made movie. Call me Karloff, Mkii. lol.

Lawrence Slater

Hi Laurence Changed the oil in October. Weather relatively mild. Added a bit of 20/50 to the dashpots. I should add that the midget has a healthy oil pressure- 80 psi at 2500 dropping to 40 at idle. The vacuum from the twin su carbs didn't seem that high so the volume of oil sucked into the carbs was a real surprise. That brought me to the forum and the realisation that I was not alone! Kenneth

K munnoch

This thread is getting like an epic novel you cant wait for the next chapter and people are realising. We are not alone!

mark 1500 on the road Preston Lancs

Kenneth Is it only doing it for a short period, or is it constant?

Dave O'Neill 2

It seemed that the oil suction happened under load and at idle. My guess is that the timing chain cover fills with oil , or perhaps partially fills then is flung by the timing chain into the breather pipe where the vacuum sucks the oil- as much as a litre on a short 15 minute drive. Note that without the vacuum I've never seen liquid oil leave the breather pipe- only a very small amount of vapour with a fine mist of oil as you would expect. I suppose there may be two factors- the vacuum from the carbs and the positive pressure in the crankcase- a push-pull effect- but there must be a substantial accumulation of oil in that timing chain cover. I am happy to run the car with the non standard set up that I have but it is an interesting issue. Looking forward to the test results from Lawrence's "timing chain cam"

K munnoch

October? Fife?. My limited knowledge of anywhere north of Watford, informs me that this is somewhere north of the border, and closer to the North Pole than I am. Hence probably quite chilly in October. ;). Oil change in cold ambient temperature seems to tally with the first post in this thread. underlying problem, just waiting for fresh oil in cold weather to expose it. " --- as much as a litre on a short 15 minute drive." "My guess is that the timing chain cover fills with oil , or perhaps partially fills " Yep, yep. Those are the only logical conclusions for that amount of oil. Not flung into the breather though. Once the cover is near full of oil, it's sucked in, no doubt as you say, aided by the push from the sump pressure -- which on it's own, as you've also found, isn't enough to push the oil out. The main point is though, that there just doesn't need to be that amount of oil in the timing chain cover, and there shouldn't be. So how is so much getting in there? Tommorow I'll complete my window, and with a bit of luck, I'll actually be able to prove the level of oil in the cover. Then: 1). I'll pull off the cam sprocket and have a close look at the camshaft retaining plate. 2). Seal it to the face of the engine plate so no oil can escape out of the sides. 3). Find a way to reduce the endfloat to circa 3 thou inch, and partially obscure the oil delivery hole with solder. 4). Check the level of the oil again in the garage via the window (if it workled in the first place that is). 5). Refit the real cover, assemble the front end, and go for a drive.

Lawrence Slater

"Once the cover is near full of oil, it's sucked in" What is interesting is that once the breather pipe entrance is filled with oil such that no air can be drawn in, then even a very low vacuum (suction) from the carbs, will lift a lot of oil, a long way! The calculation gives a vertical lift of around 30 inches. of oil for just 1 psi of suction. With this, the actual amount of suction under those conditions, is almost irrelevant, so long as the other conditions are met.

Guy W

I agree Guy. Which as we said before, explains why the HIF breather port, which measured at a slightly lower vacuum than the twin SU's breather ports, still managed to suck oil. You could imagine the cover being partially full of oil. Not enough crankcase pressure to push it up the canister, and whilst the drain holes are still trying to catch up, the oil sits balanced. Then add a slight suction, the balance tips, and up the oil goes. The cover empties, and starts to fill again, but as the oil is getting warmer, it drains faster, the level of oil in the breather cover doesn't get so high, and the suction sucks on vapour instead of liquid oil. Here's another off the wall thought though. I've wondered about this before, so I have to experiment to elliminate it. A sudden increase in suction? Open the throttle, more air enters the throat of the SU. The piston rises, and this keeps the depression near constant. But what if when the throttle opens, the pistons were sticking? The manifold would still demand more air. Where would it suck from? The breather pipe. Why might the pistons start to stick? If they iced up. So tomorrow I'm going to direct hot air from the exhaust into the pancake tubes on the Midget. Then I can stop thinking about that possibility too.

Lawrence Slater

would it be possible to have a small tube from inside the canister to the top of the cover all internal so when the canister is partly full the carbs will not have a full vacuume to suck the oil.only guessing not familier with the a series engine.

mark 1500 on the road Preston Lancs

Lawrence, Is the suction at the carb end, where the pipe enters the carb throat, caused by low pressure in the carb, or by a venturi effect of the intake charge rushing fast and steadily across the end of the pipe? I had assumed the latter, which would give more suction on the breather at higher, constant revs = exactly what is wanted. If it is based on lowered throttle body pressure, then that will be at the moment you "snap" the throttle open, the butterfly flips open but the carb piston hasn't reacted. This would be at lowered revs, and not so useful. In reality. it must be a bit of both. This leads to another thought - have you, in you enquiries, discovered what sort of air filters are in use on the various sucking engines? I wonder if more restrictive filters such as the commonly used pancake designs, result in stronger suction on the breather pipe. But then again, if 1 psi will lift a 30" column of oil, then pretty well any level of suction has the potential to result in an oil cloud, if the other conditions are simultaneously met.

Guy W

Guy. I'm still thinking about your first paragraph. But I think the depression in the carb is caused by the descending piston in the engine block, which causes the vacuum at the inlet manifold, which is transferred to the carb body when the butterfly is opened. It's the rising piston in the SU that prevents the depression approaching the level of the inlet manifold. This from http://sucarb.co.uk/technical-carburetters-introduction -- "Opening the throttle disc (4) allows the manifold depression to be communicated to the body of the carburetter and also to the chamber above the suction disc. The piston will rise, allowing a mixture of air and fuel to pass underneath it to relieve the depression. The piston will continue to rise until the depression has reached a value which is just sufficient to balance the weight of the piston, together with the load exerted by the piston spring. It will be appreciated that approximately the same depression can be obtained whatever the demand and that the piston height will be governed by the mass of mixture flowing beneath it. " On your 2nd para, my Sprite has K&Ns with stubstacks, and my Midget has original paper filters in the original saucepan containers. I think I've cause confusion by mixing up the terms in a previous post. Both suck oil.

Lawrence Slater

"would it be possible to have a small tube from inside the canister to the top of the cover" I don't think there is enough clearance between the cover and the cam sprocket.

Dave O'Neill 2

Nope there isn't. It's at most, about 5mm from the timing chain face, to the inside of the cover.

Lawrence Slater

Congrats... 200 postings and counting, I no doulbt this thread will achive 500 or more I say we go over everything one more time maybe we missed something ®¿~ Prop

Prop and the Blackhole Midget

would one on the outside work

mark 1500 on the road Preston Lancs

I'm trying for 1000 this time Prop. :). Mark. In essence, all you are doing is removing PCV, and leaving the breather system open. So yes it will stop the oil sucking, but it would also defeat the PCV system, unless the vacuum was increased, and than you'd be back to where you started. There are two solutions. One is to provide a 2nd suction point, and the one proven to work, is from the petrol pump blank on the side of the block. The other and my favoured solution at present, is to identify the anomaly and rectify it. I'll adopt the former, if I can't do the latter.

Lawrence Slater

Drill the chaincase drain holes to a slightly larger size?

Guy W

We talked about that before Guy. I asked if anyone thought that the main cap would be weakened by doing so. Looking at the cap, I wouldn't want to risk it. But I agree, if the holes were larger, there wouldn't be a problem.

Lawrence Slater

Version 34.0.5 This'll confuse the hell out of somebody someday. But the FireFox picture will make perfect sense. LOL.

Lawrence Slater

Well I did the deed today, but I'm not entirely sure that it was cold enough in my garage to cause the sucking conditions in the timing chain cover. It felt positively balmy in fact, even with the doors open at both ends. Anyway, here's how it started off. Easy to see inside. Just to the left of the jubilee clip, you can see the centre of the end of the camshaft. And below the brass elbow, the rim of the camshaft sprocket, just inside the teeth. Next a still from a video with the engine running.

Lawrence Slater

Here's the still from a video with the engine running. The jubilee clip is just visible at the bottom of the frame. The engine was actually pretty warm by this stage. When I first started it, for about 45 seconds, the window was clear. But then within a few seconds after that, it was suddenly obscured by oil. At first, you could see a swirl of oil at the bottom of the clear window, as it covered the camshaft rim, visible in the previous post. Then, a curtain of oil descended from the top down and completely covered the inside of the window. I wasn't able to capture that on video yet, and a still I took just looks black. But my naked eyes could see what looked like waves of oil being swirled around. And keep in mind, that the plastic window, is at around the height of the entrance hole to the breather canister. Anyway, here's a still of the base of the sight tube. It shows oil in the tube, being 'bubbled' up the tube, for want of a better description. I'll upload the video in a mo'.

Lawrence Slater

Here's the link to the video of oil in the sight tube. (reference the still in the previous post). http://tinyurl.com/omwcod7 I use Chrome to watch the video btw. For some reason, FF and IE, won't let me view it. I shot this with my camera rotated 90 degrees clockwise(or was it ccw?), and don't know how to correct it. So anyway, tilt yer 'eads ;). Brass elbow and jubilee clip (bottom) on left of screen. That's plenty of oil, if sucked up to the carbs, to make a luverly smoke screen. I also pumped the throttle, and doing so made the column of oil rise and fall nicely. But as said earlier, the engine was already pretty hot by this stage, so not as much as would have been the case, if I were able to time it right and get it at just the right temperature. These are static conditions in my garage, on a 'warmish' day. Also, the faster the revs, the faster the oil delivery to the timing chain cover, because the camshaft delivery groove will meet the oil hole in the camshaft retaining plate, more frequently. I'll try again tomorrow, to get a clearer shot of oil filling the cover, -- if it will completely. But I'm reasonably satisfied, that there is too much oil in the cover, and the next step is to confirm my thoughts on why that is.

Lawrence Slater

A smoking gun Lawrence! (Sorry about the pun) I'm probably jumping the gun a bit but it's good to have conclusive proof that you've got high levels of oil in the timing chain case and not some mysterious condensing oil ether that a few people believed. As a newcomer to the 1275 engine can I ask how oil is supposed to drain back to the sump? Where does most of the oil in the timing chain case come from? How could the drain be improved and would dropping the oli pressure from the 80 psi that I've got reduce the timing chain case oil level? Thanks Kenneth And just a thought I've got an Ivor sealy engine in my midget- maybe the rebuild tolerances are different from factory settings? Surely that would be too simple a reason for the oil suction?

K munnoch

Kenneth The oil comes from the front camshaft bearing. It drains through two holes in the main bearing cap. I found a couple of photos on t'net to illustrate. You can see one of the holes here, the other is obscured by the crankshaft nose.

Dave O'Neill 2

The holes are angled downwards and come out on the other side of the cap... The sharp-eyed among you will have noticed that this is a Mini engine.

Dave O'Neill 2

Liking your experiment - excellent work Watson ! If as it appears the oil is filling up the t/c case too fast for the drain, what would be the effect if a further drain was provided from the t/case front - there is just about sufficient space to braze in another tube beside the cannister spigot into the case. A pipe would then need to turn 90deg and run back between the engine mount and shock absorber and discharge into the flanged area on the block originally for the petrol pump - via another drilling. Later engines already have a blanking plate so a bit easier. This would assist in restricting oil to the level of the breather cannister base - any negatives ? Looks possible and suitable for a further experiment ? R.

richard boobier

This thread is starting to take shape, I like the work your doing lawerance Im surprised by the amount of oil and the level of oil in the T/C/C Thats got to be at least 1/2 qt of oil in the T/C/C Prop

Prop and the Blackhole Midget

Prop. The timing chain cover, canister, and breather tube can hold appx 1/2 pint IMPERIAL. If you mean a Qtr of a US Gall, then it's not that much. But 1/2 UK pint is plenty too much, I'm sure of that. Richard/Keith. The plan is to reduce the amount of oil in the cover in the first place, rather than find a work around. As Dave's pictures show, the two drain holes are quite small, but it has to be remembered that they are big enough in most 1275 engines, -- since most 1275 engines, DON'T suck oil. --- Or maybe they do, but as Prop seems to have discovered, it needs the right circumstances to occur. Whatever the situation is, for those that do suck, can the drainage be increased? I don't think enlarging the holes in the main cap is a starter. It may weaken it. I don't know if there is scope to drill additional holes in the block face, I'm going to look at it. Tom and some others, have added a 2nd connection, via the petrol pump blank on the side of the block, into a T piece that connects to the main breather tube. That reduces the level of direct 'suck' on the timing chain cover, whilst also drawing the pressure from the sump. By all accounts, this works. And it's also my preferred option if I can't find/rectify the cause. What Richard has proposed is interesting. A drain from the timing chain cover, directly back to the sump, via the petrol pump blank. Hmmm. Might work. But what might be even better, is to drop a 1/2" tube directly out of the bottom of the breather canister, and connect 'THAT' to the side of the block, via the petrol pump blank. It seems to me, that if that was done, oil entering the bottom of the canister would fall back to the sump, whilst there would also be the possibility for reduced suck directly on the cover, meanwhile vapours and gasses would continue to be sucked up the canister and into the inlet tract. This may not be any better though, than what Tom and others have already done, and it requires extra work to boot. So maybe, maybe not. BUT, here's ANOTHER angle. Fergus put up pictures of LATER covers (A+ engine?) that show a 'baffle' ring, around the internal entrance hole to the breather canister. In my description, I referred to a curtain of oil "DESCENDING" down the internal face of the cover. As there is nothing to prevent it, it falls oave the entry hole. But if that circular baffle was there, that couldn't happen, it would be diverted AROUND the hole. Perhaps, as Fergus proposed, that's EXACTLY what BMC/BL discovered was neccessary?

Lawrence Slater

There is a circular baffle fitted round the hole on A+ engines covers. I had to grind it away to fit duplex gears though so hope that's not going to cause any problems?

R Mcknight

Lawrence, thanks for running this experiment and it is certainly an eye opener. It made me think why by just changing the pipe the carbs and Filler cap, I 'cured' my oil sucking problem. The new pipe is certainly slightly smaller in diameter than the original which had 'bloated' and potentially allowed more oil to enter. the second point was that the new pipe was slightly longer so the vertical lift was a few cms more, perhaps just enough to overcome the vacuum. The third point related to the cam plate. I recently replaced the cam and as part of the refurb checked the end float which with the old cam was just within tolerance by a thou. The new cam was better and the tolerance was in by 4 thou so I didn't replace the cam plate. Does this mean less oil is delivered to the timing cover? I also run an oil pressure which does not exceed 70PSI. All minor points in themselves but it may be just enough to stop the sucking.

Bob Beaumont

Lawrence, As I don't know what oil level is required in the t/c case I suggested taking the overflow off at a similar level to the breather - certain then only acts in extremes - not all the time - so stays more as original intent. Agree pipe to sump would be a simpler alternative. Keep up the good work - many parts of the world are watching your every move ! R.

richard boobier

I'd like to start the petition :- Lawrence Slater MBE for services to ensure oil circulation inside a BMC A series engine bloody well remains there. I also think Lawrence is well on his way to proving that high oil pressure, bent camshaft plate and large camshaft end float is a bad idea.

Malc Gilliver

I'm still of the opinion that the wide duplex set up exacerbates the problem by throwing up a large continuous curtain of oil which falls past the entry to the chimney and is consequently push/pulled into the inlet. In that respect I'm not really sure that the timing cover does actually 'fill up'. Rather it acts like an old Mississippi paddle steamer in throwing what oil there is in the cover past that window. What you might do is run the engine until the level is well up the tube and visible and immediately cut it.If I'm right the oil will fall from the tube in an instant.If you're right the oil will presumably drain away quite slowly. As you say I think the A Plus set up with a single chain (reduced paddle boat effect) together and a closer fitting internal baffle ring were both measures BL felt were necessary - but in spite of this heavy investment the inline Ital engine only lasted another 4 years.

Fergus Pollock

R Mcknight. I was about to say that the A+ has a different chain setup, and that's why you had to grind off the circular baffle. Bob. I'm coming to the rocker cover cap now. Today's experiments show the very visible effect of large hole vs small hole in the cap, and quite possibly too, the effect of a wider vs narrow breather tube too. Richard. Not a pipe direct to the sump. A pipe directly from the bottom of the breather canister (which is on the outside of the timing cover), connected to the side of the engine block, via a drilling in the redundant petrol pump blanked off space. Malc. Could I have a knighthood or a Lordship instead? lol. Fergus. The chain can't throw up what isn't there. There has to be too much oil in the timing chain cover in the 1st instance, for the problem to occur. Again, not ALL SPRIDGET 1275 engines, even though they ALL have duplex timing chains, suck oil up.

Lawrence Slater

The other day, I wondered if the pistons in the SU's might be 'freezing' in the chambers temporarily, just as webbers and the like can sometimes freeze, due to the cold air rushing through them. Would this then cause a sudden increase in suction, and hence oil sucking, until the carbs were warm enough? The solution of old, was to alter the direction of the air filter inlets, towards the exhaust manifold. So today, I effectively did the same thing to my saucepans, using a bit of plastic pipe on one, and a bit of large bore heater hose on the other. The question is did it prevent or reduce the oil sucking? The answer is --- NO!!!. It had no effect on the oil sucking. So that elliminates another potential cause. HOWEVER. I DID notice a distinctive improvement in performance. A more instantly responsive throttle, and better acceleration. Did the greater length of the air filter inlet tubes cause a 'ram air' effect or something? Anybody?

Lawrence Slater

PS. Of course I also noticed that I could pretty well close the choke straight away too.

Lawrence Slater

That might imply you are running very rich - so the pipes are restricting airflow ?

Malc Gilliver

Surely the opposite Malc? If I were rich, then I would be able to shut the choke early anyway. If anything it would imply I'm running weak for winter temperature, and the warm airflow from the hot exhaust compensates for that.

Lawrence Slater

SO. --- Let me say this before reporting today's findings. YOU CAN'T -- 'YET' -- "READ THIS STUFF IN BOOKS". lol. :). If one day you can, then, REMEMBER, YOU READ IT HERE FIRST. :). And, if you’re the author of such a book, perhaps you'll include as a footnote or reference, this bbs, and this poor poster. ;). ------------------------ I declare the 1st 'discovery' stage of my experiments, at an end!. I am now satisfied that the theory I came up with, in the 1980's, is essentially correct. If you have an oil sucking problem via the PCV system -- like my THREE engines do, -- then this is the explanation that will tell you why. : ----- 1) Too much oil enters the timing chain cover!. Probably (to be finally confirmed) caused by a fault in the camshaft retaining plate, and also the mating of it, to the front engine plate. 2) When it's too cold, the oil doesn't drain back to the sump fast enough! 3) Crankcase pressure alone, is NOT sufficient to cause the oil to reach the inlet tract, or to even leave the timing cover via the breather canister! 4) If the PCV system is connected and working properly, liquid oil, ALONG WITH, vapour and combustion gasses, is drawn into the breather canister and external breather tube. At the right 'cool' temperature, it can't drain back fast enough, and is sucked all the way up the breather tube, into the inlet tract, and a dense oil cloud is emitted from the exhaust pipe. 5) Once the engine oil is warm enough, from a cold days start, the drain holes in the front main cap are able to cope with the oil fill rate, and the oil falls back from the breather canister to a lower level, such that vapour and gasses, are all that's drawn into the inlet. But because the fill rate doesn't slow down, the timing chain cover still retains a larger amount of oil inside than it needs to lubricate the timing chain. (Does this rob the engine of HP to any extent?) 6) If when starting the engine on a warmer day from cold, the ambient temperature, and hence the oil temperature is warm enough, the oil will be thin enough for the oil to drain fast enough, and oil sucking won't commence. 7) Although crankcase pressure alone is insufficient to push the oil up and out of the breather canister, the rate of air flow through the engine via the PCV system, DOES affect how high the oil travels in the PCV system. WITH THE PCV SYSTEM CONNECTED, --- 7a. Blocking off air supply to the rocker cover oil filler hole completely, causes the liquid oil in the breather tube to fall back completely. --- 7b. Leaving the rocker cover oil filler hole completely OPEN, causes the liquid oil in the breather tube to rise up the breather tube quite quickly, and the faster the engine rev's, the faster it rises. Pumping the throttle, causes an almost instant rise in the oil in the breather tube: -- EVEN WHEN THE ENGINE IS FULLY WARM. 8) The solution is to reduce the rate at which oil enters the timing chain cover! Next up, today's findings in text, stills, and full colour moving pictures. :).

Lawrence Slater

Bear with me while I try to upload a video. I've got to compress it first, as it's too big for photobucket.

Lawrence Slater

would oil presure also drop as the oil warm thus not forcing as much past the camshaft retaining plate, just a thought

mark 1500 on the road Preston Lancs

Maybe Mark. Though I have no way of measuring the flow rate to find out. As the oil thins, so does the oil pressure, but so does the flow rate into the cover, for less psi. So who knows? Anyway. First up, points 7a, 7b, from the previous list. A SMALLER hole in the oil filler cap, results in LESS oil sucked up, BUT if there's too much oil, it won't on it's own prevent oil sucking right through to the inlet. Bob, your comments confirm that. Cleary to some degree, you have exactly the same problem I have. But I think it's reasonable to assume from what you say, that there is less oil -- even if it's still more than required to lubricate the chain --, sloshing around in your cover, than there is in mine. Hence reducing the volume in the tube, and the airflow through it, stopped your engine sucking oil. Contrast that with mine, when even blocking the oil filler entry hole completely -- as I did -- , still doesn't prevent oil sucking, because air still enters the system from other places, and there is more oil in my timing chain cover. In this video clip, I was fitting and removing the correct small holed oil filler cap. Oil goes up when the cap is removed, and descends again when I put it back on. Here's a still, and also the link. Again, I view it with Chrome. http://tinyurl.com/m78os94 PS. Turn the volume up, it's in stero surround sound. lol.

Lawrence Slater

"Surely the opposite Malc? If I were rich, then I would be able to shut the choke early anyway. If anything it would imply I'm running weak for winter temperature, and the warm airflow from the hot exhaust compensates for that." My lack of clarity - I was getting at the fact that by adding the pipes you have reduced the airflow into the carb from your original condition

Malc Gilliver

This next one says it all. This is an engine start from more or less cold. The weather was colder today too, so that helped. The camshaft centre can be seen spinning just above and to the left of the brass elbow. The rim of the camshaft sprocket, just to the inside of the teeth, can be seen spinning at the bottom of the window. I've taken off the front end of the video, but it still takes a while of running, before the oil curtain starts and fills the window. Watch the full clip, and you'll see the oil curtain come down, fill the window, and then I pan to the tube where you see the oil rising. I think that what happens in real life with a breather cansister fitted, is, at first the oil drains cope. Then as the oil level rises, the chain, as described by Fergus, drags the oil up to the top of the timing chain cover, and it runs down the inside face. But because the oil fill continues to outrun the oil drain, the swirled oil dragged to the top, increases, until eventually the cover is pretty much brim full. Then as the oil warms, it thins, it falls lower in the cover, there's less in the canister, and only gasses and vapour are sucked up from that point on. Now this is MY engine we are looking at here. It may well be an extreme case. But for oil sucking to occur, there has to be an element of this going on in other engines too. To a lesser or greater extent? I know not. But it's the only rational explanation. Here's a still, and here's the clip to the full length feature too. http://tinyurl.com/pewaglg It's got the great title of --- "Running from cold" LOL. :).

Lawrence Slater

Ok Lawrence, in general you have just demonstrated what you/me/others have said/believed for months that cold thick oil builds up in timing cover etc etc. What IS the breakthrough (?) is the rocker cap issue! To suck oil out, somewhere in the system an equivalent volume of gas must be entering. This must come from either blow by from the pistons, thro the hole in the rocker cover cap or through crankshaft seals! Since our aim is to stop leaks at the crankshaft seals, blocking the rocker cover "leak" will be compensated in part by more air coming in from the crankshaft seals, reducing the chances of leaks? THe other bit I'm not sure about- do the bypass gasses and the seal air leaks come up through the sump and into the timing cover by way of the oil drain holes? If gas is coming one way, won't the flow of oil back into the sump through the same holes be hindered? Leading to higher levels in the cover?

Graeme Williams

Lawrence my memory is failing me. Is there a hole in the front-plate which corresponds with this hole in the block? And, if so, how does the position compare with the opening into the canister?

Dave O'Neill 2

No that's not it Graeme. The breakthrough if it is one -- (since I've believed it since the arly 1980s) -- , is proving that the oil enters the timing chain cover, in EXCESS amounts. The rocker cover oil filler cap, is an incidental in terms of it's effects, if there is too much oil in the TCC. Just fixing what you call a "leak" in the cap, doesn't solve the core problem, and in my engine"S", doesn't prevent oil sucking either. The aim isn't to stop leaks at the crankshaft seals, it's to stop oil sucking. Rear scroll leaks are prevented by having a properly working PCV system connected. All that's required now, is to reduce the level of oil in the TCC, by reducing the rate at which the oil is fed into it, from the front camshaft journal, via the camshaft retaining plate. That, is the next stage of discovery. The stage after that, will be the remedy.

Lawrence Slater

There is indeed Dave. Scroll down to my post, 18 September 2014 at 18:57:36 UK time. All you need to know, with a poor sketch from me as well.

Lawrence Slater

Yes, indeed. I would think that the purpose of that hole would be more to do with crankcase breathing than oil overflow, although that wouldn't be the case if it is present on the small-bore engines. Given the size of the hole, you wouldn't really expect the oil level to reach the top of the breather hole, thereby creating a seal and 'sucking' to commence...or would you?

Dave O'Neill 2

Yup. The first thoughts were overflow, but the prime purpose must be pressure transfer. However, you would think that the oil would 'overflow' through there too. Now though, seeing the oil run down from the top, down the inner face of the timing cover, I can understand why the oil doesn't overflow back through that hole, and prevent the oil entering the breather canister. But anyway, because of the relative heights in the cover, by the time the oil is at the level of the hole in the block face, it's 'already' flowing into the breather canister anyway.

Lawrence Slater

So how about ADDITIONAL drainage? Here's a picture of my spare engine block. The only potential site for another drain hole is here I reckon. It's the only place low enough and also inside the timing chain cover. But would it suffice, and would it weaken the block if it was big enough to do the job? The other unknown, is what might happen if the oil drained out too fast? Would the chain and sprockets run too 'dry'? Before considering that, as a last resort, I'll concentrate on reducing the oil fill rate into the timing chain cover first. I'll do that by making sure I have a properly fitted, flat, and correctly endfloat sized, camshaft retaining plate. PS. The two black // lines on the left of the face of the block, are the height and width of the internal breather canister entrance hole. As you see, the so called 'overflow', hole is bang in the middle

Lawrence Slater

And finally for tonight, here's a picture of the camshaft sprocket. It's a bit like a saucer. Because the chain when it's on the teeth, runs so close to the inner face of the timing cover, and the oil is also falling down that face, I'm pretty certain that the sprocket does a good job of holding the oil there, as if in suspension. It doesn't get an easy chance to flow through those 2 holes in the sprocket, to reach the potential 'overflow hole behind it. It can more easily flow and be sucked, right into the breather canister in front of it, only to be replenished by the surge upwards from the chain, and the constant overfill of oil from the camshaft journal.

Lawrence Slater

how about just using a fully synthetic 20/50 (or wider range) oil, better protection over its life AND runny enough even when cold to drain away at sufficient rate to avoid the issue?

David Smith

Lawrence With reference to the sprocket, I also replaced the sprocket with an adjustable one which has lots of holes in it. Another factor reducing the possibility of sucking in my engine now.

Bob Beaumont

Hi David. In the early 80's, I started using Mobil 1. Not as an attempt to cure the oil sucking, but just because I read about how it was the best thing for engines, since sex was invented for humans lol. It didn't prevent the oil sucking though. I used to use it in my T140D boneville too. I only really stopped using it, becuase at the price, I began to question it's superiority, and went back to GTX, which I got VERY cheaply, from the BP staff shop in the BP office I worked at. Also, and I know I keep repeating it, but not all 1275 Spridget engines suck oil. Most don't. But most people use the same standard 20:50 oil as is used in the oil sucking engines. Bob. Yep, that's interesting. My teeth are a bit knackered, and I also suspect the nose is worn and contributing to the excess endfloat. (It's the original in the engine as far as I know). So I'll get a replacement with extra holes too. Whatever factors may exacerbate it, oil sucking is due to a fundamental fault, and unless it's present, all the other contributory factors won't start the oil sucking. That fault is the overfilling with oil, of the TCC. -- Unless either I, or someone else identifies something else, with the supporting evidence to prove it. :).

Lawrence Slater

I agree Lawrence not all engines will or ever do it . When I turbocharged my 1275 using MG Metro parts I could not use the correct parts for the turbo drain as it returns via the mechanical fuel pump boss on the block. As it was undrilled on the Midget Block I added a drain via the backplate into the back of the TCC. Even more oil into the TCC and that engine even with increased crankcase pressure and extra oil being fed into the TCC never sucked oil. The only thing it sucked was my pockets dry!

R Mcknight

R Mcknight. I don't suppose you happen to have a pic or two of the engine bay on that car do you? Hi Malc. I missed a reply to what you said you earlier. --- "My lack of clarity - I was getting at the fact that by adding the pipes you have reduced the airflow into the carb from your original condition -- " I get what you mean now. The longer, slightly narrower pipes I added, would have had the effect of enriching the mixture, due to reduce airflow. OK. But overall then, the complete mixture to the inlet manifold would decrease, and I would have expected a reduced throttle response and performance. However, what I noted was an increase in performance, and better response. Hence I wondered if it was an increase in the velocity of the mixture causing that improvement. See -- "Posted 13 January 2015 at 18:49:42 UK time" lower in this thread, if anybody else fancies answering me. :).

Lawrence Slater

Lawrence, From the extensive work you have done, I take this view. The oil is draining down the inside of the cover, not the same as too much oil. I wonder if the fact you have large camshaft endfloat and high initial oil pressure is the issue. If you just had large end float that should reduce the oil pressure as the oil is pouring out, conversely if you just had high oil pressure because the flow was restricted by the end plate that wouldn't cause an issue. But put the two together, and it's sort of pointing to your oil supply system - either the spring is too hard, or the oil pressure release gallery to the sump is restricted, the pump is too big, or the system is not loosing enough oil through the cross drillings. In simple English, you have too much oil arriving at the camshaft end plate. Malc

Malc Gilliver

Hi Malc. All I can say, is that you haven't read the whole of this thread, or perhaps the links in it. And if you have then there's no point in my repeating everything about my oil pressure and camshaft retaining plate again. :).

Lawrence Slater

Malc, It could also be that the gallery continuing on to the rocker pedestal is restricted which would also result in higher pressure and more leakage at the cam bearing.

Guy W

Guy, That's pretty much were I am, I think it's an oil system issue. Lawrence, As you know I have the same issue as you, and I really appreciate all the work you have done, and yes I think I have read this and other threads, and yes I have watched all your lovely videos ! I think you and I have high pressure oil spraying all over the inside of our timing covers. I posted my thoughts to generate comments like Guy has made - where do I look for machining issues or assembly issues that may generate the high volume, high pressure spray from the end of the camshaft that is causing oil to reach the outlet pipe of the timing cover. I see a possible bodge in the form of a plate almost like a louvre over the air outlet. I see another bodge as a tapping of the bottom of the canister taking oil back to either the cover or even the sump. But I'd rather strip the engine and just drill out a hole or two and redirect oil to where it should be going, or maybe a second attempt at getting the OPRV out and adding a few spacers to reduce pressure a little for the winter ! Malc

Malc Gilliver

It's all been said before. How many times must the same things be discussed? The oil pressure has been discussed many times, and nothing new is said. The issue of the rocker cover feed has also been discussed at least 3 times, and nothing new is said. All of the same questions and suggestions could be repeated, and all the same answers will be repeated too. I just don't fancy doing it. When I want to review or re-read something, I look for it in the previous threads and posts. Yup, I said, I'm considering a tube out of the bottom of the breather canister, but before resorting to that, I'll do what I said I'm going to do about at my camshaft retaining plate, because that's where I reckon the fault is. Whatever the result is of that, I'll report it, as something new. :).

Lawrence Slater

Hi Malc, I should clarify what I meant by the links I referred to. I didn't mean the links to my videos. What I should have said, was the referrences to all the previous threads covering engine breather and oil sucking problems. Because if not in this thread, then pretty much everything else about oil pressure, and the relief valve, and the feed to the rockers etc, has already been discussed in those previous threads. Those threads got so long, in great part, because the same points about various things, not only oil pressure, kept on coming up and being answered, over and over and over again. The result was that some people said they couldn't open the thread, or simply couldn't be bothered to open it and read it. That's why I suggested, way back in September in this thread, that people should read the previous thread, "engine breather". I even reactivated it for ease of access. Of course, you or anybody for that matter, don't have to agree with my conclusions or answers. But for my part, I'm done discussing/repeating the same points about high oil pressure, the rocker oil feed, or vapours or anything else that has already been said. Anything new that isn't already in this or the previous threads is interesting. But old, is just making this thread grow without purpose. IMO. :).

Lawrence Slater

What would be very interesting, is for someone else to strip an oil sucking engine, and see if the same conclusions can be drawn. I've got 2 engines currently sucking oil, and one previous sucker, now in pieces. I've already identified two things from one of the current engines (in my Sprite), that are just the same as in my stripped engine. Namely a gap under the camshaft retaining plate, and excessive camshaft endfloat. It's my bet that if I pulled the cover off my Midget, the same faults will be found in that engine too. But to make it more useful still, it would be good to see someone elses engine as well. So if anybody fancies it? All you need is a couple of lengths of underground gas pipe to extend the radiator hoses, the plastic lid from a box of ferrero rocher chocolates for the window, and an elbow and length of clear pipe, for a sight tube. Plus of course a spare timing chain cover to cut a hole in.

Lawrence Slater

Here's a final video of the complete ensemble. If anyone has any suggestions, (other than "scrap it" lol), for an experiment that might be useful, I'll give it a go. Otherwise, I'm going to take off the TCC tomorrow, and take off the Sprockets to get at the camshaft retaining plate. http://tinyurl.com/mrlt4he

Lawrence Slater

I think what would be quite helpful would be if one or two of the pro engine builders were to elect to give us the benefit of their experience.Certainly it would be remarkable if they hadn't come across this problem and know the solution.

Fergus Pollock

You might try fitting a new thrust plate and sealing it with Wellseal to stop any sideways spillage, and then tune your relief valve to blow off at 70 followed by 65 then 60 PSI, to see if it reduces fill.

Fergus Pollock

Lawrence Hi I've tried to stay away from this thread but it's sucked me in lol The hotrod guys here that have breather problems with their big lumpy camshafts not producing enough vac to make their breathers work, use cheating methods to get their breathers working Some use an electric vac pump into the tappet cover to get some extra vac and others use a venturi system in the exhaust hooked to the tappet cover to create vac Just reading through your posts I feel that your problem is being caused by the breather vac supply being connected to the timing cover ONLY which is sucking/holding the oil in the timing cover The only way to fix it is neutralise the vac in the whole motor and then this will allow the oil being held in the timing cover to flow back to the pan properly There needs to be a breather connection between the timing cover and the rest of the engine either externally or by enlarging/creating a drain internally that is large enough to allow oil to flow back without being restricted by airflow from the crankcase up through the timing cover into the breather willy

William Revit

I still think neutralizing the crankcase would fix it but as you say that is a fix and not really getting to the cause of the problem -- Maybee if the drains through the maincap are clear and not blocked by a wayward piece of gasket or something and the rest of the breather system is standard there has to be another reason, IF they didn't suck oil new My thinking now is that the engine oil is too thick for the ambient temperature restricting it's flow back to the pan or there is too much suck on the breather system being caused by either restricted aircleaners compared with when new by being dirty or of inferior quality OR carburettor dashpot oil thicker than recomended for winter running or dirty/sticky dashpots causing slow dashpot movement which in turn would give more suck on the vac hose to the breather. You've probably already been through these but I can't be bothered reading ALL the posts willy If the drains through the main cap are clear,It might just be easier to run a hose from the tappet cover or side cover or that spare fuel pump plate into your existing breather below the gauze to neutralise it all and drive on I'm sure some of the Minis here had their breather coming out of one of the side plates but I might be getting mixed up with MGBs which definately did .

William Revit

Just read back there about 20 posts ago where you had the block marked out for an extra drain I reckon you're on a winner there but not because of it being an extra drain but because that will allow vent air to flow through to neutralize the pressures/vac in the block/timing cover and allow the oil to return to the pan through it's normal holes in the cap without vent air fighting against the flow of oil in these holes willy 30degC here yesterday -no oilflow problems

William Revit

Willy There's no side cover on the 1275 engine...except on the Cooper S.

Dave O'Neill 2

Dave Yeah right I'm a bit of a B series bloke really So the Midget block is solid down the side like the K series 1275 minis here---------got it--thanks No side cover breather there then. cheers willy

William Revit

I wouldn't 'fix' the problem NY lowering the by-pass oil pressure. As it only happens in cold weather and with cool oil, lowering the pressure is likely to have far more detrimental effects at 99.9% of the rest of the time when the oil is properly warmed up! But even with the correct pressure at the pump or rather at the gauge, the pressure at the front cam bearing feed could still be too high.

Guy W

Quote: William Revit, Tasmania, Australia "I reckon you're on a winner there but not because of it being an extra drain but because that will allow vent air to flow through to neutralize the pressures/vac in the block/timing cover" Willy, there is already a large hole between timing chamber and CC but it's above the breather take off level - so air flow between the chambers is already there. Jim

J Smith

The higher hole in the block face that we are talking about. I previously speculated that it was an oil overflow hole. But I think it's more than reasonable to assume, that's not it's prime purpose, even if oil can/does overflow back through it. I wrote this recently to someone. PEH = Overflow hole = pressure equalisation hole. 1). Did anyone ever consider, that the oil flowing back into the sump, would be opposed by the flow of air clearing the gasses in the opposite direction? Presumably yes. And the PEH in the block face, higher within the TCC, is much larger than those 2 oil drain holes. So as in the true nature of it's name, the pressure in the crankcase(sump) should be equal to the pressure in the TCC, and allow for the free flow of oil through those two small lower drain holes. =======. But of course, if the quantity of oil is too great, when it's too cold, it won't flow freely back into the sump at a quick enough rate. " -- fitting a new thrust plate and sealing it -- " That's exactly what's on my list of experiments Fergus. But before I remove the modified cover to do that, I'm going to connect it's modified breather canister, and see what happens.

Lawrence Slater

Fair enough Jim I'll stick to B series -- as I mentioned I let myself get sucked into this - I'll have to spend some time and read back through it all cheers willy

William Revit

Not that I want this thread to become a discussion about MGB breather problems, but you might like to read this Willy. :). MG MGB Technical - Breather fiasco!!!! http://www.mg-cars.net/mgb-technical-bbs/breather-fiasco-2009112911001820097.htm And the PDF, at the end of this link. http://tinyurl.com/pfq5ox7

Lawrence Slater

I had that problem on my MGB based kit car - the breather was completely blocked - that was easy to fix, remove breather, dump in bucket full of petrol, leave for a week, shake diluted gunk out, repeat until no gunk. BTW, you might remember when I had my timing cover off, I removed, cleaned and sealed the camshaft end float plate with blue hylomar and for a time it did stop sucking oil, but I wasn't sure if that was me driving, the weather or could have been the hylomar holding. Malc

Malc Gilliver

Lawrence, I am sure I have mentioned this before, but back in 1982 when I was building the 1275 engine for my race mini, my engine guru drilled out the two drain holes through the front main cap and rounded the edges of the holes (both ends). The drill he used was only one step up from the std size drain hole, but it was just enough "to stop the timing chain cover from filling with oil". My guru had built dozens of race engines in NZ Mini Seven racing, so knew a few tricks. I was concerned when he pulled out the drill that it would weaken the main cap, but he said he had never had a cap failure. He said more oil would accumulate in the timing cover because we were fitting a new pump and running at constant high revs. The A-Series engine timing chain needs a lot of oil to help it survive, so the level of oil in the timing cover needs to be enough to help the chain, but not enough to flood the vent canister. It's a fine line between enough oil and too much, and as you have discovered the oil temp and viscosity affects this problem, as the drain hole size is the flow control for the oil drain back into the sump/gearbox. Just my 2 cents worth. Tony Black Mountain Australia

A L SLATTERY

Lawrence Thanks for that - very interesting You know, I have never had a problem with B series breathers, probably because every time I do an engine everything goes in the tank,for a clean including side plates with their breather gauzes -- just lucky by the look of it Now back to the important stuff Tony Slattery has a good point there but if you didn't want to risk going that way your suggested hole might be the answer What oil have you got in your dashpots and do you think it might just be a case of your engine oil being a bit thick for the cold weather cheers willy

William Revit

On the Castrol website here it lists 3 different GTX oils for a Midget 15w40 = 15w50 = 20w50 I would think from that 15w40 - cold weather 20w40 - normal 20w50 - for spirited driving I stand to be corrected but that;s how I read it willy

William Revit

Hi Willy. Unless 20:50 is different today, to what it was when 1275 Spridgets engines were first employed, then oil isn't the culprit. Yes, it's the cold weather that sets it off. But NOT all 1275 Spridget engines suck oil, and most use 20:50. Tried thick and thin dashpot oil. No change, still sucked. See earlier posts. Tony. Thanks for the confirmation that drilling the main cap, doesn't result in it cracking. I don't recall you posting that before though. I've been asking people, but I could have missed your reply somewhere. That's something to consider as a possible too then, but as you say, too little oil in the cover will be as bad as too much. Since I won't be running at high revs, and the oil drains ok in the summer, if I increase the oil drain rate, the chain could get starved in the hot weather. I wouldn't want a snapped chain. :(. For the same reason, even I can drill the block safely, I want to be sure a bigger drain hole doesn't cause a bigger different problem. Malc. Yes, I'd forgotten you used hylomar to 'seal' the retaining plate? And so did Tom looking back. Dissapointing if that hasn't worked :- . How do you know it's still sealed? BTW, what torque setting did you do your camshaft retaining plate bolts to? I read back and see that your oil pressure is 70psi hot. That's essentially normal, and Tom's cold is 60psi, as is Norm's. Both of those suck oil too. Oil pressure is not the issue. It's beginning to look as if I will be tapping my petrol pump blank for a solution after all, and giving up trying to find the root cause. But, NOT YET.

Lawrence Slater

Final test with modified cover. Ready to go.

Lawrence Slater

Here's the result. Same as the others. Load of oil in the breather tube. There's a baffle plate over the entrance hole to the tube that leads to the canister, but that doesn't stop the oil getting into the canister in large quantities. The chain must be flinging plenty in there, but I'm also certain that the cover is pretty full too. http://tinyurl.com/kxc8nqd

Lawrence Slater

I think both guy and slatterly raise a very good and valid point/question ""Paraphrasing"" What happens during the rest of the year along with when the oil reaches normal operating temp ? Granted the oil will flow better during the 1st 5 minutes from the time the key is turned, but what will happen from 10 min on until the engine is turned off. I can see the value of slattrys suggestion for drilling the mains on a race engine that runs at very high constant revs, but id think to much oil flow for a street engine that rare runs at high revs.would provide to much oil flow, and make even bigger problems Prop

Prop and the Blackhole Midget

Concerning my own experment the other day that goes hand in hand with your situation Here would be an interesting experment, take various 20/50 motor oils, and put them in the freezer for several hours and test there viscousities and then agian when the reach room temp Esp thur drain holes the same size as what the oil has to pass thur in our engine Prop

Prop and the Blackhole Midget

To add to my above .... what happens if you correct this at cold temps and the engine is warmed up or warm weather On my work truck it has 240,000 miles ... the last 2 summers ive had to use 20/50 oil instead of 10/30, because the hotter oil is to thin and I loose to much oil pressure do to worn bearing shells I assume. My fear is if you fix the engine to not suck oil in the 1st 5 min of an ice cold engine you could have an engine that will have low oil pressure when the engine heats up to normal operating temp Prop

Prop and the Blackhole Midget

Prop, hold up a while? :) I'm trying to get in some posts of results all in a sequence, without going off, AGAIN, on a discussion about things that have been discussed before, in between. :).

Lawrence Slater

I think it unlikely that drilling the mains drain holes to the next size up (+1/64th?) would result in the cam chain ever being starved of oil. Yes they are prone to wear at high mileage but that is surely due to stretching because of the continual snatching at the links with constantly changing revs. As far as lubrication of the chain is concerned I doubt very much that it needs to run half submerged. Just a good flow of oil from the cam bearing, plus that oil being thrown around by the rotating parts will ensure that the chain is continually soaked in oil. Compare that to how much lubrication a motorbike rear chain gets, and that being run in a much harsher environment! Not sure how one might experimentally test this one Lawrence, but I still think that your mystery contributory fault could be to do with the oil feed route beyond the cam bearing supply, to the rockers.

Guy W

I give up. lol. This thread will just get longer and longer and longer, and more and more and more difficult to follow, as we all go back over and over and over and over and over and over and over and over and over and over and over again, things that have been discussed before. :) The drains are fixed in size. ALL the have the same size drain holes. But NOT all suck oil. I agree. How could you test making them bigger? So I'd rathe rnot risk it. And as a 'fix' rather than the cause, I'd rather leave that aside for now, as I've said about all "fixes", umpteen times before. All the Spridget 1275 engines are spec'd to 20:50 engine oil. But NOT all suck oil. Loads of Spridget 1275 engines run with higher than 60 psi oil pressure. But NOT all suck oil. Norm's engine runs at 60psi. Tom's engine runs at 60psi. Malc's engine runs at 70psi. All three suck oil. So oil pressure is a red herring. But anyway: ---- If the oil pressure is high, either it's high because of a 'blockage' upstream of the camshaft front bearing/journal, in which case the camshaft front bearing would be running at a much reduced oil pressure. In which case it couldn't be the cause of too much oil in the TCC. Or, it's because the camshaft front bearing/journal IS the blockage, in which case the front bearing AND the rockers would be starved of oil. And again, this wouldn't be the cause of too much oil in the TCC. Or, the feed to the rockers, or the rockers themselves are the blockage. In which case the rockers would be starved of oil, and that would have shown up by now. I checked mine many times, and there has ALWAYS been plenty of oil in the rockers. When I stripped my spare engine last year, I confirmed that the oil feed in the block/head was clear, and checked the rocker shaft for scoring and signs of oil starvation too. None found. Back to the future? ;)

Lawrence Slater

Lawrence you think you have put some of these issues to bed and you therefore close your mind to other possibilities. Now this may be fine whilst you concentrate on the elements that you are currently researching. But as the conditions needed to create the oil cloud appear to be fairly marginal I don't think you should be so ready to rule out possibilities so readily. If you don't like others raising issues that you may think are resolved, then maybe you should conduct your on-going research "off line" and come back when you have your single definitive answer! ;-) Here's another thought though. I am not going to re-read stuff but I think you have said that the oil cloud from your car always occurs a the same place. And you put this down to it being the distance that it takes to warm the car to the "goldilocks point". Sounds plausible. But if the weather is colder and the oil starts out at a lower temperature, (e.g.5 degs. colder) does the distance you can drive increase? Or decrease? Or not change at all, in which case why not?

Guy W

Lawrence, Can you add a trap to your vent tube to allow slugs of oil to drop out of the flow, basically a larger diameter chamber where the gas velocity drops and allows the oil to settle, this could then be allowed to drain back into the fuel pump boss potentially with a large diameter hose so gas speed is slow and doesn't impede draining. BTW in my limited experience the rocker assembly in good condition doesn't require much oil flow. I base this on having rebuilt a pressed steel rocker set with new bushes and hardened rocker shaft and removing the rocker cover cap didn't result in a shower of oil, also the main 1" OD vent I added to the rocker cover didn't result in loss of any significant quantity of oil to the catch tank. Enough oil obviously did get into the rocker cover to lube the rockers and push rods as they didn't wear any more than normal. The rocker assembly and shaft is known as a weak point and in the normal way does flow more oil as the bearings and shaft wears and so does splash around in the cover. Posted from Chrome under Ubuntu Linux as my other Firefox installation has an issue with longer threads which I haven't resolved yet but have things in hand to upgrade to a newer version of the OS in the near future.

David Billington

Hahaha... well I did suspend my right to free speech. Prop

Prop and the Blackhole Midget

Just to confirm.... On the engines that DONT SUCK, what are there environmental conditions Im assuming,... 1. outside year round 2. have no blockage/insulation from the weather elements 3. Parked on level ground not front upward 4.are not allowed to warm up before driving 5. Oil kept to maximum level with 20/50 6. Oil is not dulited with petro fuel 7. Outside temp is at least 20 degrees F. 8. Engines are fairly new and fairly well sealed against blowby Is this the condition of the engines and there enviorments that are not sucking oil? My thought is to now, look at the engines that DONT SUCK OIL, for a common link that prevents them from sucking Or it could be that they do suck oil but the owners do not know and assume theres dont... I was in this camp until just last week. Prop Prop

Prop and the Blackhole Midget

Guy. " --you therefore close your mind to other possibilities." No. Those are the SAME possibilities that I've elliminated time after time after time aft------ . How many times should I keep reconsidering them, before I move on to the next possibility, which btw, "offline" I've been experimenting with, before trying to post the results here, in a readable contiguous fashion? But that I realise, is impossible. " ---as the conditions needed to create the oil cloud appear to be fairly marginal --- " lol. Yeah sure, IF you call having a TCC brim full of oil marginal. " -- you have said that the oil cloud from your car always occurs a the same place." Nope, I didn't say that. I said in some of my results, that sucking occured in the same place. But in others, I said it sucked at a different place. I now refer you to all the answer I gave in previous posts. Prop. The engines that DON'T suck oil, DON'T CARE what the environmental conditions are. They simply DON'T suck oil. Only the suckers do, and all they need is COLD; AND a TCC full or near full of nice thick oil. David. It's the same answer. NON oil sucking engines don't have a chamber -- other than the breather canister -- where the oil can drop out. So why should I need one if they don't? As a fix, that's pretty much what Tom has done. And Malc has a catch can inline that collect the oil. But I'm working on prevention in the original system. I guess if BMC/BL had made the existing breather canister larger, that might fix the problem. But since presumably it didn't exist when the cars left the factory, something must have changed. I'm looking for the changed element.

Lawrence Slater

And very quickly, BEFORE someone else gets in again. Question. What would happen do you think, if against a hard FLAT steel plate, the screws were tightened? PS, those post looking things at each end, are my poor drawings of screws.

Lawrence Slater

I wasn't suggesting that having a TCC fill of oil ead marginal. But that whatever it is that causes the TCC to gradually overfill could be.

Guy W

Prop. The engines that DON'T suck oil, DON'T CARE what the environmental conditions are. They simply DON'T suck oil. Only the suckers do, and all they need is COLD; AND a TCC full or near full of nice thick oil. Id think thats exactly where you should start... there doing something differant then all the engined o that are sucking Find out what that is, and your problem is solved....at this point, I dont think you can gleen any other info from engines that are sucking Prop

Prop and the Blackhole Midget

To answer my own question then. "What would happen do you think, if against a hard FLAT steel plate, the screws were tightened?" -- Refer to the picture I posted 2 posts ago. This is what can happen, -- provided the screws are tightened enough. Just in case that isn't clear enough. The feeler blades go all the way through to the shaft. One blade is a loose 3.5 thou", and the other is a loose 5 thou" but can take a 6 thou" interference fit. Question. Malc, you may have missed my earlier question to you. So I'll repeat it. ----- "BTW, what torque setting did you do your camshaft retaining plate bolts to?" ----- Same question to Tom and Norm, and to you too Prop.

Lawrence Slater

Whoa Gents, lets back off a little.... Prop, as Lawrence only has engines that suck oil he's not in a position to work on/strip and check one that doesn't. Therefore testing what he has is the only way forward for him. Unless someone want to donate a non sucking engine step by step elimination is the way to go and he might get lucky ;) Guy, I get that many thing with a small variance might add up to Lawrence never finding the magic bullet but he has to finish what he's started to reach his own conclusion. Recovering old ground is a little futile until all other possible causes have been checked and discounted. I'm sure by now we all know there are many ways to fix the symptoms, lets support Lawrence in his efforts to find the cause. Lawrence, was that last question rhetorical? if not, my take on it is..... When the bolts are tightened the harder steel will deform the softer white metal to the point where the load across the surface area of the steel is above the point of elasticity of the steel. Thereafter the steel will deform probably (but i'm not sure..) by bending from the centre to the bolt positions. So Lawrence whats next? Cam plate fit and end float? measurements on the front cam bearing running clearances, cam oil groove size to work out the volume delivered..... Watching with interest..... MGmike

M McAndrew

Lawrence We assume your engine is the same as other non-sucking engines in it's build from new So looking at pictures of your engine the only non standard parts appear to be the aircleaners which if I'm not mistaken are the oil soaked type Not saying it is but could it be possible that there is too much oil in the filters making the breather suck harder than normal at part throttle It would be interesting -as a little project to disconnect one of the breather ports and get a vac reading on the port at part throttle on the road at the time when oil sucking normally occurs and compare it to a car with ordinary paper filters Having said this I am expecting you to tell me that your other car has std. filters but it's just a thought A non standard mod I thought of (which I know is getting away from what you are trying to get to the bottom of) Would be to attach/weld a little baffle/scraper to the engine plate in behind the bottom sprocket just after the drain holes (clockwise) to stop the oil on the inside of the sprocket being dragged around and around with the momentum of everything and going straight past the drains. If this was a good fit to the cap and as close to the sprocket,chain as possible it might just be enough to let enough oil drain back to stop the cover filling up. The timing chain tensioner acts as a bit of a baffle but it is up fairly high and I think a little plate in behind the sprocket should work nicely AH The timing chain tensioner,- If that is an aftermarket unit some of them had the backing plate slotted for multi fit purpouses if I remember correctly. Might be worth pulling it off and making sure the oilpressure isn't escaping from a missfitting mounting plate with an overlapping oil gallery or something as that would definatley add to the volume of oil in the cover.There are little paper gaskets for these which are often overlooked, I never fit them to Bs but in this case they should probably be there or at least sealed up Also on the end of the tensioner some have a bung for fitting an Allen key to wind/release the tensioner. I've seen more than one that have been assembled without the bung being refitted--result-lots of oil willy

William Revit

Lawrence My humble appologies No oil pressure fed tensioner on A series then Sorry I get a bit carried away willy

William Revit

Lawrence, Not sure I did use a torque wrench - the car and my tools are stored at the GF's - I'll be there later today so will have a look and let you know, if the manual specified a number and I have a wrench that goes that low I would have used it, otherwise i would have just done it by 'feel'. I see where you are going with this, so I will look at the possibility of removing my cover and checking the end float clearance - can't promise I don't what she has planned ! Malc

Malc Gilliver

Mike. Thankee kindly sir for those warm words. ;). You're right. As you can see from my previous picture of the two shots of my camshaft endplate, there is a gap under it. How did that gap get there? By over tightening the bolts. Exactly as you describe, the softer white metal has been squeezed out, and crushed under the steel on top by the bolts, against the hard steel of the front engine plate. But as you travel along to the centres, between the bolts, there is no force to clamp the plate. So it arches. This does TWO things. 1) It produces a gap between the retaining plate, and the front face of the engine plate. No gap should exist. 2) It prevents the WHOLE of the face of the white metal, from running parallel with the face of the bearing surface of the camshaft. This results in the gap for the end float, being different, depending on where you measure it. The oil hole in the retaining plate, is SUPPOSED to be the control for the oil flow to the TCC. Once per revolution, the oil groove in the camshaft lines up with it. The rest of the time, the hole should be completely obscured by the contact with the face of the camshaft, and no oil flow through it. However. With a bent retaining plate. Not only can oil flow from under the sides of the retaining plate, but oil ALSO flows through the oil delivery hole, AND through the LARGE centre hole in the retaining plate. The tap is open permanently. If you cast your minds back to previous threads, in particular the one where I posted picture of my SPARE engine strip, you'll find I was saying the same thing. But now it is far clearer, why the retaining plate has such characteristic markings on it's face. The locations around the bolts are crushed. The plate is bent. The camshaft only makes contact with the plate at 3 points, instead of uniformly around the whole bearing surface of the plate. The length of the points of contact, depend on how bent the retaining plate is. And that appears to depend, on how tight the bolts were done up. The book quotes 8 lbft of torque for those bolts. (BMC). -- I found it once, but can't find it again. --. Anyway. 8 lbft doesn't feel like much. Especially if you use a long torque wrench. Even if a 0-60 wrench is accurate anyway at it's lower end, I almost certainly went to more like 10+, because it felt so loose. I said the same thing in the previous threads, and drew the same conclusions, but now I have proof positive, that the bolts have been over tight. Here is a picture of the plate from THIS engine. The one I've been working on. See how small the contact points are? See how crushed it is?

Lawrence Slater

A bit clearer?

Lawrence Slater

And this?

Lawrence Slater

You might also remember my front engine plate from my SPARE engine strip. I said, that where the oil was flowing UNDER the areas between the bolts holding the retaining plate to the face of the engine plate, the face of the engine plate looked like it had been erroded. So does this engine plate. The oil is hot, under pressure, and contains contaminants. it looks very much to me as if it has 'worn' away the edges of the plate, facilitating the escape of oil. Here's a picture of my SPARE engine plate to remind you.

Lawrence Slater

Isn't that distorted plate the best explanation as to cause discovered so far? As a possible guilty party, you have always cited camshaft bearing passing too much oil as a likely candidate.

Graeme Williams

Nope Graeme. THIS IS PRECISELY what I said when I discovered it back when I stripped my spare engine. I used the word Ureka, I believe. The bearings are also suspect, and remain so, until proved innocent. And would it help to compare a used FACTORY original camshaft retaining plate, with, in this case the one from my REBUILT SPARE engine? Again, I posted this before too. See how the factory original is worn uniformly all the way around? This plate is flat. Mine by contrast isn't flat, and is only partly worn, in 3 locations. This is my SPARE engine to remind you. My CURRENT engine camshaft retaining plate, is worse, as you can see in the previous pictures. AND. You may recall, that I've NOT been in the habit of renewing these, IF the endfloat was in spec when I rebuilt the engine. Again, I surmised in the previous threads, that this was very likely a long way towards an explanation of oil sucking. re-using an already bent plate, overtightening it AGAIN, bending it MORE. At the very least, this can't be good. But on an engine, such as the early 948/1098, where there is no TCC breather connected, who'd ever suspect that these marks are significant at all?

Lawrence Slater

Just for the avoidence of doubt you understand :). Posted 23 February 2012 at 03:08:05 UK time "Lawrence Slater, Kent, United Kingdom, slaterlpj@btconnect.com Here in this composite picture is what I believe, with conviction :), to be the root of the problem. ---- Certainly the case on my engine, and I suspect there must be a cam bearing connection on others with this problem too IMO, since this is where the oil comes from. -- . :) Note the oil feed hole, and the camshaft oil feed groove, lined up with it. Note the badly and unevenly worn end plate bearing surface. Parts of the end plate bearing surface, haven't been in contact with the camshaft at all, and are as new. Where it is worn, it is grooved quite deeply. It appears not to be flat. So even when the camshaft face is pulled up to the end plate, into the wear grooves, and end float reduced to zero at those points, there are still significant gaps between the face of the camshaft, and the end plate. Through these gaps, oil under pressure, can be pushed into the timing cover, even when the oil feed hole and groove aren't aligned, and no(little) oil should flow." Continues with the remainder of the post and the rest of the very long thread back in 2012.

Lawrence Slater

Now the FINAL proof, will be to fit a new camshaft retaining plate, and ENSURE that it is FLAT. But. HOW to do that? What tightness for the bolts? Thread lock too, as they won't be that tight? Buy a LOW RANGE torque wrench? 0-20 or 0-15 lbft? I'm also going to fit a steel plate/washer OVER the camshaft retaining plate, to spread the clamping load of the bolts. I'll have to make it. Here's what I posted back in 2012 too. Posted 29 February 2012 at 19:18:51 UK time None of this may fix it. I may be COMPLETELY wrong. But it's the most logical, and if nothing else, it means the only way left, is to make modifications to the breather system.

Lawrence Slater

A well known Mini engine builder has suggested (on another site) that the cam retaining plate isn't flat even new - and his technique was to assemble the plate together with the timing gear and then give it a smack with a copper faced mallet to flatten it. 'As a 'trick' when building engines in order to set the camshaft retaining plate rap the end of the camshaft sprocket with a copper mallet. If you are using a new thrust plate they are usually not flat meaning that the apparent installed thicknes is greater meaning less clearance. Raping the end of the cam with all the sprocket and cam nut torque up will straighten a warped plate meaning an increase in clerance by a few thou. DON'T OVER DO IT!!! Prefered endfloat is 0.003 to 0.007", as Roy has stated 0.004" to 0.006" is much nicer.' If the only means of oil entering the timing cover is the hole in the plate and the diametrical clearance to the front bearing is between the recommended .001 to .002 in it's difficult to imagine how the thing can overfill with one squirt per rotation. If however,in addition to a bent retaining plate the front bearing clearance is greater (undersized due to bearing wear or journal) then the supposedly controlled one squirt per rotation becomes a continuous leak, and would increase even more if the endfloat is greater than it should be. So it would seem that we're left with reaming the front bearing to suit the particular cam installed so diametrical clearance is only 1 to 2 thou,installing a new plate that's been flattened if necessaty and sealed, and then use a dial gauge to measure end float lies somewhere between 4 to 6 thou.

Fergus Pollock

That's a good find Fergus. Excellent. I asked that very question many moons ago. But we all considered that they were flat when new, or as flat as mattered anyway. But to find that some are NOT flat when new, could well explain why the oil sucking frequency amongst 1275 Spridget engines, varies so much. Maybe it's all pot luck as to whether you get a new flat plate, combined with, and exacerbated by overtightening of the bolts. I've also since wondered, if the thickness of the backing steel, has 'thinned', since original production. Maybe, they simply aren't as strong, and bend more easily than they used to? As regards the oil flow, -- leak. I now consider, that even if the diametrical clearance twixt journal and the bearing is in spec, there could still be an oversuppy with a bent plate. Nay, WOULD be an oversupply. It's inevitable. The circumfrential groove in the camshaft picks up the oil from the front main journal and distributes it around the camshaft journal/bearing. The rear facing groove is connected to the circumfrential groove, and, ONCE per revolution, it aligns with the upwards facing hole in the block, to carry oil to the rockers. The FORWARD facing groove in the camshaft, collects it's oil, only from the general oil supply circulating around the camshaft journal/bearing. And again, ONCE per revolution, it aligns with a hole, -- the retaining plate hole. That should be the only means of escape for the oil from the forward facing groove. BUT, ONLY, if the front face of the camshaft is held against the FLAT face of the retaining plate, -- as it should be, caused by the thrust from driving the distriburor. IF the retaining plate ISN'T flat, then the oil can leave the end of the forward facing groove constantly. Hence, oversupplying the TCC with oil.

Lawrence Slater

Here's what I mean. if the plate is bent, then the oil will flow irrespective the hole meeting the groove.

Lawrence Slater

I think I mentioned before that, when building my first A35 engine, I bought a new camshaft retaining plate from a large Mini specialist in London. When fitted, there was no endfloat at all. I ended up re-using the original. I do have some NOS genuine plates, which I could check for flatness...if I get time to dig them out. Overtightening of the screws is probably the main factor in distortion, although ISTR that the plate on the 'development' engine also had the odd wear pattern. There should be 'shakeproof' washers under the screws.

Dave O'Neill 2

Lawrence I think you might be getting there :D Lawrence said:- "I'm also going to fit a steel plate/washer OVER the camshaft retaining plate, to spread the clamping load of the bolts" IMHO the size of the washer at the most important points between the bolts is unlikely to add much extra force where you need it. I would be considering the addition of 3 x Z clamps if theres room (which I think there should be). Sizing them will be a challenge but they could be made to allow for shimming where required. Best of.... MGmike

M McAndrew

"Z clamps"? What do they look like Mike? Hi Dave, funny you should mention that engine and it's camshaft endplate. I think I asked you before, but do you have any more history of exactly where that engine came from? Looking at it again, with my more thorough undertanding, I can see that it (the cam endplate) too is bent, and crushed at the bolt holes. Not only that, on the reverse, it has only been in contact with the nose of the cam sprocket at 3 distinct places, right in the middle of the spans between the bolts. So the camshaft contacted it adjacent to the bolt holes, and the sprocket in between them, on the other side of course. It's arched. So now considering that timing cover too, as they both came from the same engine, I'm thinking (pretty sure) that was an attempt to cure this very problem. It looks like too, that the long neck had been attached at various points. Whoever it was, probably gave up.

Lawrence Slater

I dont see it... If this was the cause, then why does it quit sucking so soon... the sucking only occures for the 1st. 5 minutes, then its fine. If the problem was a warped end plate then the sucking.would be non stop and consistant. The only way for this theory to work is if the engine heats up faster then we expect and there is distortion in the cam plate to seal the engine up Also with this warped cam plate it would also suck during the summer Now if you will be so kind as to lay your heart on the table ill be happy to stomp all over.it as well....haha As to your qustion ... I have to quote mike, only without the GF. """"Not sure I did use a torque wrench - the car and my tools are stored at the GF's - I'll be there later today so will have a look and let you know, if the manual specified a number and I have a wrench that goes that low I would have used it, otherwise i would have just done it by 'feel'.""" Prop

Prop and the Blackhole Midget

" --- heats up faster then we expect -- " Not at all Prop. It's EXACTLY what 'I' expect. The trouble is, that you haven't read everything, you've admitted as much a number of times. You don't understand it because you are missing all the other information, which I'm not going to repeat again here. Just read this thread from the beginning and all the others too, and then you will understand it all. Meanwhile, I'll repeat my last post. "Z clamps"? What do they look like Mike? Hi Dave, funny you should mention that engine and it's camshaft endplate. I think I asked you before, but do you have any more history of exactly where that engine came from? Looking at it again, with my more thorough undertanding, I can see that it (the cam endplate) too is bent, and crushed at the bolt holes. Not only that, on the reverse, it has only been in contact with the nose of the cam sprocket at 3 distinct places, right in the middle of the spans between the bolts. So the camshaft contacted it adjacent to the bolt holes, and the sprocket in between them, on the other side of course. It's arched. So now considering that timing cover too, as they both came from the same engine, I'm thinking (pretty sure) that was an attempt to cure this very problem. It looks like too, that the long neck had been attached at various points. Whoever it was, probably gave up.

Lawrence Slater

Lawrence, In the distant past I think you discussed the installation of the front cam bearing (not the plate) but I haven't seen you mention it lately. Isn't it true that if the bearing is driven into the block rather than flush with the block face, this also would give full time flow to the hole by feeding in the area created by the bearing recession? Is there a factory cam bearing drift, and if so is it shouldered to stop the bearing at the face of the block? It looks like some of those cam plates have steel lined bolt holes to try to prevent crushing. Also, for 8 ft-lb torque you would be better off getting an in-lb wrench instead of a low value ft-lb. If using lock washers, using the German style wave washers should be preferred since a split washer is more likely to twist the metal as it digs in while being turned. Charley

C R Huff

Having meassured it, there is enough room under the sprocket, to fit a 4mm steel plate/washer over the top of the retaining plate. I don't think that would bend, and will keep the whole retaining plate clamped flat to the engine plate.

Lawrence Slater

Lawrence, In addition to what I said above, is the construction of the engine such that you need to see if the threads for the plate retainer can be pulled up proud of the face similar to what head studs do in the top of the block? Charley

C R Huff

Hi Charley. Yup your right. Before I stripped my spare engine, that was my thinking. I didn't know the condition of the retaining plate then. My spare engine front bearing is slightly recessed, but not as much as I expected. This engine looks about the same. I have a picture of my block with the bearing greatly recessed, but it's a long time since the 80's, it appears that I had that put right. You're also right, if recessed there will be free flowing oil in the recess, so I agree, the bearing should be flush. I've bought a set of solid, as opposed to split ring beaings and will use a cut down camshaft as a guide when i drift it in. When I do it, I'll post it. "It looks like some of those cam plates have steel lined bolt holes to try to prevent crushing." Yes they do. But they are crushed too. Not too tough are they? :). Edit. Yup, the threads on my spare engine were indeed pulled proud. This could potentially keep the front engine plate from sitting flat. So they need to be flattened off. That's also evidence for the bolts having been overtightened I reckon.

Lawrence Slater

PS. I've just inspected a NEW endplate. No crush sleeve, just the laminate of steel on white metal.

Lawrence Slater

PS again. Just looked at the "crush sleeves" under a magnifier. They aren't. It is the 'flow' of white metal, squeezed into the gap between the hole in the engine front plate and the bolt.

Lawrence Slater

Here.

Lawrence Slater

Well done Lawrence. Do you think this is the culprit then after all? I thought you were still looking for some other fault. Does the groove on your camshaft extend right through to the front face of the bearing to eject oil through the oil delivery hole in the retaining plate? From memory, I thought on mine the groove stopped short, but aligned with a notch in the cam bearing instead. This would act as a pulsing valve and make the clearance on a worn retaining plate less significant, unless of course the cam journal/ cam bearing wear was excessive.

Guy W

Guy, as I said to Graeme, a number of posts back, I decided this was the prime culprit back in 2012. (Posted 23 February 2012 at 03:08:05 UK time). I just needed a 2nd engine to confirm it. Now I've stripped my current engine, I can. I've been saying so often enough, but you have to have seen all my posts, and there have been a lot of them in a lot of threads. Scroll back to Posted 17 January 2015 at 14:54:05 UK time. You can see the groove on these camshafts goes all the way to the front. There are 3 grooves in total, you can see 2 in my pictures, but my description describes them all.

Lawrence Slater

"I decided this was the prime culprit back in 2012" Yes, I remembered that, which is why I thought you were looking for something else now. Back in 2012 I posted photos of my cam retaining plate, showing very similar marks, distortion and wear. Reposted here again. My conclusion at the time was that the distortion of the white metal is more a result of a hammering action from the cam, than simple overtightening. Not that that matters so much. Distortion like that is bound to result in excessive oil leakage.

Guy W

And the photo! This engine didn't suck oil, despite the considerable cam retaining plate wear.

Guy W

A WORD OF CAUTION. I should say that this comes with a caveat. It's not over till the fat lady sings. It's not a fix, until I stop my engine sucking. As much as I consider myself to be a clever sod, and I do, :), I know that there are way smarter, better skilled people out there than me. What has always amazed me therefore, is that nobody else has ever solved this. And that means, that I'm not quite as confident about this as I'd like to be. So until I bolt on a new flat plate, and run the engine, and it doesn't suck oil, the question remains open. Edit. Yes guy. And you also said that that endplate was from a 948 frog, that doesn't breath from the timing cover!.

Lawrence Slater

Posted 17 November 2013 at 16:31:14 UK time "<<Guy's picture in particular shows a dry oil congealed front engine plate. It had obviously not been bathed in a constant supply of liquid oil>> Don't put too much score in this Lawrence. That engine is a 948 for my Frog, last taxed for the road in 1984! So the fact there is any liquid oil on the front cam bearing is quite surprising! ;-)" If the camshaft was hammering back and forth as much as to distort the plate, you'd sure hear it I reckon. And the distributor timing, which depends on controlled endfloat, would be all over the place too.

Lawrence Slater

Better memory than me then Lawrence! I know my engine doesn't suck oil, but forgot which engine that cam plate was off as I have stripped and rebuilt several now.

Guy W

:). Is that a concession then, that I might be right? ;)

Lawrence Slater

Lawrence, It's Saturday evening,,,, I'm having a few tipples tonight..... will provide info tomoz.. Best of... MGmike

M McAndrew

Lawrence, I always thought you had found your problem 2 years ago! But as you seemed not to be convinced I believe for it to blow oil it must be a compound effect of other factors as well

Guy W

It doesn't BLOW oil Guy, it sucks. lol. And hardly Guy. I think you need to re-read the threads. :). I was pretty sure it was the endplate, subject to me confirming it by stripping my current engine, which I've now done. I was also adamant the TCC was filling with oil. It was your goodself among many others, who had most doubts, about not only WHAT was happening, but HOW too. Mists vapours and slugs of oil were the constant cry.;). I think I've spent the vast majority of my posts, trying to argue against the tide of the status quo of opinions, that this is all caused by blow by, and mists, and the wrong type of suction etc. lol. 17 February 2012 at 23:06:49 UK time, I wrote.--- "For the oil to be sucked up out of the timing cover in a solid column, there must be an excess amount of oil inside the cover, enough to reach the internal opening of the oil seperator. What I don't know is how it got there in excess quantity, and why it didn't drain away sufficiently to prevent filling the timing chain cover " 20 February 2012 at 21:22:39 UK time, I began speculating that it was the cam endplate. "I admit to reusing my cam cover plate, I don't recall ever replacing it, as it looked ok to me and I was tight. :)." 22 February 2012 at 22:35:51 UK time I wrote. "The end plate is badly worn and end float is at least 0.013 inch." 23 February 2012 at 03:08:05 UK time I wrote. "Here in this composite picture is what I believe, with conviction :), to be the root of the problem." I posted pictures of my distorted camshaft endplate. It was others who needed convincing, not me. And you still won't entirely accept it. Fair enough, no reason you should, but I'm not the doubter here :). The PRIME cause, subject to my caveat of actually fixinf it, is the distorted endplate. If that factor isn't present, then none of the other factors will cause oil sucking. Clearly the endplate can be more or less, "bent". If the endplate is LESS bent, then it's quite likely that a small change in other factors will have an effect. If the endplate is MORE bent, just like mine definitely is, then no amount of tinkering around with suction or the oil filler cap, or anything else, will stop it sucking if the PCV is connected as it should be. However. There is STILL one mystery. Why does the level in the sump stop the sucking? obviously if it is so low as to lose oil pressure, there won't be any sucking. But all it appears to need is to reach minimum, and then it appears to stop. That's a small reason, that I myself won't be entirely certain, until I actually prevent the oil sucking. I think that's quite reasonable. Enjoy the tipples Mike. :).

Lawrence Slater

Lawrence, l have NEVER doubted that your engines suck oil. And l have NEVER suggested that in your case the problem was oil vapour, blocked breather tubes or any of the other conditions that can produce impressive clouds of blue. Your engines suck. No argument about that! I cannot re-read the earlier long thread on the subject. Part way through, with these mega-threads, my computer gives up and won't open the messages. It seems worse when the thread contains lots if photos.

Guy W

Guy, time for an upgrade. More Mhz and Mby , it's a bit like gas flowing a head for more bhp or fitting a K series. lol... Best of...... MGmike PS. had more tipples than I should have and I'm off to bed...

M McAndrew

Lawrence I've just been going through an old email from 2012, when I was sending you an engine front-plate. It seems I also sent you the cam plate from the test-bed engine... "I can't find any new cam plates, but I will include the one which came off the engine. It is only showing minimal wear."

Dave O'Neill 2

The analogy is good Mike, but its not the engine ( 4 month old quad-core computer), its the air intake system - the network speeds of just 1.4Mb/s max, and intermittent at that, which is the problem!

Guy W

Sure Guy. I'll believe you. You accepted it right from the get go. ;). Hangover Mike? ;). Yup Dave you did. Along with the modified TCC, without which prop (no pun intended but it's a good one anyway) I couldn't have made my little movies. :). That's how I was able to post the pictures of it below and re-examine it and really understand why they develop those wear marks. Clearly the whole of the white metal face is a bearing surface, and clearly the intention is that the whole of that surface is intended to be in contact with the camshaft face. Imagine that only a small section of the main bearing contacted the journal. How efficient would that be? On close examination of my spare engine camshaft, and the one in my Sprite at the moment, I can see distinct wear in the face, caused by the limited spread of the load. Instead of the smooth polished surface you'd expect from polished steel against a white metal bearing bathed in oil, particularly the one in my Sprite, is scored and worn. Not surprising now I see what's happening. Again, if you don't breathe from the TCC, this probably doesn't matter much, -- for road use anyway. The camshaft and endplate last so long anyway, that even if the endplate is bolted on distorted, it doesn't matter much. If there's too much oil in the TCC, that doesn't matter either. Many versions of the A-series weren't inline and had the breather from the side plus the g/box. So in that community, it's also gone largely unnoticed. Except that, as Fergus pointed out, and you found, some of the plates appeared to be less than flat when new. But as long as a satisfactory end-float result could be obtained, who cared? It seems only in the world of 1275 Spridgets to have caused a problem. Various get arounds have been applied, but the cause never identified, until now, -- I "HOPE". lol. Otherwise, my neck is so far out on a limb -- to mix metaphores --, I'm going to lose it and fall off. LOL.

Lawrence Slater

Lawrence: why don't you just fit the new endplate and see if it stops the oil build up? I presume, as you are still talking about the theoretical effects of distortion on the end plate that you have still to do that (or was that reported elsewhere in this megathread?)

Graeme Williams

Because I want to first establish EXACTLY how 'tight' the bolts should be. AND I have no means yet, of measuring ACCURATELY how tight they would be if I used my current torque wrenches. 0-60lbft. Can ANYONE point me to the exact torque setting in a w/shop manual. I can't find it. The figure I got of 8lbft, I got from a mini site. But it may just have been 'folklore' rather than the gospel according to BMC. Have you read the description in the BMC manuals, of fitting the camshaft endplate? No torque or tightness figure mentioned. And yet, it's obvious now, that making the bolts over tight, compresses the ends, and arches the plate. So I'm not going to waste another one, until I can be sure I won't instantly f*ck it up. I could do them just a little over finger tight, maybe with some thread lock. But it doesn't take much imagination to know what will happen if the sprocket comes off because the bolts fall out. SO I HAVE A CUNNING PLAN. I'm going to use one of my OLD plates, in fact the one I just removed. I'm going to SEAL JUST THE OIL FEED HOLE, and bolt it back on again, good and tight and bent. My proposal is that the chain will continue to get all the oil it needs. I'll be watching through my little plastic window. Watch this space for a new exciting video. lol.

Lawrence Slater

It's my understanding that a torque wrench is most accurate in it's mid range. 8lbft = 96 inch pounds. So what range wrench is suitable for this? 0-20 lbft? 0- 500 inch pound? Where are all you engineers? Answer please? :) Pretty please.

Lawrence Slater

I can find nothing in the BMC manual for Midget or MGB, which uses a similar arrangement. I've been through lots of Haynes manuals for A-series engine cars, and the only one that has a figure listed is for the Metro - 8lb/ft. Edit: I don't see what blocking the oil feed hole will prove.

Dave O'Neill 2

In the absence of a torque wrench you can get a pretty accurate figure using a ring spanner and a weighed lump of lead hung off it on a wire. Or a luggage / fisherman's spring balance.

Guy W

Yup, that sounds like a plan Guy. Also a free one :). Dave. With the oil feed hole blocked off completely, a continuing supply of oil still entering the TCC, will prove just how much is leaking past the plate, that shouldn't be. I want to know if the TCC will still fill up, and if there will still be oil entering the breather tube. All at no cost, other than time and the petrol to run the engine. What's to lose?

Lawrence Slater

Lawrence My old book says 8 ft/lb Also MGB runs a very similar system with no oil hole in the plate I've been talking to an old fella today (well older than me anyway) He used to work on a team of racing minis Well you have probably discovered this but I'll pass it on anyway just in case He told me that the later non-sidecover 1275 blocks have a different cambearing set compared to all the earlier motors and if you fit the early bearing to the later (your) block) it has to sit too far back in the block to get the oil supply from the main bearing to line up at all It's got something to do with the offset of the holes and the bearing has to be fitted with the little hole to the top and the slotted hole to the main bearing feed hole He has always used the lining up of the top hole as a guide as to how far to push them in Also when I mentioned about your plate he said he had always used Bellville washers(whatever they are) and locktabs and never had a problem BUT they were minis willy

William Revit

Hey Willy. " --later non-sidecover 1275 blocks have a different cambearing set compared to all the earlier motors and if you fit the early bearing to the later (your) block) it has to sit too far back in the block to get the oil supply from the main bearing to line up at all " That would be like this then. This was the result when I FIRST had my cam bearings replaced back in the early 1980's. I took this picture at the time (on an old SLR) because I was so convinced that it was wrong. But the machine shop, and others I asked, said it was right. My gut told me it was wrong. That MAY be the bearing that's still in my current engine, but I recall either having it changed, or drifting it forwards a tad to the front, because the rear was hanging out so far it was almost fouling the follower. Now some might understand more clearly my thinking, prior to my seeing the bent camshaft endplates. And now, with your tales from the old fella, you've refreshed my interest in the this as a cause; But, combined with the bent camplates. Which W/S manual do you have the confirms the 8lbft?

Lawrence Slater

Bugger, I forgot the picture. Here it is, read the previous post for explanation.

Lawrence Slater

In terms of how tight to do things up in the absence of torque figures I was once told by an old Fleet Air Arm aircraft fitter that they were only allowed to use open ended scanners to do things up as they were told an o/e was made to do that size up to the correct torque. It obviously depends on how strong you are to some extent but seems to have some logic to me especially as they were dealing with a lot of soft alloys. Trev

Trevor Mason

Hi Trev. But even a short spanner will go past 8lbft. It feel like nothing. In the absense of the correct setting, it's my guess I might have first done them to the same as oil pump. 12lbft. But maybe the sump bolts, at 6lb would be a better bet. I've been thinking, again. lol. In the absense of the correct definitive figure, do them just until the plate is firmly held, and then wire the bolt heads together. Course that means obtaining heads with holes in them, or drilling them yourself. Those star washers are supposed to do the trick, but only if tight enough to bite, and maybe that's too tight.

Lawrence Slater

Lawrence, yes a bit delicate today ;D Anyway a picture paints a thousand words... Having looked at the thickness of the cam plate I'm now thinking the design on the left is probably more appropriate. Countersunk screws should prevent any interference problems. Best of... MGmike

M McAndrew

Just for reference, this is what BelleVille washers that willy mentioned are like http://en.wikipedia.org/wiki/Belleville_washer Jim

J Smith

If there's a measurement of 6mm clearance to the cam wheel there might be an opportunity to include a full cover, which would backup and overlap the original thrust plate. This could use countersunk screws flush to the surface,and loctited. Anyone got a lathe?

Fergus Pollock

Hi Fergus. Your professional drawing is much the same as I showed in my crude sketch lower down. However, you have to make the centre hole large enough to accomodate the oil deliver hole WITHIN that centre as I did in my sketch. Not sure if I explained that very well, so here's the real thing to show you what I mean. As for a lathe. I make it by hand. Bit of drilling, grinding and filing. :). I was going to use 4mm, to allow for a bit of clearance margin. Jim, thanks for that. :).

Lawrence Slater

Hi Mike. OK, I get what you mean now. But you've given me an idea. Why not insert studs in the engine plate, instead of clamps in those locations. Drill holes in the retaining plate. The holes in the retaining plate will sit over the studs, and the studs can have nuts added to them to clamp the centres.

Lawrence Slater

OK Version 2

Fergus Pollock

Lawrence, A few posts back you were pondering why running less oil in the sump would stop the oil sucking when the oil pressure indicated that it was not starving for oil. A possible explanation is that if there is less oil in the engine, it does not take as long to heat up and thus flow back out of the chain cover. Jim's Belleville washer is somewhat similar to what I described as German type wave washers. I only called them German because I first saw them on Benz cars. If you decide to make the Fergus design backing plate, you could just add a notch to the inner diameter if that would be easier than increasing the entire inner diameter. If you want to safety tie your bolts, pre-drilled heads are common for aircraft. Do you have access to an aircraft supply house? But, will a straight line from one head to the next interfere with the rotating sprocket? What would the torque be for that bolt if you based it on bolt size? Too much? Charley

C R Huff

So why is the triangular plate, triangular? Why not round like Fergus' support washer. I would presume that the triangular plate is weakest at the narrow bits mid way between the fixing bolts which will just add to the likelihood of it deforming.

Guy W

Charley makes a very good point about less oil heating up quicker. The figures I've seen for the oil pump bolts are between 8 & 9 lb/ft.

Dave O'Neill 2

Guy, Interesting thought on round vs triangle. Maybe it was thought of as a round plate with tabs to make room for the bolts. I noticed that Fergus added the notch to the plate before I could even post my comment about it. So, maybe all our minds are coming together on this oiling problem. Charley

C R Huff

Presumably, with a cold engine start, the oil heats up in advance of the metal engine castings because of the effect of pressure on the oil. Although, come to think of it when I had a car with an oil temp gauge (Alfa) the oil one was the last to start moving.

Guy W

I'm not sure if I'm correct about this, but from my own memory, I think the sump level is only applicable when you have a PCV Valve,aka the mushroom. That's how I started out when I 1st had the sucking problem back in the 80's. That's when I found that as the sump level dropped, the sucking stopped. I dumped the mushroom in favour of a Y piece, and since then I don't think the sump level has much effect in stopping it. I described my london bridges trip recently, where I decided to check the oil before I went. With all the sucking experiments I'd done, the oil was at minimum, but still sucking. But Graeme and Malc both have the mushroom, and both confirm the effect of a low level in the sump, stopping sucking. The mushroom sucks from the manifold. Much higher vacuum. Even at tickover it's high, and Graeme has confirmed that his can suck oil sitting on his drive. So somehow, even there when there is no direct connection to the surface of the oil in the sump, the vacuum is strong enough to pull the oil up, -- until th elevel of oil is so low, that it can't. The moon raises the level of the seas. Could the manifold vacuum be enough to raise the level of the sump oil, and pull it towards the TCC? Fergus. Excellent. Maybe I'll put measurements on it, and take that drawing to a local machine shop. :). Charley. yup, you're right, the wire would foul the sprocket, so that's out. "What would the torque be for that bolt if you based it on bolt size? Too much?" Yup. I reckon you could do at least 15 before they stripped. it's quite possible, that I was. Dave. My copy of BMC w/s manual says 12 on the oil pump for a 1275. It's easy to see why the cam endplate can be so overtightened, if it has been. basically, there's no guidance. Guy. Now you mention that, I seem to remember seeing some cam endplates that ARE round. Or have I imagined that?

Lawrence Slater

I've just found the 12lb figure in my manual. It says 9lb for the 1098.

Dave O'Neill 2

Ah, cheers Dave. And thought so. It was Fergus. :) Posted 29 February 2012 at 14:32:53 UK time "Looking at the dimensions of the cam plate it seems quite a weedy component, and the universal deformation, arching and wear characteristics makes me wonder if the thing can't be improved. So what if it was possible to make a stiffer version - one that didn't bend, wear out and cause oil to escape quite so readily. Given the critical hole centers remain what materials, shape and thickness would it need to be to make it sufficiently rigid? " So where can you buy steel backed white metal plate?

Lawrence Slater

It looks to me that there are two distinct problems with the camplate. One is that it bends between the bolt positions. But the deformation on the corners, around the bolt heads looks to me much more like the white metal has being hammered to deform like that. That would suggest slackness, rather than the bolts being overtightened. Maybe they start off overtightened, which deforms the plate. This allows the cam to move axially too much and this then hammers and deforms the white metal, causing the bolts to slacken and accelerate the process. He answer would be a stiffer cam plate, and locktight!

Guy W

Beep Beep Beep.... Okay time to back up the trolly wagons!!! Lawerance, You were very clear about having NO modificstions ... that the entire purpose of theses massively long and noxious topics was to fix the problem NOT to create a work around, to make this work as intended from the factory Sorry, but NO modifing the cam plate is not an option and should be removed from the table...you can use existing spares or make your own as long as it mirrors the orginal If the game has changed, then the thread is now offically over, ither let the engine warm up 5 minutes or add a KAT engine heater to the lower radiator No no no !!! Sorry to waste this much energy, brain space and computer data to extremely strict standards for old tech then to completely change the rules this far in is unexceptable... As you said there are other engine that came from the factory that dont suck oil, and im sure with there orginal cam plate so i dont think making a new MODIFIED cam plate There were alot of good suggested modifications that would have fixed your problem and were shot down that could have saved us this long and arduous soap oprea Sorry...do not pass go and collect $200, back to the starting box. Prop

Prop and the Blackhole Midget

Lawrence, So where can you buy steel backed white metal plate? http://www.jelbearings.co.uk http://www.jhrichards.co.uk/what-we-do/4527362886 Malc

Malc Gilliver

Prop has a point you know! If you are going to start modifying just block the breather and fit one to the rocker cover and be done with it... Been there done that and now oil smoke... But then it is not original:-) Cheers Tim PS have been enjoying the thread and have been a timing chain denier in the past!

T Dafforn

I disagree. The difference is that earlier suggested modifications such as changing the breather system, or drilling the front bearing cap drain holes (that I suggested) were means of resolving the symptom, not resolving the cause. If the cause of the problem is down to inadequate design standards of the cam retaining plate, then correcting that is a justified and proper solution. Of course we still need Lawrence to conduct further experiments to demonstrate - mainly to himself - that this is the root cause of the problem.

Guy W

Not really Tim, Lawrence is trying to identity the original torque figures, and maybe if we had the original drawings with the original flatness tolerances we could identify if the parts available are inside the original tolerances. Knowing BMC/BL they probably had a bloke at the end of the line smacking the cam plate with a mallet before sending the engines out. Malc

Malc Gilliver

Excellent Malc. I'll call them tomorrow, although unless I can buy a raw bit of plate, rather than get them to make it, I reckon it'll be too expensive. Prop. The factory presumably did the nuts to the correct torque, which we don't appear to know. However, as Dave has confirmed, the LATER dated Metro says 8lbft. Now since people rebuilding these are unlikely, like me, to have looked in the Metro manual, and are likely to have used 'experience', and done the bolts up to what we thought appropriate, we probably did them way too tight. So it's not a modification at all, if we simply do them to the correct tightness. And then to PREVENT it happening again, the added strength of a backing washer, seems entirely correct to me. It DOES fix the original problem, and DOESN'T alter the PCV system in anyway. Guy. How? How is the camshaft going to hammer against the obscured area that is deformed. At MOST the camshaft can only move a few thou back and forth. Can you imagine the force required, and against where? The only contact area is the bearing surface exposed to the front face of the camshaft. That too would be 'splayed out', but it's not. No it's pretty clear. The bolts deform the area. Why those marks? HEAT. Heat from the hot engine plate. And where the engine plate hasn't been in contact? NO HEAT MARKS. Yes indeed. When you come to undo the bolts, they seem quite loose. That's to be expected. Since at first they are over tight. Then the heat of the engine plate works to FURTHER deform and thin the ends. AND. You're forgetting something else. There is NO time for the camshaft to hammer away to create the problem. NUMEROUS, people (including me) have reported having this sucking problem -- AS SOON AS THEY RUN THE ENGINE AFTER A REBUILD. I think it's clear. The initial fitting of the endplate deforms it. Look at these pictures. The endplate has been forced AGAINST the engine plate, as evidenced by the flow of white metal INTO the bolt hole. NOT away from the engine plate, which is the only way the camshaft could hammer it, if it was even possible. Tim. Please show us a picture of your PCV setup.

Lawrence Slater

I did say that initial tightening of the bolts deforms it - and no doubt this results in an excess of oil flow through the resulting gaps. It probably comes as a surprise, but l am agreeing with you on that bit! It is the deformation of the white metal on the "ears" that looks to me more like the result of a hammer action. The cam gets a hefty fore and after hammering at every rev change from the dizzy drive gear. This won't deform the steel of the camshaft or the backing steel of the cam plate, but would be transmitted to deform the much softer white metal.

Guy W

Fair comments... Definitely reasonable to be trying to relieve the symptoms... PCV system not complex... rocker cover drilled and hose fitting added.. Pipe from hose fitting to port on single HIF44.. Lawrence i think we discussed it eons ago in another thread.. I know there was some concern about reversing the normal PCV flow.. but so far doesn't seem to dragging excess oil into the rocker area and runs pretty well. But as you say it doesn't solve the issue. My smoke blowing occurred on a home rebuilt engine with new cam and cam cover plate.. but cam bearings were not changed in the rebuild (perhaps a mistake).. Cheers tim PS sorry no pictures am away from home

T Dafforn

If this plate was designed today, it would probably have 'compression limiters' fitted. Imagine the cam plate with precision ground washers on the white metal side, to exactly the same thickness as the white metal. These would prevent the bolts squeezing the white metal out. Malc PS Found some more white metal companies - one is in Croydon. http://www.classiccarwebsite.com/white-metal-bearing http://www.rrbearings.co.uk/Pages/default.aspx These guys might actually sell you the white metal so you can make your own. http://uk.emrgroup.com//solder.php

Malc Gilliver

If there is sufficient clearance why not just ensure two cam plates are flat and bolt as a doubled up plate - using c/s machine screws if necessary. The additional thickness will greatly increase the stiffness and therefore reduce bending between centres. R.

richard boobier

Richard's idea seems an easy solution. Or make up the ring plate to give additional support, as suggested by Fergus. Seems a lot less problematic than getting a special one-off white metalled plate made up.

Graeme Williams

I've got pewter, technically these days Britannia metal, which is 92-6-2 so very close to some white metal compositions. 92-6-2 is 92% tin, 6% antimony, and 2% copper. I also have some casting alloy which is higher in antimony as it gives better definition as antimony expands when it solidifies. Copper could be added for extra hardness and will dissolve in the molten alloy like sugar in tea. I could provide some if you want to experiment. The alloy is extremely ductile and if you coat the steel then it might benefit from rolling to thickness, I have rolls but they're staying here, otherwise it would have to be machined, maybe with a fly cutter for a good finish. If I was making a new thrust plate I would likely choose bronze plate as fairly readily available and easy to machine and good for bearings. As regards a stiffer plate you need to look at Young's Modulus so you're not likely to find a replacement stiffer material of the same thickness easily/cheaply. Bronze is about 1/2 the stiffness of steel but then what thickness is the steel in the thrust plate compared to the thrust plate thickness, if the white metal is thick enough (steel thin enough) then maybe a bronze plate would be of equal stiffness.

David Billington

Lawrence The book I have is a 1970;s workshop book ,the cover is missing in action so I can't get an exact date but in the section Chapter 2 part A Engine in car repair procedures it lists - """""""" How to use this Chapter 1 This part of Chapter 2, describes those repair procedures that can reasonably be carried out on the engine while it remains in the car. If the engine has been removed from the car, and is being dismantled as described in Part B, any preliminary dismantling procedures can be ignored. 2 Note that, while it may be possible physically to overhaul items such as the piston/connecting rod assemblies while the engine is in the car, such tasks are not normally carried out as separate operations. Usually, several additional procedures (not to mention the cleaning of components and of oilways) have to be carried out. For this reason, all such tasks are classed as major overhaul procedures, and are described in Part B of this Chapter. 3 Part B describes the removal of the engine/transmission from the vehicle, and the full overhaul procedures that can then be carried out. Engine description 4 The engine is of four cylinder, in-line, overhead valve type mounted transversely at the front of the car and fitted over the gearbox. A low compression version is available for fleet use. 5 The crankshaft is of three bearing type, and the centre main bearing incorporates thrustwashers to control crankshaft endfloat. A torsional damper is fitted. 6 The camshaft is chain driven from the crankshaft and is supported in three bearings. The timing chain tensioner is of spring plate and bonded rubber type. The valves are operated from the camshaft by pushrod and rocker arm. 7 The oil pump is driven from the rear (flywheel) end of the camshaft, and a skew gear on the camshaft drives the distributor by way of a driveshaft. 8 The main design differences between the 998 cc and 1275 cc engines are as follows: a) The 998 cc engine has side covers which can be removed to remove the tappets whereas the 1275 cc engine has no side covers; the tappets can only be removed from the crankcase (see illustrations) . b) The 998 cc engine has diagonally split big-end bearings and fully floating gudgeon pins. Whereas the 1275 cc engine has cross split big-end bearings and gudgeon pins which are an interference fit in the connecting rods. 9 The engine has been designated the “A Plus” since it is an improved version of the “A-Series” engine fitted to Mini models. The improvements include a toughened crankshaft, a crankshaft torsional damper, and hard wearing exhaust valves and seatings. A fully closed crankcase ventilation system is employed, and piston blow-by gases are drawn into the inlet manifold through oil separators and a port on the carburettor. Torque wrench settings lbf ft Nm Brake servo pipe banjo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 51 Camshaft locating plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 11 Camshaft nut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 89 Connecting rod big-end - bolts . . . . . . . . . . """ AND ON AND ON AND ON So that would be 8 ft/lb or 11Nm then from my reading Also I wonder if people are getting mixed up with the torque specs for the timing cover which are listed at two different specs for the two different sized bolts there being 1/4 - 5/16 with different specs which I won'twrite here so it can't get twisted round Yes there is a problem with the distortion of the cam plate that needs fixing but I do tend to agree with Prop that this whole project was to rectify a fault without modifications and the non standard part of your engine I would consider at this stage is the duplex chain/sprockets taking up all available space in the cover With a single chain (std) there would bw a lot more room in there and the oil would possibly have more of a chance to settle. Maybee this problem has been introduced by the fitting of non standard part Do ALL the oil suckers have double row chains fitted My head is getting sore Cheers willy

William Revit

I don't think you could stiffen the cam retaining plate by simply using 2, stacked. The whole point is that it is sandwiched between the face of the cam front journal and the rear boss of the sprocket, tightened up against the stepped camshaft. This gives the end float for the camshaft. The only way this could be done is if the outer plate was machined with a larger internal bore as with Fergus' washer plate design, to clear the boss on the back of the sprocket. If this were done using a standard 3 eared cam plate the narrow bits would be even narrower and provide very little extra stiffening. Don't all 1275 engines use double row chains? I thought they were standard for 1275s. Or is it just the later models?

Guy W

Certainly all 1275 Spridgets had duplex chains. Possibly some A+ or transverse engines didn't. Cooper S and at least the early 1275GT Minis did.

Dave O'Neill 2

Correction to all who think otherwise. The whole point of this, and ALL the other threads, in which I HAVE PARTICIPATED, is to identify and to rectify the cause of oil sucking on 1275 Spridget engines, with properly connected PCV systems. So anybody may agree with anybody else, but I'm clear about what I've been doing, WHY I've been doing it, AND what I'm going to do about it. Everybody who doesn't agree with me is entirely at liberty to do so, and completely ignore everything I've done or said, and invent any means at all of dealing with any problem they consider their engine to have. Tim. Unless you have an air inlet on the timing cover, and if you still have an air inlet in the oil filler cap, whilst you will be relieving CC pressure, you won't be properly venting off the harmful contamination in your oil, properly. You will be pulling air in through the oil filler cap, and straight into the HIF, but you won't be properly extracting all the crap from the engine. You may well not have a rear scroll leak, and of course no oil sucking, but that's not enough. The PCV is there to protect the engine primarily. You may be saving the environment, but your engine won't be as well saved. Up to you, but I prefer a properly connected PCV system. Meanwhile, back to the point, --- again. Hi Guy. "The cam gets a hefty fore and after hammering at every rev change from the dizzy drive gear -- " Surely it doesn't. It's thrust forwards for most of the time. When the engine is cruising or decelerating, the thrust is less or reduced to almost zero. There would only be reverse thrust, and therefore any posiblity of "hammering" on the rear of the plate, if the engine was running BACKWARDS. Any contact between the nose of the sprocket and the rear of the cam endplate, is gentle and momentary. Otherwise there would be DEEP scoring on both. And BMC would have provided bearing surfaces to both. I thought about a double endplate, but I agree, it wouldn't solve the problem. It would just result in two crushed plates. As for the reinforcing plate -- that I suggested by see my crude sketch btw, as Guy just said, this maybe a mod, but it is part of identifying the problem, which may be a design fault. But if the correct torque is 8lbft, -- and to repeat once again for the umpteenth time --, I have exceeded that, AND re-used an already bent cam endplate, AND exceeded the 8lbts again, then the solution is to fit a new flat endplate, and use the CORRECT torque. No modification needed. BUT for belt and braces, I 'might' add a supporting plate to spread the clamping load to the centre spans of the cam endplate, to prevent it arching.

Lawrence Slater

Correction. I correct myself, and defer to Fergus. :). On the 29 February 2012 at 14:44:51 UK time, I wrote, -- "Fergus, how come you always get there first? lol. I was thinking along the same lines. If the plate was wider, it could perhaps be fixed at 3 additional locations, betewen the current "ears". That would prevent it arching, and allow for reduced bolt torque, since there would be 6 of them. However the engine plate on the side of the so called overflow hole is too thin. So your idea is far better. Is that the real thing? It looks as if you've just made one? What's it made from? "

Lawrence Slater

Clearly the next step is to reassemble with a fresh cam locking plate, checked for flatness before installation and properly fitted with bolts correctly torqued and not overtightened. All as factory, but then checked with feelers that the plate hasn't arched again. If this IS the root cause of the problem them this should stop the oil overfilling the TCC. The issue of how long this lasts, and therefore whether the plate or its fixing needs upgrading is really a separate step.

Guy W

I suppose I saw it machined from steel or possibly aluminium. I'd assume the thrust washers available today are to all intents and purposes reproductions of what was originally fitted, and as such may look similar but behave a little differently. A bit like dodgy rotor arms or front wheel bearings.Certainly all or most of the thrust plates I've seen that came off original engines seem to have 'even' wear patterns - it seems to be the later ones that show the arcing. Or maybe the guys on assembly did just thump them flat with a copper mallet.

Fergus Pollock

Correction to my correction. ;). Hope you don't mind Fergus. :). Fergus suggested a new cam endplate, better designed and stronger than the original. I then suggested, -- "How about reinforcing the existing one?" 29 February 2012 at 16:29:17 UK time. Just for the historical record you understand. LOL. Guy. Bang on the money. And if that does indeed fix it, then I believe it WILL last. The evidence being, that from my own personal experience, and that reported by others, it's only when the engines have been rebuilt, that the sucking starts. The factory did it right, and we f*cked it up. lol. As regards satisfying myself that this really is the problem, no matter how well a theory seems to hold water, it's not until it's put into practice, that it REALLY holds water (oil), or leaks. :). Cold today, and I'm not looking forward to ar*eing about in my garage. But hey ho. PS. Would white metal, be the only suitable bearing material here?

Lawrence Slater

Lawrence Hope I didn't upset you I'm batting for Team Slater here Just trying to think of out of the box possibilities I understand 100% what you are trying to get to the bottom of I just wish I could help more cheers willy

William Revit

No worries Willy. I love to get out of my pram once in a while. LOL. And you DID help, with that tale of the old fella and the two types of cam bearing. Mine had to be the wrong one. Cheers.

Lawrence Slater

AND NOW. WITHOUT FURTHER DELAY THE MOMENT YOU HAVE ALL BEEN WAITING FOR. I can say, much as Inspector Clouseau would have said. ================ "THE CASE IS SOL-VED." ============= It was the bent cam plate wot done it gov. And if you'll indulge me, and not interupt, I'll show you, in a few 'hopefully' contigous posts.

Lawrence Slater

For those of you following the plot, my proposal is that the camshaft retaining plate is bent. Deformed because it has been overtightened, causing it to 'arch' between the fixing bolts. This allows a continuous flow of oil via the front camshaft journal/bearing, into the TCC, when in fact it should only be a 'pulse' of oil, once per revolution of the camshaft. In order to demonstrate that, without risking a new camshaft in the process, I decided to prove the leak, rather than fix it. To that end, I blocked up the feed hole in the retaining plate with plumbers solder. I then fitted the plate and ran the engine. As I predicted, even with the oil feed hole blocked completely, there was still a constant supply of oil to the TCC, and it wasn't too long before the TCC was once again awash with the stuff, --- BUT CRUCIALLY, NOTICEABLY LESS SO THAN BEFORE I BLOCKED THE FEED HOLE. So here are the first pictures. And if you'll continue to indulge me, and not interupt, I'll show you, in a few more 'hopefully' contiguous posts. I thank you. lol. :).

Lawrence Slater

And here it is again, soldered and clamped to my spare engine front plate. I've shown the 6thou" gap on one side to better illustrate the oil leak potential. You might like the video too, showing how loose the 6 thou" blade is. http://tinyurl.com/peuo3lh A moment please, while I prepare the next installment. :).

Lawrence Slater

Here it is, bolted back on to my running engine again. You just wouldn't notice there's even a gap under the edges would you. Unless you used a feeler blade, you'd never know. And why would you? It looks fine, -- until you look REALLY closely. But back in the early 1980's circa 82/3, it never occured to me. And so, to how tight did I do it up, THIS TIME? First I used a short ring spanner. I turned the screws until it felt good and tight, until I wouldn't want to go much more. That feeling that metal is well and truly held flat against metal and there's no give. I tested it with my 0-60lbft T/wrench, -- BARELY 4 lbft on my dial. So I went to 5. With the wrench it felt like nothing at all. With my spanner it now felt even tighter. So I went to circa 8lbft on my dial. Zero effort with my T/wrench. Now it felt like it would strip, with the short spanner. So I went to 10lbft. again, ZERO effort with a T/wrench. No way would I have gone so far with a spanner. So. Maybe there's a reason that NO TORQUE figure was quoted originally. You're NOT supposed to torque those screws? And IF you do, then use a SMALL T/wrench, with an ACCURATE reading at 8lbft. I have NO IDEA if my 0-60 wrench, is even close to accurate at 8lbft. I've DEFINITELY been overtightening those screws, and THAT'S what deformed the camshaft endplate, and THAT'S what lets too much oil into the TCC A moment more please :). Bear with me for the next bit.

Lawrence Slater

And finally. Here's a still from the video with the engine running with the soldered camshaft endplate. Here's the link. http://tinyurl.com/lhgomgz This clip starts about 3 mins after starting the engine. It was STONE cold in the garage today. Bloody taters. So the oil took a while to flow. But there was evidence of splashing almost immediately -- proving the leaking endplate. Unfortunately condensation obscured it a bit, but as it approaches 50 seconds, you'll see plenty of oil start to appear. At the end, you'll see the canister breather pipe again. Once again it's loaded with oil. BUT THIS TIME, REMOVING AND REPLACING THE OIL FILLER CAP, controls the oil a lot more. There's still too much oil, but because there is less oil, it's more controllable. And keep in mind that this is the modified TCC. The breather canister is being filled with oil being thrown directly at the entrance by the timing chain, -- even though there is a baffle. With the correct canister mounted on the face of the TCC, there would be even less oil in the breather tube. But the main point here is, that if ALL the gaps under the camshaft endplate are closed, and ONLY the designed oil feed hole supplies oil to the timing chain, then there WON'T BE ANY OIL IN THE BREATHER TUBE, other than the mists and vapours that are meant to be sucked up. Fitting a FLAT camshaft endplate, and NOT overtightening the screws, SOLVES THE PROBLEM OF OIL BEING SUCKED UP THE ENGINE'S BREATHER. For my next trick, I intend to prove that by REPAIRING my bent plate. I'll remove the solder from the feed hole, flatten it, pad the crushed bolt hole locations, screw to the engine, and show the correct amount of oil in the TCC. --- HOPEFULLY. LOL. :) Please feel free to resume the conversation. :).

Lawrence Slater

For your next trick how about sorting FWB out

mark 1500 on the road Preston Lancs

That's been done. Anything else? ;).

Lawrence Slater

So would a coat of blue holamer gasket stuff under the cam plate fix the issue and not have to replace the cam plate

Prop and the Blackhole Midget

Excellent work Lawrence well done. Mine didn't suck oil anymore because I controlled the air flow by fitting a new cap! Despite using the old camplate when I renewed the camshaft the reduced cam end float tolerances have ensured I have reasonable levels of oil in the TCC and by luck mine wasn't deformed enough so it works as originally designed. A 30 odd year old mystery pretty much solved!

Bob Beaumont

I'm rethinking what we discussed before about the amount of oil that should actually be in there. I'm not sure it was only the cold that delayed the 'flood curtain' today. I think it was the reduced flow with the feed hole blocked off. The oil thinned, and then it flooded, presumabley as it was suddenly thin enough for the flow to increase from the leaks under the endplate. Meanwhile, before any oil ran down from the top, there was already splashing. Obviously there couldn't have been a reservior at the bottom, because I had only just refitted the cover. I think the initial splashes of oil came from the front main bearing. And if that's the case, I think that the oil feed from the camshaft, may only be to lube the camshaft sprocket nose, against the rear of the camshaft endplate. Leaving the main bearing to do the job of supplying the oil for lubing the chain, with the unwanted amount simply draining away via the two holes in the main cap. I've forgotten who said that first. But someone did back in 2012.

Lawrence Slater

From: Prop and the Blackhole Midget Missouri USA on 19 January 2015 at 20:54:25 (UK time) So would a coat of blue holamer gasket stuff under the cam plate fix the issue and not have to replace the cam plate Prop, When I had a go at my timing cover I applied blue hylomar to the back of the cam plate and I did get no oil sucking, and I can't really state that the hylomar fixed it as other stuff might have helped - ultimately the oil suck returned some time later, so blue hylomar doesn't work. However ......... maybe JB weld might ?? Malc

Malc Gilliver

I'm looking at doing exactly that today Malc/Prop. And, I think that JB Weld is going to work, where I think hylomar and the like is too soft. The pressure might well blow it away, depending on the gap size to be filled. However, it's not quite so 'simple'. Firstly, you have to be VERY careful not to get any sealant on that part of the camshaft endplate in contact with the thrust face of the camshaft. So, I'm going to experiment with a thin gasket instead. Secondly, in adding jb weld/whatever, to the surfaces between the plates, you move the camshaft forwards by "x" thou inches amount. This will have to be compensated for by adjusting the shims on the crankshaft nose -- by adding the same amount --, or by grinding the same amount OFF the camshaft sprocket nose, to allow it to sit in the correct position and restore the alignment with the crankshaft sprocket. But, that STILL MAY NOT fix the problem. Remember what Fergus found on that Minfinity site? === ==== "If you are using a new thrust plate they are usually not flat meaning that the apparent installed thicknes is greater meaning less clearance." Add to that, if the camshaft endplate ISN'T flat as mentioned above, and bolting it up exacerbates that, then not only is the endfloat in question, but oil will still leak past the oil feed hole. It won't leak between the endplate and the engine plate, because you've sealed it. BUT IT WILL STILL LEAK, because the camshaft thrust face isn't in contact with the retaining plate all the way around. So first job is to ensure the new endplate plate IS flat. Next job is to ensure that the engine plate has no protrusion at the bolt holes that might distort the new endplate as it's bolted down. It's also worth holding a straight edge against the engine plate, to see how much if any recession there is, caused by errosion from the hot oil, leaking over it under pressure. Mine IS erroded. See my picture below, posted 17 January 2015 at 12:12:39 UK time

Lawrence Slater

Phew!. There's a bit of luck. I guess nobody's reading this, so nobody spotted my deliberate mistake. ;). "by grinding the same amount OFF the camshaft sprocket nose, --- " ----- That wouldn't be a good idea, to move the cam sprocket back into line, because it would reduce the endfloat, which might be a good idea. So better to shim the crank sprocket. :). Meanwhile, here's a picture of how I 'flattened' the slightly bent camshaft endplate. Actually I've put a reversed bend in it. Trial fitting it to my spare engine plate and bolting it up, results in the camshaft plate being pulled flat against the engine plate at all points; -- With the exception that my spare engine plate, just like the one on the Sprite engine, has reccesed areas between the bolt holes. Hence the gasket, in the next post.

Lawrence Slater

I used red hermetite. I'll start it up tomorrow, and see if it works.

Lawrence Slater

Interesting and impressive. but this level of care and attention to detail suggests to me that if normal quick but careful assembly still results in some oil leakage, then this should be acceptable and not alone result in oil sucking. Either your cam plate leakage on all 3 engines was at the extreme end of the scale, or some additional factor is still involved. There is of course one factor common to all 3 engines!

Guy W

To be fair, there is another conclusion already touched on. And that is that the cam plates currently available are soft whimpish affairs that bend and leak at the slightest provocation. And that the originals were just better items that could be quickly assembled without fear of leakage.

Guy W

"There is of course one factor common to all 3 engines! " And before bob posted his thread, I hadn't bothered to search the archives. So wihout Bob's symptoms, I was indeed prepared to accept that it was only my TWO engines -- as was the case then -- , and that it must be something I'm doing or not doing. Then comes Bob, then the discovery of all the other threads, subsequent reports in new threads, and finally I buy a Midget, I do nothing to the engine myself, except change the oil in the winter, and bingo, it sucks oil. So at least one thing has been illiminated for certain. ME. So that's something at least lol. -- Unless of course everybody else makes the same errors I make, whatever they are. As for "some leakage". I agree. I think the sucking depends on the degree of oil in the TCC, and that depends on the level of oil leakage. As a matter of course, as the endfloat increases with wear in the endplate, so must the oil leakage past the endplate. But I think it's the extra leakage under the sides of the plate, that causes the real problem. And if a used endplate is put back on, and again overtightened it must make it worse, leading to errosion of the engine plate too. Mine probably are at the extreme, and because I re-used the endplates, that is down to me. I had another thought today, not really so different to what you just said Guy. What if the endplate 'warps' when it gets hot? It's a laminate of 2 different metals. Could this cause it to arch as the 2 metals expand at a different rate? Could it be that the originals, or better quality replacements, are made of suitable stuff, and the ones that bend and arch aren't? It certainly wasn't difficult to bend the one in the previous pictures back to shape.

Lawrence Slater

I'm not sure I'd want to use Hermetite inside an engine. This is what it looks like under 2bar (28psi) of steam pressure!

Dave O'Neill 2

400 posts!

Dave O'Neill 2

Lawrence, my 'common factor in all 3 engines' was a jest, as l sure you realised;-) At least you understood what l was implying! What is interesting is that the cam retaining plate doesn't appear to have been modified or improved on during the evolution of the A series. Despite the other changes that have taken place like the CCT breather system and the higher capacity oil pump. It appears that development was taking place that inadvertantly brought the cam retaining plate to become a marginal design which worked OK from factory but had the potential to become a weak link in the system under certain conditions.

Guy W

Lawrence, Did you drift the cam bearing back to flush? Is there an issue with the gasket allowing too much cam end float? Are you still in the testing phase and intend to eventually get a new cam plate or, if this works, is it the final fix? I admire your perseverance. Charley

C R Huff

Dave. It's all I had to hand. If it works for a hundred or even 20 miles, I'll be happy. The bottom end of the engine needs rebuilding anyway. Slightly noisey big ends. But anyway, I wonder how much psi there can be at the cam plate anyway? How much is left from the front main I wonder? I'll know soon enough. If it looks good through the window, I'll hang the valance and wings on it and go for a drive, -- on a dry day, as I haven't got a roof on it. -- Only 400? Seems like 4000. lol Yup I know you were Guy, but there's quite possibly some truth in it. Has anyone got a late A+ engine that they could pull apart to look at the cam endplate? As you say Guy, it doesn't seem to have changed at all. Hi Charley. Since that earlier picture of the front cam bearing was taken back in the early 80's, I must have either had the bearing replaced, or it's been moved forwards, because I can see that it's almost flush with the front now. I think it must have been replaced, as otherwise the holes wouldn''t have lined up. But it was a long time ago. When I strip it, I'll know for sure. The gasket behind the cam endplate won't increase the endfloat. All it does is move the camshaft, endplate, and camshaft sprocket assembley, forward by the thickness of the compressed gasket. The whole lot just bolts to the front of the engine plate. 'IF' this works, if it doesn't spring a leak, then this will be the final proof, and I'll use a NEW cam endplate when I re-build my spare engine. But I'll do the gasket routine on the Midget just to be sure. If it fixes both, then it's new cam endplates all round. lol. Not knowing the cause has bugged me for over 30 f*cking years. :). On the other hand, it's not really much bother, and for all the time I had the HIF fitted to the Sprite, until I changed the oil in the cold weather instead of the summer, it didn't even suck oil. It's all madness really. I'm sure I could find something more productive to do, if I really tried, LOL.

Lawrence Slater

I rebuilt an A Plus for the A35 about 3 years ago. The cam plate was no different,and as I recall I checked its flatness on glass no surface dressing was needed. It was assenbled with Wellseal. For what it's worth I've never heard of the later engine sucking oil but interestingly these engines dropped the duplex in favour of a single row timing chain with tensioner.

Fergus Pollock

Hi Fergus. And they still used the TCC breather, as you've already shown with pictures, which also show the full shroud around the entrance to the breather canister. Maybe they knew something that they never told the public?

Lawrence Slater

Hi Fergus. I got this from somerford mini's website. They show that the A+ TCC was used with an HIF(less suction), and an additional breather canister. So in addition to going back to a single chain, it was also with split, and reduced suction. Is this significant I wonder. And for confirmation purposes. 'Oil pressure'. I've confirmed the oil gallery oil pressure is NOT too high in my engines. Not only is the pressure relief valve working and free, but my oil pressure gauge is reading too hign. My engine is running at normal oil pressures. I considerd that oil pressure was elliminated as a cause anyway, because others who also have oil sucking reported normal oil presssure. But see next post. :(.

Lawrence Slater

Bugger again. Keep forgetting picture upload. Hi Fergus. I got this from somerford mini's website. They show that the A+ TCC was used with an HIF(less suction), and an additional breather canister. So in addition to going back to a single chain, it was also with split, and reduced suction. Is this significant I wonder. And for confirmation purposes. 'Oil pressure'. I've confirmed the oil gallery oil pressure is NOT too high in my engines. Not only is the pressure relief valve working and free, but my oil pressure gauge is reading too hign. My engine is running at normal oil pressures. I considerd that oil pressure was elliminated as a cause anyway, because others who also have oil sucking reported normal oil presssure. But see next post. :(.

Lawrence Slater

"I was all right for awhile I could smile for awhile -- " http://www.youtube.com/watch?v=pra6ezRMejg I'm going to need a bigger window. :(. Before fully assembling, starting the engine, I checked that the camshaft endplate gasket i'd made, and the red hermetite was nicely fixed. I couldn't get a feeler blade under the plate anywhere. I checked the endfloat with a blade under the nose of the sprocket once I'd fitted it. Circa 3 thou". I put the TCC back on, lowered the engine, filled that radiator. I sealed the modified breather canister, and refitted my clear pipe sight tube. I left the sight tube open, so there was NO SUCTION on the TCC. Very cold in the garage. I started the engine. I left the engine running at 2500rpm for some 15 minutes, whilst I stared at my window and sight tube. During that time, at first I was getting concerned that I couldn't see ANY OIL at all. All I could see was the clean camshaft sprocket revolving. Had I blocked the oil feed with the gasket or the red stuff? So I opened the oil filler cap and shone a torch in. Oil flowing nicely along the bed of the top of the cylinder head, so at least it was reaching beyond the camshaft that far. I switched the fan off to let the water get hotter, and switched it on again at 160f. At around 5/6 minutes, I saw some splashes of oil on the window, and a small stream begin to run down the inside of the window from the top. The sight tube was still completely empty, as it had to be, without any oil at that level in the TCC. The splashing increased, and the flow from stream increased a little too, and then remained stable. I relaxed. Here's a picture at that point. ---- I was all right for awhile I could smile for awhile -- . AND THEN. At about 10 minutes, with the water temperature reading about 170f, ------- WITHIN A FEW SECONDS, THE OIL SUDDENLY FILLED THE WINDOW. IT ROSE TO THE TOP OF THE TCC, AS SHOWN BY THE SUDDEN FILLING OF THE PREVIOUSLY COMPLETELY EMPTY SIGHT TUBE, TO THE SAME LEVEL AS THE TOP OF THE TCC ----. There was NO suction from the PCV, and the rocker cover oil filler cap was OFF, so little CC pressure either. THE OIL FLOW INTO THE TCC, HAD WITHIN A FEW SECONDS INCREASED SUFFICIENTLY TO REACH THE TOP OF THE TCC. It's my guess that if the normal TCC with it's breather canister had been on there, and connected to the PCV, it would have sucked oil. What happened? I figured that as Dave predicted, the red hermetite/gasket, gave way, and oil was pushed out by the pressure behind the camshaft endplate. I continued to watch and at about 15 mins, i switched off and let the oil drain down. I started it again, the oil soon filled the window again, but remained below the top of the TCC, judging by the now empty sight tube. Crying over you.!!!!

Lawrence Slater

I stripped the TCC off again, hoping to see a blown gasket. But even after a double check with feeler gauges, there was NO GAP UNDER ENDPLATE. The gasket held. So where did all that extra oil come from to suddenly fill the TCC? Why does it run for 10 minutes with minimal oil in the TCC, and then suddenly fill up? It took longer to fill the TCC this time, but was this the result of sealing the cam endplate to the engine plate, or just simply the VERY cold oil at start up time? If not from UNDER the endplate, and not from the oil feed hole, that only leaves the centre thrust face of the camshaft journal, -- (which should be minimal else why have an oil feed hole in the cam endplate anyway?) --- , or the front main bearing journal. But why should that suddenly increase leakage? Is there a sudden oil pressure surge? NOT according to my oil pressure gauge, which I now know is reading high anyway. And if the front main bearing suddenly sprung a leak, it would result in an oil pressure drop, which I've not seen. That only leaves 2 possibilities, -- that "I" can think off. A sudden blockage/restriction of the oil feed to the rockers -- no evidence of this judging by the oil in the rocker cover, or the poor contact between the camshaft thrust face and the cam endplate.

Lawrence Slater

Now I'm almost at the "give it up" point. But you know what they say. Rome wasn't built in a day, and -- Spridgets are a pile of crap built in 5 mins on a Friday afternoon. lol. Here's a picture of the endplate as it came from the engine and as it is now with balc marker ink applied to it. Although it was used, I thought I'd made it flat. It was flat enough to seal against the engine plate, but I can only assume that in bolting it up again, nothing like as tight as I've done before, it was still distorted. You can see that the camshaft still didn't make contact with it all the way around. Is this how the extra oil got in there to fill the TCC? I so, why suddenly after 10 minutes? Why not before? I'm guessing, but maybe the oil is simply too thick before, and suddenly reaches a hot enough temperature, to thin sufficiently, and to be squeezed through the centre in a much greater quantity. And as there is no continuous contact, it would also be flowing thrpugh the oil delivery hole, irrespective of the oil slot in the camshaft being in alignment with it. I might also have exacerbated it with the use of a gasket. It's about 15 thou". This has pulled the camshaft out of the bearing by about the same amount. Maybe that increased bare journal allowed more oil into the system. But again, why did it take 10 mins for the sudden increase? Temperature again? If the camshaft endplate isn't the cause of the sudden increase of oil, then what is? I've checked the clearance on the front main journal/bearing, and I 'CAN'T' get a 2thou" feeler in between them. And it has to be remembered that oil sucking happens to newly rebuilt engines. So now I'm going to bolt the plate onto the engine again. Spin it on the battery, take it off, and see where the black marker ink has been in contact. I'm running out of ideas. Apart from "give up", any 'sensible' suggestions? Edit. How about a leaking front engine plate gasket?: -- camshaft to CC pressure relief hole area? If that leaked, that would supply some oil. I'll take a look. I suppose I might as well, I've looked at everything else!.

Lawrence Slater

Lawrence, I have been wondering about the effect of using the end plate that has already been worn in three spots. If worn far enough, I suppose it would make full contact again, but by flatting it, you stopped that process and probably made the non-contact area greater. Is that enough to do it? Maybe not, but it could be a contributor. You mention that the gasket pulls the cam proud of the cam bearing (if I understand the directions of movement correctly). If you run the cam either proud of or recessed into the cam bearing, haven't you defeated the "shut off" valve effect and thus allowed it to run oil out of the hole all the time? I think it will be hard to prove anything until you have a flat cam plate in good condition, and additionally have the cam, cam bearing, and engine plate all flush with each other. Charley

C R Huff

Sort of echoing Charley here, but for me I think you have enough evidence to do two things. One, check the post about having the "right' camshaft bearings. (see Willy's post 18th Jan) Two, buy a new end plate, make sure it's flat and fit that. Did you have a paper gasket under the end plate, or just hermatite ? I've mentioned this before, but I still wonder about the oil filter pressure safety valve - I need to find one and understand how it works, because the surge came from somewhere and I can't think of anything else. Malc BTW, it's Five o'clock where you are, have a beer !!

Malc Gilliver

Hi Charley, The gasket under the camshaft endplate, on top of the engine plate, moves the whole lot forward by the thickness of the gakset. Hence it moves the camshaft forward, out of the bearing, by the same thickness. As long as the thrust face of the camshaft is in contact with the endplate the oil feed hole will only be 'open' once per revolution. -- BUT; As you say, it's still not flat. The gasket stopped the leak under the cam endplate, but I'm guess it's still leaking through the centre, where there is no contact between the camshaft and the endplate. So I need to attend to that. I don't want to use a new plate until I can be sure I won't immediately bend it again. Malc. This can't be a surge from the oil filter. If the oil filter was holding back the oil, the engine would have been starved of oil everytime it was started up, and been knackered long ago. Whatever happens, happens downstream of the oil filter.

Lawrence Slater

Lawrence, Correct me if I am wrong, but doesn't the hole in the cam plate extend out past the face of the cam? If so, then if the cam plate is held out by 0.015" from the engine end plate and the end of the cam bearing, you have created a 0.015" annulus which is constantly fed with oil. So, even when the plate and cam face are in contact, oil is still delivered radially into that annulus by the slot cut in the cam end. Then, that oil is free to be forced out of the hole in the cam plate because the hole is not entirely covered by the cam. The cam/cam plate contact only serves to reduce the size of the hole rather than blocking it. I don't have the parts in front of me so I may not be visualizing it correctly, but it's worth a thought. If you think I might be right, here is a thought on how to test it. Get the engine well warmed up like it was at the 10-minute mark when it flooded, and maybe beyond so it doesn't cool below that point during the test. Then pull the TCC and the spark plugs, and crank the engine with the starter to see if oil comes out the hole constantly or in pulses. I am thinking that on cranking there is enough oil pressure & volume for this test to work. This assumes that you can see it with the cam wheels and chain in the way. Charley

C R Huff

Hi Charley. Yes, If I understand you correctly, there is a chamber. You're right, looking closer, the oil feed hole in the camshaft endplate, is ALWAYS open to the oil circulating around the exposed end of the camshaft. So if there's too much diametrical clearance in the camshaft bearing, there could be a 'flood' from there. fitting a gasket creates a bigger chamber. So maybe I did indeed make it worse than it would have been. "The cam/cam plate contact only serves to reduce the size of the hole rather than blocking it." That's true, but when the 2 align the tap is exposed to the slot and the full flow of the oil for a 'moment'. " --- pull the TCC and the spark plugs, and crank the engine with the starter to see if oil comes out the hole constantly or in pulses. --- " To do that, I have to drain the radiator, remove the bottom hose from the water pump, undo the engine mounts, lift the engine, pull the crank pulley and then pull the TCC. And then you still can't see anything because the cam endplate is hidden behind the sprocket, and because it's so cold, the engine/oil cools very quickly too. But in principle I agree, and was already going to repeat a better version of a test I did on my spare engine in 2012. Then I only had the crank in and a sump full of oil, with no head. I spun the crank and the camshaft by hand. This time I'll remove the rockers and the plugs, and spin the crank, and then just the camshaft by the same means, and see where the oil comes out. BUT, see my next post, for a NEW(old) discovery.

Lawrence Slater

And guess what slipped into my subconcious, until my last but two posts? I forgot about the "joker in the pack". I just said, "Edit. How about a leaking front engine plate gasket?: -- camshaft to CC pressure relief hole area? If that leaked, that would supply some oil. I'll take a look. I suppose I might as well, I've looked at everything else!." Back on 24 February 2012 at 14:28:27 UK time I said, "Oil has been leaking from a faulty gasket, a poorly fitting camshaft end plate, too much camshaft end float, and above tolerance wear/damage in the front camshaft bearing/journal combination. These are the missing factors. With the gasket being the hidden joker in the pack.". --- "The engine front plate bolts to the engine block, and in between is a gasket. That gasket stops engine oil (from the timing cover) leaking to the outside via the rear of the front plate. HOWEVER. It ALSO stops oil under pressure, leaking into the timing cover. -------- But only if the gasket is in good condition. Mine isn’t, and oil has been escaping from behind the engine front plate directly into the timing cover." Bob said, "One thing i did change on the rebuild was the front engine plate! " By then we were talking about the flatness of the front face of the engine plate, and not the gasket behind it. TODAY. I slid a 4thou" feeler gauge BEHIND the engine plate, and it came out adjacent to the bottom cam plate fixing hole, in the space next to the camshaft front journal. Oil has been leaking from the journal behind the engine plate, creating a 2nd small reservoir of oil, which then emerges into the TCC. I knew I had a slight leak to the outside, but completely forgot the route to the TCC. With heat, does this gap enlarge? Or does the oil just become thin enough to flow faster? It's very obvious where the oil has been leaking from BEHIND the camshaft endplate, to BEHIND the engine plate, and through to the TCC. This is exacly how it looked when I pulled it off. The oil was already there. So now I'll fix the engine plate gasket before having another go with the camshaft endplate and anything else.

Lawrence Slater

Hmmm, That dosnt look good, I do not recall the front of the block looking like that....its like someone wedged in a chunk of missing metal on the front of the engine I hope im wrong... I just dont recall ever seeing the front of the engine looking like that Prop

Prop and the Blackhole Midget

So if the cam plate is overtightened sufficiently it would follow that this may have also resulted in the threads in the block being pulled up proud of the face. Pulled enough to prevent full gasket contact and enough to allow the 'thinned' oil to blow locally past the threads under the plate.

Fergus Pollock

Hi Fergus. " --- the threads in the block being pulled up proud of the face." That's EXACTLY what I found when I stripped my spare engine back in 2012. And, the threads on this engine are pulled up too. Not much, and mostly at the bottom cam endplate bolt. But it wouldn't take much. I can see that there is a very slight 'chamfer' on the reverse side of the engine plate around the cam endplate bolt holes, but to me they look too small to avoid the pulled threads completely. I'm wondering if instead of a deliberate chamfer, they are in fact an impresssion made by the proud threads in the block face. It's a pretty thin gasket too. My spare engine had a significantly thicker one if I remember that right. Here's a picture. Prop. All 1275 spridget blocks look essentially like that.

Lawrence Slater

Here's my spare engine from when I pulled off the engine plate back in 2012. Come on over baby, lotta leakin goin on ;).

Lawrence Slater

I think you found it now.I'd dress the surface of the block and chamfer the top of all the threaded holes. Ditto the engine plate. Degrease and then assemble with Wellseal on both sides of the gasket.

Fergus Pollock

It looks like the three bolts that hold the cam plate on also hold the front engine plate on. Keep that in mind when you consider reducing the torque on those three bolts. If you reduce the torque on the three cam bolts to less than the rest of the engine plate bolts, you may cause a leak at the engine plate / engine block interface. Charley

C R Huff

It's a bad design, don't you think? Removing the camshaft retaining plate, removes the compression on the engine plate gasket. If the engine plate isn't entirely flat, and or, is under any tension because it also serves to hold the engine on the chassis, then any oil around the camshaft journal will seep capillary like, behind the engine plate. Then you bolt it up again, with a potential for a future leak. On both my spare and current Sprite engine, I used sealant on the block face, but none on the engine plate. I can see that both leaked across the face of the gasket. On my spare engine, the one with the brown gasket below, when I removed the gasket it wasn't stuck around the camshaft very well on the side adjacent to the CC pressure relief hole, and I can remember seeing traces that it leaked behind as well. I haven't tested how well the current engine's gasket is stuck. I'll check. Yup, I'll do that Fergus. I've not used Welseal. Why/is, it superior to hylomar? Charley. Good point about the tightness of the bolts. Again daft design having the cam retaining plate bolts also hold the much heavier/thicker engine plate in place too. It wouldn't matter if there wasn't a gasket behind it, but there is. Haiving said that though, it has to be remembered that most engines don't suck oil. So as long as it's not overtightned in the first place, and if it is, proud threads are removed, a good well stuck gasket used, along with a flat camshaft retaining plate, then there's no problem. :). AND. All that only applies, IF I have now finally found ALL the possible reasons for the TCC to suddenly iverfill with oil.

Lawrence Slater

Wellseal is the stuff originally used on factory assembled engines and I've found it superior to Hylomar as it doesn't seem blow or wash out. Silicone is fantastic stuff too especially on gaskets subject to movement like half shafts, but near an oil gallery you need to take care and clean up all excess traces once it's bolted up. But to get good adhesion with any you'll need to degrease with cellulose thinners first. Looking at the block face it makes you wonder if the diameter of the cam retainer bolts couldn't have been increased to match the rest, resulting in common torque and even clamping. Over the years the 'A' Series block grew considerably in height so there was far more meat to play with on later engines. But I suppose the bottom line is if you assemble an engine as factory spec it's unlikely you'll see a problem.

Fergus Pollock

The torque on the three cam plate screws will always be less than the others, due to them being 1/4" UNF as opposed to 5/16". Also, each time you remove the timing cover, you are also removing four of the 5/16" screws that are clamping the front-plate.

Dave O'Neill 2

But the real limit on the torque of those 3 bolts, is the weakness of the camshaft retaining plate. That's why it's a potential problem.

Lawrence Slater

Here, according to at least one person, is some more "hogwash". Going back to the front camshaft bearing again. Willy talked about there being two different types. I pulled the old scored front bearing from my spare engine, and reduced the diameter so I can push it in and out for comparison. When fitting the front bearing, what exactly should it be lined up with? The oil feed hole FROM the crankshaft main bearing, or the oil feed hole TO the rockers? Here's the front and centre main oil feed holes to the camshaft bearings. The front is bigger, as it has to supply the TCC and the rockers as well as the camshaft bearing. Why make the front bearing hole bigger, if you then obscure some of it with the camshaft bearing? The next picture is interesting because it shows the bearing oil feed hole alignment, -- in two different positions.

Lawrence Slater

If the front camshaft bearing is fitted so that the oil feed TO the camshaft bearing is fully OPEN, then the camshaft bearing is too far back, and the oil feed to the rockers, is partially obscured. This is how someone fitted my bearings back in the 1980's. Next picture shows the bearing fitted flush with the block face, with the rocker oil feed fully open, but with the oil feed TO the camshaft from the main bearing, partially blocked. Why have a large feed oil hole from the crankchaft main bearing, if you then partly block it off with the camshaft bearing?

Lawrence Slater

This is how this camshaft bearing has to be fitted in order to keep the rocker oil feed fully clear.

Lawrence Slater

The bearing on the LEFT, is a new GLYCO solid ring type that I bought from MiniSpares. http://www.minispares.com/product/classic/AEC3063.aspx There's a big difference in the size of the oil feed hole to the rockers. The size of the oil feed hole in the block to the rockers, is 6mm. But the size of the rocker oil feed hole in the OLD bearing on the right, is 4.75mm. This means that when the bearing is installed, even if it's directly over the rocker oil feed hole, the oil feed to the rockers is restricted. Why have a large hole in the block, and then obscure it with the bearing? On the new minispares front bearing, the rocker oil feed hole is larger then the hole in the block. Have I got an OLD WRONG bearing? Does anyone have the drawing/specs for these bearings? Or does anyone have a GENUINE OLD SPRIDGET 1275 front camshaft bearing for measurement and comparison?

Lawrence Slater

Is the answer wrapped up in what Willy said about there being different bearings for the 1275 from the earlier 1098 & 948? Does it make any usefull difference for meeting the oil holes if you turn the bearing end for end before installing? Do Mini Spares or other vendors indicate different bearings for different blocks? I also would not expect the bearing to block part of the oil holes, and it seems it should be flush with the face and not overhang to the rear. Charley

C R Huff

Hi Charley ----- "different bearings for the 1275 from the earlier 1098 & 948?" ----- Yes there are. They have different part numbers. But according to minispares, the 1098 & 948 bearings will physically fit the 1275 blocks. And again according to them, it hasn't caused a problem, -- at least in Minis. Moss et al, also list different part numbers. BHM1210 for 1275's and BHM1211 for 1098/948. But if they BOTH physically go in, what's the difference between the two types? DOES ANYONE HAVE A SET OF 1098 BEARINGS FOR MEASURING THE POSITIONS OF THE OIL HOLES? ---- "if you turn the bearing end for end before installing? " ------ No you stil can't align BOTH holes. The slot becomes the feed to the rockers, and the hole becomes the feed FROM the crank main. But it doesn't help. I agree. I would expect the holes to align cleanly. Are the wrong bearings being fitted?

Lawrence Slater

CRANKSHAFT MAIN bearing clearance. The BMC book says, 0.0010" to 0.0027" Mine is 0.0025" on the relevant FRONT bearing. Anybody else here measured theirs? With or without an oil sucking problem.

Lawrence Slater

I've now got confirmation that the FRONT and MIDDLE camshaft bearings - at least those currently on sale -- are the SAME on 1275, 1098, and 948 engines. Only the REAR bearing is different on the 1275 blocks, as it's wider. The oil holes on the FRONTS are identical in size and position. The original drawings for these bearings, and their exact placement in the block must be sitting around somewhere. Somewhere, over the rainbow, no doubt.

Lawrence Slater

Back to the front MAIN bearing clearance. John Payne just confirmed that he had an engine with about the max allowed diametric clearance (0.0027") on his mains, and that resulted in a drop of circa 10-15psi oil pressure. Obviously the greater the clearance, the more oil will 'leak' from the bearing, and the lower the oil pressure. This will be exacerbated as the oil heats and thins. Today, I confirmed that just as the TCC fills completely with oil, the oil pressure drops circa 10psi. I've repeated this about 5 times now. Several people have commented that they see an oil pressure drop just before they get a cloud of smoke. The engine runs with minimal oil in the TCC for about 5-10 mins, depending on how cold it is in my garage. During this period, the oil drain holes keep up with the oil being fed in, and the level remains constant. Then, at a certain temperature in the oil, it thins, and the TCC rapidly floods with oil, overwhelming the drains. Eventually, the oil is thin enough for the drains to cope a little better, BUT, the level doesn't drop back to where it was before the flood. It just sits a little lower, and is presumably just low enough to stop the oil from being sucked up. I'm now not so sure that it is ONLY the camshaft bearing that 'leaks'. But it's impossible to see the oil from the front main as it's hidden. But I CAN see the oil from the camshaft bearing. I'll post a picture shortly. But there is no doubt that there is a sudden increase in oil flow in, accompanied by a slight drop in oil pressure. If the oil flow from the camshaft bearing increases, so too must the flow from the front main. My thinking is, that if the camshaft retaining plate is leaking too much oil, AND the front main is also on the upper end of diametric clearance, that could well explain all the extra oil in the TCC.

Lawrence Slater

New window for a better view.

Lawrence Slater

Here's a still from a short video with the new window. This is running at about 2500 rpm. The holes in the camshaft sprocket enable the cam retaining plate to be seen, and the oil flowing in behind the nose of the sprocket as it bubbles up at the top. And you can see the lower part as a 'river' of oil gradually gets wider and flows down the engine plate, to be dragged up by the chain when it reaches the bottom. This is running with a NEW flat camshaft endplate. You can see the oil flow gradually increase, as the engine, and hence the oil, warms up. But for 5-10 minutes, the flow is such that the drains can keep pace. This is only from the 1st few minutes. I'll post the video when I've compressed it and uploaded to photobucket.

Lawrence Slater

Lawrence That's dedication ... how many fngers have you left or did you take the fan off while fiming?

Paul Walbran

Hi Paul. Scroll back down in this thread to my post of 08 January 2015 at 22:17:52 UK time. I'm running my rad remotely with an electric fan. No risk to my fingers. :).

Lawrence Slater

Lawrence Mate, you deserve a medal for sticking to this I can understand why but crikey--- The bolts in the cover remind me of the back tyres on our old dirt bikes, we used to stick bolts through just like that for a bit of grip I wouldn't be surprised if all the Midgets your model with this breather system are oil suckers but maybee their drivers don't replicate the driving condition that allows oil sucking to occur That extra oil drain hole talked about early on might be the answer OR opening the drains in the main cap I don't think you would ever have to worry about the chain running dry as the holes are up high enough so that there would always be some oil in the bottom of the cover Minimum bearing clearance just as a guide for a road car-- half a though per inch of shaft and up to double this for racers

William Revit

"I wouldn't be surprised if all the Midgets your model with this breather system are oil suckers -- " Not all, but I reckon a whole lot more than know it. Maybe even the majority, but certainly most of those that ditched the breather for a catch can or other non-standard method I reckon. But still there's that question. Why didn't they do it when they left the factory? What changes in a rebuild that precipitates it on those cars that suck oil? Did BMC know about it? I now believe they did, and as Fergus posted with pictures 2 years ago, they modified the TCC with a baffle ring around the internal entry hole to the separator canister, to help prevent it. But does that work? I'll post more vid's as soon as I can.

Lawrence Slater

Here's the link to the video I posted a clip of earlier. http://tinyurl.com/ozr8voz This vid is only about 1.20 mins long, and shows plenty of oil in the cover prior to it flooding with oil that runs down the internal face of the cover. This is running with a NEW camshaft retaining plate. But if it's reduced the amount of oil in the cover, I can't tell. So I need another window. See next post for picture.

Lawrence Slater

Here's my first version of a baffle ring. It's placed at the same location as the internal entrance hole to the breather canister, and it's about the same size. Here's the video. There's a bit of condensation, but you can see the effect of the baffle ring. It keeps the hole clear. http://tinyurl.com/nlx87de BUT, a longer run does show quite a bit of oil getting to the window. So I need a bigger baffle ring I reckon, more like the one that Fergus showed on the later TCC prior to the A+ cover. Fergus, if you're reading this, what year was the later cover with the baffle ring from? Not the A+ cover, the other one.

Lawrence Slater

I believe the center one with the 3/4 splash ring is 1275 Marina,but remember all Marinas used single row timing chains not duplex. And of course the later Ital engine also kept to a single chain with tensioner.

Fergus Pollock

Yeah I reckon BMC new all about it as well Fantastic video - It still gets me that things look to spin backwards even with digital cameras You would think that shutter speed would be way different with more modern gear What about a curved baffle around the bottom of the camshaft sprocket stopping just short of the chain on both sides to help stop the sprocket whipping the oil around, thinking that if it were a bit more steady it might drain back a little quicker I know it's not the cause that you want to find, but could be enough to help settle the action in there I'm thinking that when these engines get a rebuild the crankshaft ,although standard probably gets a polish and new std bearing have probably a tiddle more clearance than originals and we end up with probably a thou or even a thou and a half more clearance than std which in turn could be enough to let excess oil pass through the gap I can remember back when 1500 Cortinas were new and standard engine bearings came in four colour coded sizes which were matched to the crank. They went up in 1/4 thou steps but all marked standard except for a dob of colour on the edge. Same thing happened with pistons and it wasn't unusual to have a couple of different coloured pistons in an engine I/m wondering if this sort of thing went on at BMC assembly and then at rebuild these sizes are replaced by a single standard size which would have to be the max. clearance item so that seizures didn't occur on the fatter cranks Ford Australia still use this method at assembly in the V8 and 6 cylinder cars and it's more important than ever with the tight tollerances being used for synthetic oils over willy

William Revit

Thanks Fergus. Interesting that they went from a 3/4 to full circle ring. In my last vid you can see the oil gathering at the bottom of my smaller full circle ring. I was actually thinking that it needed a gap at the bottom to let the oil fall away. I agree Willy. I now reckon that BMC new all about it, but as far as I can tell, they didn't tell jo public. --- "I can remember back when 1500 Cortinas were new and standard engine bearings came in four colour coded sizes -- " You're jogging my memory there. I had a 1500GT in my Consul Capri, and seem to remember that. Different grades of the 'same size'. And that's similar to what I'm now thinking too. The tolerances allowed in the crank and camshaft journal diametric clearances, are fine for the general running of the engine, and have no adverse consequences. But then the breather system was modified and the source of evacuation for the fumes was moved to the TCC, which has a lot of oil in it. When the engine was new, the amount of oil was handled by the oil drains ok. In the factory, they probably built to the bottom end of the tolerances. Even when the oil thins as it warms, it still never outpaces the drains. Then it gets rebuilt to a slightly greater, but still acceptable clearance in the front bearings. The oil thins, and the greater clearances allow a greater amount of oil in, sufficient to outpace the drains. As the oil heats and thins further, the oil drains cope better and the sucking stops. So why don't worn engines suck oil? Maybe they do. But not if only the rings are worn, only the front journals. People ignore worn rings for ages. You can. All you get is lower performance and a bit of smoke. But if the front main was worn enough, you'd drop oil pressure and do something about it. You may never notice the oil sucking because you worry more about the rumble. How about the camshaft plate? Well I reckon that comes down to a mixture too much endfloat, a bent plate, and combined with reusing the plate. The books say, check the endfloat, and replace if above quoted tolerance. But maybe the upper end of the quoted tolerance is ok for the camshaft/distributor timing, but no good for oil control into the TCC when it comes to PCV. I may have solved the problem with a properly sealed engine plate, and new flat camshaft retaining plate. I'v also taken som off the nose of the camshaft sproket and reduce the endfloat to a tight 3 thou" (0.003" - 0.007" quoted). It's hard to see, but it looks like there is less oil in there, albeit that there's still a lot once the oil is hot enough. So I have to bolt the standard TCC cover back on and go for a drive. Meanwhile, I wanted to see what a larger baffle ring would do. So I very crudely copied the A+ TCC ring. Here's what it looks like. Take a plastic blackcurrent juice bottle, a hot knife, and some silicon sealant. :). Interesting vid to follow too.

Lawrence Slater

Lawrence Just flicking around on the MINISPORT website and found these------------- Mini camshaft thrust plate (all sizes) - AHU2379 AHU2379- Camshaft thrust washer Goes behind the camshaft pulley in the timing chain area, make sure yours isn't flogged out! (all size Mini 850/1000/1100 camshaft bearing set in STD - AEC3046/VP956 VP956/AEC3046- Mini 850/1000/1100 camshaft bearing kit in STD This is a std cam bearing set for a 850-1100 engine (note that 1275 engines are not the same) you will require a cam bearing installer to fit (or see an engine builder) Mini 1275 camshaft bearing set in STD - AEC3063/VP989 VP989/AEC3063- Mini 1275 camshaft bearing kit in STD This is a std cam bearing set for a 1275 engine (note that small bore engines are not the same) Couple of things of interest 1/ Camshaft plates appear to come in different thicknesses if I read it correctly and 2/ There are a couple of nice pics. on there of the two different camshaft bearing sets showing the oil holes in the front bearing I'm not sure if I can see a difference or not, Wish they were both round the same way in the pics willy

William Revit

This is all very interesting, and great work from Lawrence. I am certainly glad that I left the bottom end of the engine alone when rebuilding at this time last year. It looked good, and I decided to trust the stated 85k km and it turned out to be a good call. I have one question for Lawrence. You are testing in a static environment, and it is clear that you are approaching a solution to the issue, but do you expect any difference in behaviour of the oil flow around your baffle ring when the car is moving on the road ?

dominic clancy

Willy. Yes. I noted that too. My new GLYCO camshaft bearings are marked as standard, which implies that there must be other sizes available too. Or perhaps that used to be the case in the past, but nobody undersizes camshaft journals anymore. -- Did they ever?. If the journal is scored, you get a new cam instead of grinding it. Also, as I posted earlier, the only difference between the 948/1098 and 1275 camshaft bearings, is in the width of the REAR bearing. The fronts and middles are the same. At least that's how it is NOW with those currently on sale. As to whether or not there USED to be a difference in the front bearings back 50 years ago, where is there to check on this? Dominic. Yup all the testing is stationary. What I've been concentrating on, is the oil fill to the TCC. On the road, the vacuum and blowby will vary more to some extent. But I consider both of those factors to be irrelevent compared to how much oil is in the TCC, and how it suddenly overfills. If the amount of oil present in the TCC for the 1st 5-10 minutes could be maintained, there is no way that oil sucking could occur. But something changes with respect to how fast the oil flows into the TCC. And I now think that, that 'something', is so marginal, that I doubt I can fix it. Especcially in the absense of any real information about the original bearing specs and EXACT positional placing with respect to the oil holes in the engine block. On the road, the revs will be higher than the circa 2500-3000 that I'm running in my garage. All this will do is fill the TCC FASTER, so won't negate my discoveries so far. However, it is just 'possible', that in sealing my engine plate gasket properly, fitting a new flat camshaft retaining plate, and reducing the camshaft endfloat to the minimum or 3thou", I 'MAY' have tipped the balance in favour of no suck, even if the TCC still has what appears to be too much oil in it. I'm not confident though and anyway I can test for this. All I have to do is fit the real TCC, connect the PCV, and see if oil is visible at the base of my clear breather tube. If I can see oil, it can be sucked up. I'm hoping to get around to testing for that today. Meanwhile, I'm about to post some of yesterdays results.

Lawrence Slater

This short video is a run from near cold, before the TCC floods. http://tinyurl.com/nejkb7o The larger baffle ring keeps the breather canister entry hole area, pretty well clear of oil. Then in this slightly longer video, as the engine warms up, the oil thins further, and the flow increases to a flood again, largely filling the TCC. http://tinyurl.com/kll6yd4 Eventually the oil is running like water, and even overtopping the baffle ring. I can't make the ring any deeper, than about 1/4", otherwise it will be hit by the spinning cam sprocket. But what I'm thinking, is that because it's larger than my earlier one, the circumfrence is such that it's 'flatter' at the top, and hence the oil doesn't run off so fast. So I'm going to make the top of the baffle ring, more 'peaked roof' shaped. That way less, or no oil will collect there, and drip over the cansister entry hole area. Well that's the theory.

Lawrence Slater

Going back to Dominic's question of how the oil will flow around the baffle ring when the car is moving. The answer is, I don't know. The engine will be bouncing with the movement of the car. Will that shake the oil off the baffle ring, or render the baffle ring ineffective? I don't know. I suppose if kept this TCC with the clear window in place, and put a small camera lense in front of it, we'd be able to see. But I'm not over confident that the perspex I've used would be up to the job on the road, and I don't have a small cam to mount there. If anyone nearby has a better sheet of clear acrylic, and a USB cam that they fancy strapping in front of my engine, I'd happily give it a try. Anybody? :)

Lawrence Slater

Here's my latest version. The internal entry hole to the elbow, is placed at the centre of where the entry hole to the breather canister would be on the correct TCC. If the baffle ring keeps my clear breather pipe empty, then when the PCV is sucking on the other end of the tube, there will be no oil sucking, and I'll have 'fixed' it. -- Even though I can't resolve the main problem of over filling, which is a disappointment, and a defeat. :(. But then again, if BMC left it like this, that's not my fault. :). Even if there is a little oil in the elbow and the base of the clear pipe, I would expect that the breather canister would now be able to handle this reduced amount, and separate the gasses from the liquid oil. After lunch we'll see. I feel a bacon sarnie and a cuppa coming on. :).

Lawrence Slater

Whoops forgot my picture again. Here's my latest version. The internal entry hole to the elbow, is placed at the centre of where the entry hole to the breather canister would be on the correct TCC. If the baffle ring keeps my clear breather pipe empty, then when the PCV is sucking on the other end of the tube, there will be no oil sucking, and I'll have 'fixed' it. -- Even though I can't resolve the main problem of over filling, which is a disappointment, and a defeat. :(. But then again, if BMC left it like this, that's not my fault. :). Even if there is a little oil in the elbow and the base of the clear pipe, I would expect that the breather canister would now be able to handle this reduced amount, and separate the gasses from the liquid oil. After lunch we'll see. I feel a bacon sarnie and a cuppa coming on. :). Hey Willy. Not studded tyres, it reminds me of an old diving helmet. Or something from Frankenstien. lol.

Lawrence Slater

Well all I can say is that it's an improvement, but not a complete success. Here's a still from the Video. I've circled the area below the baffle ring, that pretty much always remains clear. But as the video progresses, you can see just how much oil is sloshing around in there when it's at the height of flooding, before the drains catch up. The pipe though, -- and it has to be remembered that I have no separator canister on it --, doesn't completely fill with oil. And only a few droplets of oil are drawn fully up via the suction. Most of the oil in the pipe, appears to remain in the region that would be occupied by the larger volume of the breather cansister if it were there. So if applied to the normal TCC, this might work. Here's the vido link. http://tinyurl.com/o5tkg8g It commences when the TCC is in full flood. Even the baffle is overcome. As it progresses the baffled area clears and is eventually kept clear. But as you can see, the area in the circle always retains a clear area, although it's size varies. Returning to additional draining. That area in the white circle, suggests to me that if I were able to expand that by changing the shape of the baffle ring, it could be possible to drain the breather canister directly to there. The oil is falling and being pulled 'DOWN' in that region, and the baffle ring is keeping it clear. So if I drop another elbow out of the bottom of the breather canister, and connect it to the region in the circle, in theory it could drain the oil that enters the canister, before it's sucked up. Of course the question is, would the suction cause oil to be drawn in from below? I think not, as long as I can shape the baffle sufficiently to expand that area. If that wouldn't work, then I think a pipe dropped out of the bottom of the canister, and fed directly back to the side of sump at a high level, would do it. That way no additional canister would be required as a separator or flame trap -- imo.

Lawrence Slater

By Jove. I may have gone and done it. -- Again lol. I put the original TCC back on, and ran the engine from cold. Not a drop of oil in the breather pipe, after 15 minutes and all the way up to 190F temperature. Previously, even stationary, after running for a while I could throttle up and down and pull up some oil. Given that I've proved beyond doubt that the TCC is pretty much full of oil, I can only assume that the new flat cam plate, the sealed engine plate and the reduced endfloat, have reduced the oil in the TCC, just enough. Here's a link to the video of an empty breather pipe. http://tinyurl.com/mcbjs4m But I also just did something else. I found what could well be another joker in the pack, and took it out. As you can see in the earlier videos, the oil floods down the vertical inside face of the TCC, right over the entrance hole to the breather canister. Putting a ring around that area, reduces the oil flooding over that section. But the older TCCs don't have a ring. What might make the oil miss the entrance hole as it floods down the TCC? If the face was 'CONCAVE' on the inside perhaps? Looking at BOTH of my TCCs, I could see that they were 'BOTH CONVEX', as exactly the entrance hole to the breather cansister. This would encourage the oil flooding down the inside face, to drip into the entrance hole, and with suction, it would positively persuade it. So before I put the cover back on, I banged it 'concave'. Maybe nothing, but every little helps, as they say. And it's surprising how small things like this, can have unintended consequences Especially if with so much oil in there, it's on the edge of sucking anyway. Anyway, the upshot is, that I'm going to put my front end back on and go for a drive for a real world test. I'll let you know the outcome tomorrow.

Lawrence Slater

"By Jove. I may have gone and done it" But then again, I might not have. And in fact, I haven't. I put the front on the car and went for a cold drive. Oil sucking commenced after about 10 minutes. Definitely less smoke though, but still a failure to solve the problem. So now I officially give up trying to find out why, after circa 10 minutes depending on how cold it is, the TCC suddenly floods with oil. It's as if another oil feed is introduced. Maybe one day someone will stumble on all this, and explain exactly why the TCC gets so much oil in it after an engine rebuild. But I don't have the wherewithal or the inclination to keep looking. And the winter window for investigation is drawing to a close, as Spring -- hopefully -- approaches, rendering real testing impossible for another 6/8 months. So now I'm going to try a baffle ring on one of my proper TCC's. And if that doesn't do it -- and I'm not confident that it will, given just how much oil is in the TCC -- I'll go for a drain from the breather canister to the side of the sump, and or an extra breather to the side of the block. I thought about a 1/2" drain pipe from the 'downside' (direction of chain travel) of the TCC itself to the side of the sump, but I don't think that would be a good idea. For 10 minutes, there just isn't that much oil in there, and the chain might not get enough. So I reckon if I do drain it, it would be better to drain the canister, which after all, isn't supposed to have liquid oil in it anyway, -- only mist and splashes.

Lawrence Slater

Bug--r, I thought you had it The drain from the canister to the sump should fix it but I was really thinking you had nailed it the way you were going Cheers willy

William Revit

Sterling work Lawrence and I echo William's comments! Is it worth trying a new pipe and cap(unless you already have) given it solved my problem? I believe you are right that its marginal either way and perhaps this will be so with your engine.

Bob Beaumont

It doesn't make much difference what I do to the cam endplate. I fitted a new one. I pulled it off yesterday to check it. It was as good and flat as when I fitted it. I bolted it on at 6lbs. after about 20 miles, there are no gaps under the sides between it and the engine plate, and it was evenly worn, suggesting that the camshaft face and endplate are in even contact. Endfloat is 3 thou". There is a greater problem, that I can't identify, that causes a sudden and very siginificant increase in oil level in the TCC. For 10 mins from cold there is a reasonable amount in there. The chain is getting plenty, and the canister entry hole is clear. But within 15/20 seconds after that period, when the oil reaches a certain temperature, the TCC floods, and the breather canister internal entry hole is covered in oil. At that point if the PCV is connected, sucking is inevitable. No cap or pipe change would make a difference -- and anyway there's nothing wrong with mine. They could only make a difference if there was less oil in the TCC, and that's what I can't achieve, because I don't know EXACTLY why the flow suddenly increases, and WHERE FROM. My engine(S) may be extreme cases, but given other reports, I don't think so. This is evidenced by the later BMC introduced baffle rings. They knew there was a problem. DID THAT FIX IT? Are there reports of Marina engines sucking oil? MALC? To repeat. Something happens at rebuild to some engines, which results in an increase in oil in the TCC. Once the level increases, the amount may be marginal. I think that's the case because when fully hot, the TCC remains awash with oil, but the drains cope better with the tinnner oil, and keep the entrance hole to the canister clear. It's Goldilocks. Just too much oil in the TCC, and oil is sucked. Just below that level of oil in the TCC, and no oil is sucked. I looked at draining the canister directly to the sump yesterday. But the bottom of it it isn't significantly high enough above the sump, to get a decent downward flow. That leaves the baffle ring, and the 2nd canister to the petrol blank. I'll waste another 2 days on the baffle -- which I haven't yet tried on the 'real' TCC, and then give up, and make a 2nd breather canister connected to the petrol blank.

Lawrence Slater

MALC. Are you still following this? Is your timing chain cover, actually one from a MARINA engine? I ask because you mentioned in a previous thread that many of the ancillaries were from a 1098. If yours is a Marina TCC, complete with the baffle ring in it, then I can save myself some time by not bothering to fit one, -- since you have a 'marina' engine that sucks oil via the pcv valve.

Lawrence Slater

Lawrence, My engine is a bit of a mongrel, but I believe :-- The block is Marina, so is the oil filter. The front plate, the duplex chain and TCC are from a 1965 1098cc Sprite. I don't know if the oil pump, oil pressure relief valve is Marina or 1098cc. I've been reading all your posts and watching all your videos, thanks for the hard work ! The only thing I can think of that is causing the oil surge is the OPRV, it's open on start up, allowing oil to return to the sump, then as it closes the oil will be directed down the oil ways to the front of the engine. So why is it closing early ? Well,it could be that the oil going through the OPRV gets hotter fastest, causing a local oil pressure reduction, the OPRV closes and floods the front cover. It's the only 'active' part of the system except the possibly mythical oil bypass valve in or near the filter. Trouble is the OPRV is active in all engines and they don't flood. Malc

Malc Gilliver

Thanks Malc. Now you've confirmed that you don't have a baffle ring in your TCC, I'll go ahead with more baffle ring testing, if only to baffle myself a little more. LOL. If the oil pressure relief valve was open from the start, the oil pressure would be low to begin with, and then rise as the engine got hot. That would show on the pressure gauge. In fact the reverse shows on the gauge. It's not the oprv. But I suppose it could be a blockage in the feed to the rockers. If when the engine got hot, that feed suddenly blocked up, the oil pressure at the camshaft endplate would rise, and the oil fed to the TCC would increase with the rise. However. 1). All oil sucking engines would have to have the same blockage. I might have f*cked up twice, but has my Midget engine, built by others, been badly built too? And how about yours, and Norms, and Toms, and all the others? It seems unlikely. 2). If the rockers were starved when the engine was hot, it wouldn't take long before you heard them squealing and not long after that before they seized on the shaft. Edit. Malc. You said. " --- TCC are from a 1965 1098cc Sprite." Are you sure? I didn't think a 1098 had a breather on the TCC.

Lawrence Slater

Lawrence, Either the TCC is from the 1098cc engine, or it's from somewhere else.... I think the 'mongrel' nature of my engine it's part of my oil sucking problem. Malc

Malc Gilliver

FWIW, on the Vedette 948 engines (Frogeye engines converted to maritime applications) the sump was cast so that it carried forwards of the block by an inch and the front timing cover, also cast, was situated in such a way that all the oil in the timing cover all ran straight back into the sump through the large opening between the two parts. I have 2 Vedette engines here and neither of them leaked. I'll try to get some photos. You never know, it might help?

r thomas

Three holes in the camshaft pulley are for bolting on the drive for the waterpump which runs directly from the front of the timing cover. The inside of the sump is painted with red Glyptal(sp?) so you can see that all of the oil rapidly drains back down to the sump. Could the Spridget TCC have a copper waterpipe fitting brazed on that connects via a rubber hose to a similar fitting in the front of the sump?

r thomas

" I didn't think a 1098 had a breather on the TCC" Correct. The 1098 had the canister on the front tappet chest cover. Also, the 1098 wouldn't have had a duplex chain as standard. As for the oil pump, a 1098 would have a 3-bolt pump, whereas the 1275 is either 2 or 4-bolt, and the 1275 pump has a longer nose. They aren't interchangeable.

Dave O'Neill 2

Thanks for confirming those points Dave. Hi, r thomas. I was actually giving some thought today to what you describe. Namely, if the the TCC was deeper, the extra volume available would lower the level of oil in the TCC. I wondered about adding a thick spacer/gasket, that would hold the TCC further away from the engine plate. There are problems that prevent it though. 1). The breather canister is too close to the fan blades. This could be rectified by adding the same spacer thickness to the back of the fan blade. But would this put too much load on the water pump bearing? Or I suppose the mechanical fan could be abandoned in favour of an electric only as some have done. Personally I want to retain the original fan. 2). There isn't much room to move the TCC forwards anyway, because the position of the crankshaft pulley wouldn't allow it. But I wonder if the TCC could be altered to add volume above the pulley, by putting a step in it. Much as they did to the A+ version of the TCC, but for a different reason. As for a drain to the sump, as I said this morning, the bottom of the canister is too low in relation to the sump to get a decent downward flow. And anyway, as I said on the 8th, it might starve the chain of oil in the 1st 10 minutes.

Lawrence Slater

I should clarift that. And anyway, as I said on the 8th, it might starve the chain of oil in the 1st 10 minutes, --- if the oil was drained too quickly directly from the TCC.

Lawrence Slater

I'm going to try the largest baffle ring that will fit. Here it's being modeled by my spare engine block :). This one extends deep enough to penetrate the dish of the camshaft sprocket. There's a mm or so to spare, so I can pack it out and go deeper still as another test. But here's my prediction. I've noticed that once the oil begins to warm, the initial increase in oil seems to be behind the camshaft sprocket. Then the oil flows forwards through the two holes in the cam sprocket. If I'm right, then the baffle I've made, because it's so close to the sprocket, will fill with oil, defeating the purpose of the baffle. So I'm wondering if the later TCCs baffle ring, was only to control/divert a small amount of oil as it runs down the TCC internal face, not the huge flood that happens with my engines, and presumably the other oil sucking engines. I'll find out tomorrow, and make another video in the morning. BTW. The felt tip black circle adjacent to the camshaft nose, is the size and position of the internal entrance hole to the breather canister. And as you can see, the sprocket holes pass right over it. Now this leads me to another possibility. At first I thought the TCC filled from below. However it's now clear that it fills from above. So I'm now wondering -- although I dismissed it before -- if an open bottomed cover might be placed over the breather canister hole. No oil could then run in from above, and as I've seen from my previous experiments, the area under the entrance hole can be kept mostly clear of oil by a baffle, so no should be sucked in from below. Maybe a baffle ring and a cover, in combination, might do the trick.

Lawrence Slater

Lawrence idea no 4876.3 What do you think about filling the holes in the camshaft sprocket to reduce the amount of oil getting through to the front side of the sprocket through that way. Maybee a couple of welsche plugs ??? This would let your baffle work as a baffle instead of getting sprayed with oil all the time from behind the sprocket willy

William Revit

Hi Lawrence, I've been following this thread with interest and admire your tenacity! I'm not sure how much room there is in that TC but here's my idea - a bit weird but read on... Is it possible to put a form of 'snorkel' within the breather take off? This would consist of a tube (of copper/brass? about 4mm dia?) that would feed down from the canister and into the TC and up so that both ends are above the level of the hole between the TC and CC. The ends of the tube need to be looped so they point downwards to help prevent direct entry of oil. My thinking is that with this in place air would always be able to get through, which would prevent huge 'gobs of oil being sucked up? Even if some oil did get into the tube it would only be a small amount and soon be sucked out if the main hole is blocked with oil. Picture attached is taken from a MMOC post and edited by me! Jim

J Smith

I don't know willy. Most aftermarket sprockets have more than 2 holes. Are they there to balance the sprocket or to lighten it? If I plugged the holes, how would I balance the sprocket again ? If not balanced, the engine would vibrate pretty badly and ruin the front journal I'd have thought. But I have thought along those lines. I thought of adding an additional thrower, like the one on the crankshaft. See my pic, -- thrower in red. If I made it large enough to cover the holes, it might keep the oil away. And being just a flat disc say .5mm, as long as I drill dead centre it should keep the balance. I'd have to reduce the depth of the baffe to accomodate it, so first I'll see what my larger baffle does on it's own. Interesting thought Jim. But I believe the entire canister also fills with oil as well as the TCC. So the snorkel would be submerged at both ends. I think the only ways are: 1) Reduce the level of oil in the TCC. Failed. 2) Prevent the oil, irrespective of level in the TCC, from entering the canister. So far failed. 3) Drain off the oil from the top of the canister, BEFORE it reaches the PCV valve or Y piece, by connecting the PCV system to the side of the engine block as well. This would also split the suction, and aid draining within the TCC. This at least has the merit of being proven to work already, and is what I've favoured all along in the absense of finding out how to do item 1) or 2).

Lawrence Slater

Lawrence, I think the canister is filling with oil because it is being sucked into it. If there was an air bleed tube, then the oil can't get sucked in? Jim

J Smith

Jim. See all my previous descriptions and videos. But even if you were right, the TCC is full of oil, so the snorkel could never suck in air, only oil, which wouldn't drain away, it would be sucked up the canister. And even if there was a pocket of air at the top of the TCC, there is still no room to put a tube in there to collect it.

Lawrence Slater

Hadn't thought of a big slinger , sounds good I like the idea of it If the top half of your baffle ring ran real close to it and the bottom was more open as you suggested earlier it might just work It would be interesting to watch in action through your see through cover willy

William Revit

I decided to put a cover over the entrance hole to the breather while I was at it, and do the test with the large baffle ring, and cover together. Well, as I predicted, the baffle ring filled with oil. And because the ring was full of oil the cover made no difference. Oil was sucked up. There is simply no way to prevent it -- that I've discovered. Even if I make the large thrower for the camshaft sprocket, if it temporarily prevents the oil being pushed towards the entrance hole, it still won't prevent the total filling of the TCC. 10 minutes, reasonable amouint of oil in the TCC. The entrance hole to the breather remains clear. Then the TCC begins to fill, and is flooded, until the breather entrance hole is swamped. Oil flows into and UP the breather pipe, and that's with NO suction. As soon as the PCV is connected, oil sucking commences. Eventually the oil level drops, as the oil get hotter and thinner. But that goldilocks moment can't be prevented by anything I've done so far. My list of options now reads for the 1st 2 points --- : 1) Reduce the level of oil in the TCC. Failed. 2) Prevent the oil, irrespective of level in the TCC, from entering the canister. Failed. So I think the only routes left open now, are draining and or split suction I've had another look at draining directly from the bottom of the breather canister. As you can see, there 'might' be enough of a drop after all, to ensure a drain to the side of the sump. I'm not concerned that oil could be sucked from the sump though, as the MAX level is too low, and a surge up the side seems unlikely. Plus a.o. arnold, Netherlands had connected his here too. I'll fit an internal shroud of some kind on the inside of the sump, to prevent oil flowing down the inside of the block, from entering the new hole. My concern is though, that the suction from the PCV, might simply prevent the oil draining from the bottom of the canister, just when it needs to, when the TCC is at it's fullest. But it'a pretty simple easily reveresable mod, so I might give it a go before going for the petrol blank. I also think it would be neater than than an extra oil/air sepearator on the side of the engine. I'll drop a 20mm copper pipe into a couple of elbows and see what happens. It does mean I have to get the bloody sump off to change it though. But what's to lose? I love being cold in my garage lol. The other alternative is that I do the split suck method to the pre-drilled petrol blank on my Midget. That would be easier/more pleasant in this cold weather, and it would prove to me, that it definitely works, on 'my' oil sucking engines.

Lawrence Slater

Lawrence If you are going to go ahead with the drain to the sump Just looking at your engine pic. Do you think it might be better to go into the sump on the front corner. It would be a more direct downhill run for the oil I'm just a bit worried that if you go back near the centre as shown that the draintube will be going back fairly horizontal and with all the bits spinning around in the sump back there, there could be the possibility of the combination of all the huff and puff going on in there and the horizontal pipe being enough to restrict the flow back to the pan just a thought willy

William Revit

How about moving the breather canister aft so that it is drilled through the engine mounting plate and welded to the rear face, next to the front tappet cover vent on a 1098? Treating the symptoms rather than the disease, though. It would leave more space for the fan and add some height to the base of the breather can. Taking the line of thought to the next step, having the TCC venting downwards into the sump and having the breather connected to the sump via a tall neck...would that help? I had a 1275 sump with such an arrangement on it. Not sure if it helped because the rear main bearing studs threads were sloppy and the engine lost loads of oil before it finally departed this life on the M5 motorway one night (after Spridget 50). Oh, one other thought. How much does the camshaft stretch when heated to running temperature? Enough to push the cam endplate outwards?

r thomas

R thomas. The camshaft, if it were to stretch, would have plenty of room to move back into the pump. The only forward thrust comes from the distributor drive. I've given up treating the cause. Now I'm just treating the symptoms anyway. And as long as that works, I guess I'm happy. I am though disappointed that I couldn't prevent the problem by finding a simple cheap to rectify cause. I think all that remains is the possibility that there is too much diametrical clearance in the cam and crank journals. Not enough to cause a running problem, but enough to allow too much oil into the TCC for a brief period of time. I could buy new camshafts and have the front bearings tighly reamed to the absolute minimum clearance quoted. I could do the same with the crankshaft, and make sure it is ground to the minimum for clearance. But that's too expensive, even if it was a definite cure, given that there are several possible effective work arounds that still retain the PCV. I don't mind spending my time, but I hate spending too much of my money. LOL. Willy. You might be right, but a connection to the front of the sump, is more likely I would think to cause an oil surge up the pipe. Brake going down hill, foot back on the throttle, and up it sucks. I've decided to 'fix' the Midget first, since that has a pre-drilled petrol pump blank. Tom's method is the neatest I've seen. But the ally block he used is expensive to buy from the US. So I'll see if I can make something similar. Meanwhile, how about a cyclone from a Land Rover? http://www.ebay.co.uk/itm/LAND-ROVER-DEFENDER-DISCOVERY-1-TDi-ENGINE-CYCLONE-OIL-BREATHER-ERR1471-/371072732689?pt=LH_DefaultDomain_3&hash=item5665a88e11 By all accounts thet are about the size of a tin of beans. The oil out pipe returns to the sump. The chap I spoke with says they can be taken apart. So all I would add is a ss wire mesh to act as a flame trap.

Lawrence Slater

Lawrence, I suspect that on a road engine you don't need two breathing points. If you put one at the mechanical fuel pump location I wouldn't think you would need the one on the TCC. As I recall, my 1275 has both, but it was built for autocross work and is souped up. I had to bore a hole through the block because it was closed like the one in your photo. Were your recent tests done with a cam bearing that was flush rather than recessed? Charley

C R Huff

May be a simpler solution is to blank off the TCC vent and remove the canister etc completely - earlier engines didn't have one there - it can then fill to its hearts content. Then fit the oil separater canister at a suitable level to the fuel pump boss instead with the vent to pcv etc. R.

richard boobier

Making a 2nd breather point at the petrol blank, retains some ventilation of the TCC, which may or may not be needed. What I haven't ruled out doing, is putting a very small restricted air filter on the TCC breather canister, and only connecting the PCV to the new petrol blank connected breather canister. That way air will be drawn IN down the TCC, so no fumes escape to the engine compartment, and any pressure in there is relieved, that 'might' otherwise find it's way out of the TCC crankshaft oil seal. Charley. Almost flush. I won't know the exact state of that bearing until I pull the engine out -- it's in my Sprite. And I intend to do that, as soon as I've got the MIDGET engine to stop sucking oil, by using the above method. Then, 'IF', my Sprite engine's front camshaft bearing is in the same scored state that my spare engine's bearing is in, it 'may' be possible to point to that as a cause. But I'm not holding my breath on that one. ;).

Lawrence Slater

Have you thought of using an A+ TCC? It has a slightly bigger capacity so it may delay the time taken for the oil to get to the sucking point before it gets thin enough to drain back. Rob

Rob aka MG Moneypit

Yup, I wondered about that Rob. If I had one, I'd try it, but don't fancy buying one, given just how much oil is in mine. However, if someone wants to send or bring me one, I'll bolt it on and give it a go, and then they can have it back, or sell it to me, dependant on the outcome. But I thought it wouldn't work with a duplex?

Lawrence Slater

A+ TCC works with duplex if you grind the lip off the inlet to the canister.

r thomas

Lawrence, You mention allowing the TCC to become an air inlet. I thought the inbound air was supposed to be metered, though I am more familiar MGB. Some of those used an elbow in the valve cover with a restricted orfice, or I think some used a restricted vent in the oil cap. Isn't the A-series the same way? If so, I don't think you want to loose the restriction. Charley

C R Huff

With my engines TCCs' already full of oil and sucking, I wouldn't want to grind off the baffle ring on an A+ TCC, as it may do some good. And I wouldn't be able to return it then either;). Charley. Yup, there's a restriction in the oil filler cap. That's the air inlet for the TCC canister to suck on. By putting a breather on the petrol blank, BOTH the TCC canister and the petrol blank will suck on the same source -- oil filler cap -- , which will reduce some of the suck on the TCC canister, and hopefully stop the oil suck. Since there is less suck on the outside of the TCC canister, it should also aid the oil draining in the TCC. If I leave the top of the TCC canister completely open, the air will be drawn DOWN through it, instead of UP through it. Thus 'definitely' NO oil suck from the TCC. But as you say, that alone would allow too much air flow into the PCV at the carbs, and would probably circumvent the venting down through the engine block. That's why I said I'd fit a 'restricted' air filter on the otherwise open TCC canister. Just enough filtered air in, to pull in through the top of the TCC and into the crankcase, to evacuate any water vapour that might that might otherwise condense in there. As for my Midget petrol pump blank, you can see it was leaking oil. It's a big hole, and I wonder just how hard oil is thrown at it. The camshaft spins above it, and throws oil downwards. So too do the crankshaft big ends, but again, not directly at the hole. I reckon mostly it's splash that runs down towards it. But I'll soon find out, as you'll see from my next pictures.

Lawrence Slater

Too much rain to finish today. Hopefully I can do a test tomorrow. I haven't yest made the block to mount a breather canister the same as Tom's done. So as a prototype test, I'm using a tank connector through a home made blank plate. The elbow on the inside sits nicely inside the block, and will prevent any oil running down into the tube. And yes, I've checked, it's clear of the crankshaft by a country mile. :). I also want to see if I can utulise the breather canister that was on my test TCC. -- I don't like to see it go to waste. (Dave O'Neill :). It's set at an angle though, and that means I can't quite squeeze it in behind the heat shield without altering it. So for now, until I alter it to mount through the bottom face, just as a test it'll be like this. Because the main tube is going to be horizontal, oil may collect in there sufficiently to cause a reservoir that could cause another oil suck source. So as a first run, I'm going to block the TCC off. That way I'll know where the oil is coming from if it does suck some up. Then if it doesn't suck, I'll reconnect the TCC canister and have another go. If it does suck, I'll try my 2nd prototype mounted via the tank connecter. See my next post.

Lawrence Slater

28mm x 15mm reducers make for a really nice canister. Cheers for the idea Tom. As soon as I source a suitable block of ally, I'll make a version of the minimania block http://www.minimania.com/part/C-2A265/Crankcase-Air-Breather-Kit-Mechanical-Fuel-Pump-Mounting ), and mount my copper the same way. I'd buy the real thing, but although the price is $38.21, shipping is another $31.98. Pity you can't buy them in the UK. But for now, just as a test, I'll put this together with gaffer tape.

Lawrence Slater

If it doesn't work, I reckon that with a small extra outlay you could start a new venture-----------whisky lol willy

William Revit

lol willy. :).

Lawrence Slater

This was running with the TCC breather canister blocked off. I'm pleased to report, that even with the horizontal feeder pipe leading to the separator canister, not a puff of oil smoke was detected. And there was a good strong suction at oil filler cap neck. So I know it's working. Tomorrow, I'll whip it off, and see how much if any, oil has collected in the horizontal pipe. Then I'll connect in the TCC canister as well with a T in the line going to the Y piece. That'll be the acid test.

Lawrence Slater

All good so far then These things must have been really that close to sucking oil when they were new-- BMC must have known about it, surely they would have had some suckers when they were under warranty, . you'd think.? cheers willy

William Revit

But nobody admitted to me if they did know Willy. Back in the '80's I regularly went to BMC dealers and garages to see if anyone knew what was wrong. Nobody had a clue. I even rang the BMC/BL technical department at Oxford, and spoke with the guys who should have known. I told them my engine was sucking oil from the TCC. They just told me it couldn't be happening. In case you or anyone wants to call them, I've still got the number written in my Haynes manual. It's 0865 778941. But nobody will answer now, they've gone on an indefinite tea break. lol Unless someone takes up from where I've left off, and digs a little deeper, I guess we'll never know the exact cause and direct solution.

Lawrence Slater

Reminds me of VW a bit I had this owner of a VW Bora that was complaining of a bad engine surge at low speed Rang VW -Never heard of it they said several times Driving the thing one day trying to sort it and happened to notice the dashlights surging when the motor surged Checked the alternator and it was flicking up to 20voltslike 20-12-20-12 Rang VW to see if they wanted to replace the alternator or have it rebuilt locally Mr.VW on the other end of the phone says -- wait for it We'll send another alternator from a different manufacturer because the brand that I had there has been giving them a lot of trouble-They get bad enough to make the engine surge on some cars he said-------- I decided they only tell you what they want and nothing else, --A bit like BMC is my guess willy

William Revit

You might be right Willy. I guess if it had been known about, and officially acknowledged, they might have had a whole load of expensive claims for engine rebuilds.

Lawrence Slater

Far be it for me to tar all OEM's with the same brush but..... They're all the bloody same... Only tell you what they want to know or when you can prove the source... On my first C5 back in 2001/2 when you touched the brake the cruise control would slam off sending a shudder through the whole car. Dealer said "we've never seen that", Citroen said speak to the dealer... Then at a service they said "we've updated the software to the latest version for you" guess what was fixed? The same again on the next model of C5 for a different fault!! Liars the lot of them ;) And I won't mention VW.... A safety recall in the States but not in the UK for the same fault!! Go figure.. Best of.. MGmike

M McAndrew

arn't bmw the same they are in denial about a problem with the power steering motor on minis

mark 1500 on the road Preston Lancs

It's been the same from the beginning of motoring time. Nobody told the first owner drivers, BEFORE they bought the car, that AFTER they bought it, someone would have to walk in front waving a bloody red flag. ;). Took the lashed up breather cansiter off again today, to see if there was oil in the horizontal pipe. There was. But it doesn't cause a problem at all, since it doesn't get sucked up, and if it gets above a certain point, it drains back again, because the CC isn't full of oil, unlike the TCC. I could leave it like this, but I'll alter it for bottom entry so i don't have a 'stagnant' pool of oil sitting in there. Then I connected the TCC in, and took a long drive. Again no oil sucking. But it was pretty mild today by the time I went out. It should be colder tomorrow for a more realistic test, but I don't think it's going to suck any oil at all. One thing I noticed immediately though. The engine is running much better. My TCC is so full all the time, that I reckon even without the obvious sucking cloud when cold, there was a small amount of oil constantly being sucked into the carbs when it was warm. Now though there is nothing at all by comparison, other the the 'vapours'. So I reckon it's worth doing this anyway. And apart from tommorows cold test, I reckon that's just about the end of the story for oil sucking engines via the TCC, unless someone want to keep trying to find out why the TCC gets so full, and how to stop it.

Lawrence Slater

500 unbelievable

William Revit

No suck on previous Mki version from cold this morning. MKii lash up in pic below. . No oil suck, when warm. Should be frosty tomorrow for a better test. Then I'll get hold some ally to make a mounting block to enable this Mkii version to be mounted from below, and solder it together instead of tape it. Although I might keep one joint taped around the large diameter of the reducer, to enable it to be inspected/cleaned. I think I'm going to keep the side entry to the Mki version, but make the feeder pipe slope down towards the engine instead of being horizontal, to facilitate oil draining from it.

Lawrence Slater

Lawrence, Looks nice. With both TCC and fuel pump hole hooked up, I suspect that even if the TCC fills with oil, the path of least resistance to the block will prevent the oil being sucked up. I do wonder if you might put your block vent under the oil level on a hard turn. As I recall the hole I put in the side of my block was about 1 inch and I don't think I had any plumbing extending into the engine. I believe I am running both the block and TCC vents. Maybe if the block vent submerges on hard cornering, the TCC will be clear and prevent the oil sucking from the block. Charley

C R Huff

I like it Good idea having a larger diameter hose going up to the Y piece, With that,even if it did get a bit of oil up there, there would be plenty of area and less velocity so you would think it would drain back easily and allow for air to suck through it without sucking oil all the way up I think willy

William Revit

Will soldered joints stand up to the vibration?

Dave O'Neill 2

Early drive in the frost this morning. No oil suck. So just as Tom Charley and others have demonstrated, even with a tcc FUL of oil in the winter warm up period, this cures oil sucking. I always figured it would, but I'm still fed up that I couldn't solve the main issue. Hi Charley. The petrol blank hole in my Midget block is appx 30/31mm diameter, and was pre-drilled(cast) by the factory. I assume it's an early 1275 block, even though my Midget is a '73. Obviously not original to the car. And I tested that very thing about oil surging through the hole. When the engine was good and hot, and the oil runny like water, I hammered it around a roundabout. 3 complete revolutions. (Note: We go CC at roundabouts in the UK). People must have assumed I couldn't decide which exit to take. lol. Anyway, even with hard cornering to the right, with the back almost kicking out, no smoke emerged. No evidence at all that it caused oil to go up the pipes. I'm going to remove the "internal plumbing" and see if it makes any difference. Looking at the block, it's clear that the petrol blank entrance hole is recessed internally. It may be that not as much is flung/drips into the recess as I first thought. I'll make a clear plastic window for the petrol blank and run the engine for a look. Willy. The pipe to the Y piece looks larger than it is. Internal diameter is standard 1/2"(13mm). But I agree with you. Remember Bob's experience? His hose was collapsing, and a new one, -- with a clear internal bore -- seems to have done the trick for him. So I wonder what might be the effect of using say a 20/25mm internal bore, and reducing it at the ends to fit? Would that slow the passage of oil sufficiently to allow it to 'settle' back? Maybe, but on my engine at least, with a proven FULL TCC, I want a CERTAIN resolution to this, that isn't always on the edge. So unless by some miracle I can discover the cause of the overfull TCC, I'm sticking to the dual vent solution. Dave. I don't know for sure. But the pipes penetrate the fittings a good way, and there's a goodly amount of solder in them when set off. So I wouldn't think the vibration would cause a problem. Especially as the maximum u measured the CC pressure at was 3psi, and that will be divided anyway at the TCC and the petrol blank. I think the MKi version with the long feeder pipe is the most likely to suffer from the leaking solder joint. But anyway, worst case it will weep and need altering.

Lawrence Slater

PS. I said, "Especially as the maximum I measured the CC pressure at was 3psi, and that will be divided anyway at the TCC and the petrol blank -- ". Won't it? Is that right? I mean the pressure will be being relieved at the TCC vent AND the petrol blank vent, plus the oil filler cap and the dipstick and the rear scroll. But in effect, the oil filler cap, the dipstick and rear scroll, will only sense 'vaccum' rather than pressure, leaving the pressure divided between the TCC and petrol blank vent. ? Is that bollocks? lol.

Lawrence Slater

Lawrence, The petrol pump hole/cover plate was only on the last of the 1275's OS&M notes change at engines 12V778FH about Nov '73 - so your engine may be original if a '73 car. R.

richard boobier

bollocks I reckon While the hoses are connected to the carbs I can't see that you will ever have positive crankcase pressure There would be a slight vac. if anything I would think/guess Also, maybee a little support bracket from the top of your new still to something might help the solder joints to live longer - or not Congrats for sticking with it willy

William Revit

Richard That part of OS&M has been proven to be incorrect in the past. Although it is the later engines that had it, it started much earlier. I can't remember exactly, but it may have been from the start of 12v production. I will have to go and check my spare engines again!

Dave O'Neill 2

Is there an official spring strength for inside the standard PCV? I was wondering what vac was required to activate the valve.

r thomas

Just found the thread in the archives, regarding the petrol pump blanking plate. It is entitled "72 Midget owners, help!" I can't believe it was nine years ago!

Dave O'Neill 2

Dave, That's interesting - my original engine (I'm now looking for the remains of the tag to confirm its original !) from my Oct '72 build (dynamo car) noted as a 12V586 has pump filler plug and no bolted plate. Perhaps others can confirm if their 12V's have the plates fitted. R.

richard boobier

I'm glad I've never met you on a roundabout Lawrence..... >>(Note: We go CC at roundabouts in the UK)<< :-) Jim

J Smith

Hello Lawrence I posted a message on this thread about three weeks ago- now I'm scrolling for ages to get to the end. You've done so much practical research on this so could you give a brief summary on your thoughts. I always thought folks talking about condensing vapours sounded a bit unlikely for the oil volumes were talking about and you've shown. Is a reconditioned engine the one common denominator? Could something in aftermarket parts be implicated? I'm sorry if you've already covered this but I would appreciate your current viewpoint. Could some part of a recon engine allow more oil into the tcc. Oil pump. Cyl head gasket oil holes? Kenneth

K munnoch

Oops. Typo Jim. My fingers are so used to typing CC for crankcase pressure, they have a mind of their own now. But I have to confess to going the wrong way around in the past, when I was a few sheets windward in my youth. lol. Why did the latest 1275's have petrol pump blanks? Were they expected to go back to mechanical petrol pumps? Good news then that my engine is probably original. I think if it had been a recon, it would likely have got one with the plug, in part x. Which is the reverse of what I thought was the case, as I assume the plugged ones are more common. Yup, a support bracket might be well worth it Willy. As for CC pressure, did you see Guy's blue rubber glove experiment? I replicated it on my engines. At high enough revs, even with the PCV connected, the glove inflates slighly, indicating some pressure. But perhaps with two active vents, it wouldn't. That's worth a test as it happens. I'll try it tomorrow. r thomas. No idea. You can't buy that spring on it's own, and I don't think it's strength/length is quoted anywhere. Kenneth. The timing chain needs oil. It comes primarily from the front end of the camshaft, via a hole in the camshaft retaining plate, once per revolution when the camshaft groove aligns with it. Some also escapes from the front camshaft bearing into the space behind the reataining plate, and weeps through behind the plate all the time, and also through the partially covered hole. Some also escapes from crankshaft main bearing. The pump provides the pressure. No pressure no oil in the TCC, so clearly pressure is a factor. But the pressure relief has been ruled out. So the only faults that can be causing the TCC to over fill, are basically that the holes/gaps through which the oil enters the TCC, are too big. On my experimental engine I've ruled out the retaining plate, by fitting a new one, ensuring that if fits flat, and that the endfloat is the bare minimum. That leaves the crankshaft and camshaft diametric clearances as the only remaining culprits, since the oil can't get in from anywhere else that wears. Badly spec'd replacement parts? Well possibly the camshaft journals on new/reprofiled cam's are undersized, and or the crankshaft main journals are ground too far. That's my thinking, but I'm not about to spend a load of money on a new camshaft or crank grind to prove it. Although. As it happens, my experimental engine does have a slight rattle on the big ends. If the mains aren't perfect, I'll maybe get a fresh grind and ask for it to be done to provide minimum bearing clearance.

Lawrence Slater

As an interesting comparison, I extended my breather hoses and ran the last 5 inches in clear pipe. I took these pictures today. I'd already driven the Midget with this clear pipe connected, whereas the Sprite was stationary in the garage. But BOTH my Sprite and Midget engines were well and truly hot when I took the pictures. Both engines were running at 3000rpm. BOTH engines suck oil with only 1 PCV connection to the TCC. The Midget engine on the left has 2 PCV vents connected. The Sprite on the right has only the TCC connection. I've now driven about 35 miles in the Midget with the double PCV vent connection. I took off the pipe that connects the top of the T piece on my home made copper breather canister to the Y piece on the carbs, and had a look at the insides. This was a brand new length of 1/2" rubber heater hose when I connected it the other day. Originally it had a whitish colouring on the insides. It is STILL completely clean and whitish. As you can see from the clear tubing in the LH picture, there simply isn't any oil at all being drawn up. Not even mist so far. I've taken the clear tube off again as the wall is too thin. But I'll keep an eye on the insides of the rubber tubing, and take a look every 50 or so miles to see when/if it begins to collect an oily residue.

Lawrence Slater

Unbelievable I used to have a clear breather hose just like that on my old Midget hillclimber - It ran from the sideplate up to the rockercover and the main breather went out from the back of the rockercover to a catch tank When I started it up cold methanol would get into the sump a bit and the hose would go all milky until the oil warmed up and the excess methanol steamed out. I used the hose as a guide for when it was warm enough to race. Got a pic somewhere, I'll hunt it out willy

William Revit

:). Small world Willy. I've probably never had an original thought/idea in my life. LOL. This deserves to be shown for it's minimalist simplicity. But what I'd like to know is, was it connected to the PCV, and was there any oil drawn up the pipe if it was? If there wasn't any oil draw, then this has to be the way to go. It appeared in the archived thread "crankcase breather", posted by John Collinson, Devon, United Kingdom, 29 September 2007 at 11:37:41 UK time. John. Are you still in attendance? I found an email address for John, and am hoping for a reply. David Billington also posted his version of petrol pump blank venting in the same thread. David, do you by any chance know if in the pic below, the pipe was connected to PCV or just left open? And did you later modify your own version and remove the sump drain?

Lawrence Slater

Found it, not much of a pic. but-

William Revit

Lawrence I doubt that John Collinson would have had a PCV on his race car. Just plumbed to a catch tank, I should think.

Dave O'Neill 2

I had trouble viewing this thread before with Firefox and now Chrome is having issues displaying it properly, starting about 4 posts ago, and the image tag just shows up as text not a link.

David Billington

Cheers Dave. I didn't know it was a race car. So really only done for extra CC pressure relief. David. It must be something other than your browser then. Could it be the operating system or an add-on in the browsers being out of date? I'm using FF 35.0.1, and Chrome Version 40.0.2214.111 m. My photobucket video links only work for me in Chrome though. Willy. Those are long inlets.

Lawrence Slater

This is the only A-series I ever had that didn't spew oil. Scouring pads removed for cleaning.

r thomas

Doubled up engine stays? How much did that engine try to twist? Ah I see one is an earth lead. Not a conventional Spridget by the looks of it. ;).

Lawrence Slater

I have struggling with this for a long time, even more because I run a supercharged sprite, so I do Always have suction at the inlet. The main modifications I did: - oil pan (see pic) - suction (also) via exhaust (evacusump or some name like that) - I use an air / water seperator from a aircompressor to seperate the oil from the air. Catches about 0,5 liter per 1000 kilometer (!)

a.o. arnold

also an idea / sollution to seperate oil and air another way

a.o. arnold

Hi A.O. The same could be achieved with the Landrover serarator I posted a picture of a week or so ago. here' s reminder.:). Meanwhile, I can report that my copper "whiskey still" type canister is doing a grreat job, and my engine hasn't sucked a drop of oil. I checked the tube to the Y piece yesterday, and it is still bone dry on the inside. Still no oily residue whatsoever. But as importantly, NO SMOKE. :). Also meanwhile, I've removed and stripped my experimental engine down. The front camshaft bearing is FLUSH with the block face. And waht's more, is in PERFECT CONDITION. No scoring. Wihout the pushrods pressing down on it, I checked the diametric clearnce of the front bearing/journal, and it's LESS than 0.002" I don't have a 1thou" blade. But the max quoted is 0.002". So I reckon that the front camshaft bearing isn't the cause of too much oil in the TCC. Likewise the front main bearing. Well within the quoted clearance spec. So where the f*ck does the sudden increase in oil come from? Before my clear window experiments, I reckoned the TCC over filling with oil was a gradual process, that eventually overwhelmed the drain holes, until the oil was thin enough to drain fast enough. And from then on, until the engine is dead cold again, there is a much reduced amount of oil in the TCC. But now it's clear that for the 1st circa 10 minutes or so, or sooner if driving faster perhaps, the TCC has a 'normal' amount of oil in it, which then very quickly increases. And although as the oil warms and thins, the level drops sufficiently to stop sucking, it remains far higher than it was in the 1st ten minute warm up period. Clearly there is enough oil to begin with. So why the sudden increase? And more importantly, HOW? It's as if there is an additional hidden oil feed, that only happens when the engine is warm enough. Is there some hidden 'gap', that only opens up when the block warms up, and thence remains open until it's cold again? The only way to be sure now, would be for a NON-OIL SUCKING engine to have a window fitted to the TCC, to see if it too has a more or less full TCC when running, but far less in the 1st 10 mins.

Lawrence Slater

Hi Lawrence Glad to hear you are still smokefree I'll probably get jumped on from everywhere for this but I'm still inclined to think that 20/50 oil might be a tiddle on the thick side for cold weather operation While I understand that the 50 side of things is probably about right for hot engine running, I still think that the startup viscosity of 20/50 is too thick for the colder months and think 15/50 or even 10/50 would be a better option and would drain back a lot better at low temps and still retain it's viscosity hot willy When your Midget was new and didn't suck oil, what was the recomended oil in the handbook - just out of interest

William Revit

I always ran 20/50 in all weathers and never sucked oil. As has been mentioned before, the sudden surge *may* be as a result of the O/P relief valve shutting.

Dave O'Neill 2

The standard oil spec is 20:50. I've also used 15/50 and mobil 1 0:40. Still sucked oil. And as Dave points out most people use 20/50 and don't suck oil. Hi Dave. Why would the valve suddenlty close if it's over pressure? How to test that? All three of my engines? Plus Tom's, Malc's, Norm's, graeme's, etc etc etc? And there is no sign at all that the valve is sticking. It doesn't seem likely. But clearly something happens.

Lawrence Slater

I was thinking along the lines of cold thick oil on start-up, with associated high pressure. As the oil starts to heat up, it thins and the pressure drops enough for the relief valve to close, resulting in an increase in flow into the gallery. The oil has not warmed/thinned sufficiently to drain out of the TCC fast enough at this point.

Dave O'Neill 2

Lawerance You have created another catastrophic issue The place you drilled a hole on the block to vent the oil back into the sump is very weak, on high RPMs this is the place where the engine likes to flex alot and the reason for a center main strap on the center bearing cap I fear that now that you have bored a hole in that same spot and added a couple of bolts to a tube ... this could break down fairly fast at a decent RPM Id seriously look at a getting a center main strap and having the main cap machined and new ARP hardware made for the strap and main cap Prop

Prop and the Blackhole Midget

Dave This is my main contention with this entire thread, and the reason that BMC engineers were never aware of the issue The oil is just to cold at start up during the winter ... let the engine warm up at idle for 5-10 minutes, before driving... Problem solved Ive already proved this on my car....at 10 degrees F. And no warm up time it sucks oil and does exactly like lawerances engine But if its 10 degrees F. And I let the engine warm up 5 -10 min before I drive it... ABSOLUTLY NO sucking oil issues, no huge cloud of smoke out the exhaust with in 3 miles, the engine runs great In away, this thread is like how to avoid burning the roof of your mouth while drinking hot tea straight from the kettle at 212 degrees F. Most people let it cool or blow across the top of the cup, Rare does one reinvent the cup to drink the fire hot drink in one gulp This entire thread really is that simple... let the engine warm up 5 minutes (problem solved) Prop

Prop and the Blackhole Midget

What about this experiment ... Remove the oil filter and completely drain the oil, not a drop left in the engine, let sit overnight when its cold. next in the morning with the engine cold, install a new oil filter heat the oil up on the stove to 300 degrees F. Immediately pour the hot oil into the engine, fire the engine up right away and go for a drive, without any warm up time and observe if there is a smoke cloud out the tail pipe at the point and time as has been observed, My contention is there wont be a smoke cloud, the engine will drive just fine with no issues Prop

Prop and the Blackhole Midget

Lawrence Just drive it mate, I had forgotten, not really forgotten more unremembered that you had tried different viscosity oils before. That new breather is the go, I can't see any smoke from here anymore so all is well Prop Um Prop, I'm lost for words lol willy

William Revit

Yup. Willy. I agree. :). Prop. Me too. Lost for words. lol. I didn't drill my Midget block. The factory left the hole there for the mechanical petrol pump. The casting on my two Sprite engines hasn't been drilled/knocked out. So I intend to complete the job that the factory didn't need to do, as the engine was going to use an SU electric fuel pump. Clearly it doesn't cause a weakness prolem. Have you ever seen a 1275 or 1098 block cracked at the mechanical pump hole (road use)? I'm still curious though. My Midget a late 1275 block. Why does it have a hole for a petrol pump? Hi Dave. Sounds reasonable. But why does that only happen to 'some' engines', and only after a rebuild? I looked and looked at my pressure relief valves and springs. Correct length, no signs of sticking/scuffing, and the seats are good. Plus are the holes are clear of obstructions. i think this will forever remain a mystery, unless someone with the right kit to properly test bed the engines comes along and solves it.

Lawrence Slater

Why the fuel pump blank? Good question. The only reason I can think of is that the block was used for something else which required a mechanical pump. The Marina, which was introduced in '71, had a mechanical pump, but other parts of the block were different. The Allegro used a mechanical pump, I believe, whereas its predecessor - the 11/1300 range used electric. They were transverse engines though, so I don't know if the basic block would have started out the same. Maybe BL were thinking of standardising fuel pumps across the board.

Dave O'Neill 2

Sorry It appeared in the photo you drilled the hole in the block just below center of the 2 carbs If its in the fuel pump blob, then your okay Here is a thought...maybe our engine that suck oil are correct and error free and the engines that dont suck are the ones that are defective If thats the case, they may have opposite oil flow issues in the summer or with oil viscosities far thinner then 20/50 Posting 540...this is a slow motion car wreck Prop

Prop and the Blackhole Midget

The new car dealer's answer --- "It's a feature not a fault" lol willy

William Revit

Juast letting you know that I still haven't sucked any oil at all, since doing the modification. But more than that, the engine goes so much better with the modification. I've even turned the mixture screws up. There must have been an amount of oil always being drawn up, even after the 'big' smoke ceased. I might even go so far as to say it's worth doing even if you don't get the obvious oil sucking. Especially to an engine that already has a drilling for the mechanical petrol pump, since it's such an easy mod to make.

Lawrence Slater

Watch out - 'Holy Thread Revival Batman!' Cheers Mike

M Wood

Ten minutes scrolling down just for that?

Alan Anstead

OOOOOOOOOOOOOOMMMMMMMMMMMMMMMMMMGGGGGGGGGGGGGGGGGG AAAAAAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHH Rob

MG Moneypit

Viton oil seals with a metallic cap cured oil sucking in the B. It is getting about 4,500 for each half quart. The machinist also installed the O-rings that came in the head set. I have been experimenting with this recently. Time to do the Midget. It is also blowing oil smoke when cold and needs a quart of oil every 1,000 miles. Doesn't drip though!

Glenn Mallory

Glenn, if your Midget is blowing oil smoke when cold for the same reason as the thread author's was then why not use his cure. To BL in their Technical Service Bulletin No. 72-A-4 - "2,400 miles or more per gallon (600 per qt.) is an acceptable consumption rate after the vehicle has completed at least 5,000 miles, and is widely accepted." (See attached PDF.) Now it doesn't say if it's USA or UK gallons but BL's accepted oil consumption and your 2,250 miles per USA pint and 500 miles a USA pint for the Midget both would be high to me as I use expensive oil and want to keep as much as possible in the engine, even if the rocker cover leaks. I did find there was less leakage when I made a better seal between the the dipstick and the tube it's held in.

Nigel Atkins

The PDF file is all gobble-de-gook. Too much character compression. Rob

MG Moneypit

Depends on the size and quality of the device you view them on, if you're using a portable device such as an i-can't phone, tablet or small laptop (must have skinny thighs) then it's to be expected. On more suitable (and reliable?) devices they can often be made out. Though I much prefer jpgs as I find (as a totally non-technical computer person) they can be resized much more easily to keep detail.

Nigel Atkins

This is how it looks on my desktop PC. Struggling, but I can guess at some of the words. Edit: Amazingly, it is slightly clearer as a jpg than it was as a PDF.

Dave O'Neill 2

That's exactly how it appears on my PC as well. I can get a few more words viewing at arms length strangely enough. Rob

MG Moneypit

I'm too tight to pay Adobe anything for their program to optimise the size for web viewing but a link to where I lifted it from, the T. Rex site - http://www.spridgetguru.com/TSBs/TSB_no72a4.pdf I supposed it helps that I know what it says but also my bad eyes and brain may make out more than good eyes and brains on the PDF on here. Yet I find some handwriting very difficult but my wife can read even most very poor handwriting (not as bad as mine though).

Nigel Atkins

How times have changed. 300 miles per pint was quite acceptable in those days!! But not the oil drops on the drive maybe? A friend of mine had a Volvo XC90 which he loved until it went in for a service. When he got it back, the next day there was a drip of oil on his drive. He contacted the main agents who did the service to be told it wasn't their fault. He pressed them further and he was told they had a recall due to fires and the fix was to remove the oil drip tray underneath that had a small chance of bursting into flames if the exhaust got too hot. After that he had a daily drip on his drive. Rob

MG Moneypit

I'm not sure things have changed that much, I think what I'd consider high oil loss/use still seems acceptable on modern cars to the dealership and manufacturer, I was very surprised when I last checked I thought the figures were from the 70 and 80s. One I looked up was a 17 year old Nissan, yes I know it's old but at least it's this century and millennium and it was surprising high. My wife's previous modern Vauxhall (own) diesel engine didn't surprise me as they always used to be loose engines.

Nigel Atkins

Just for Colin M - one of the infamous oil sucking threads revived (again) Cheers Mike

M Wood

Thanks Mike. I had considered reviving this thread but thought I'd hold off until I'd done a bit more investigation and experimentation. I'll be taking a close look at the PCV today. With the lid off and the engine running the diaphragm is fully sucked down but there is still very strong suction on the input port which doesn't seem right to me as I thought there to be virtually none. I will, however, go through this thread again to see what I can learn. I'm still only part way through re-reading the other huge oil sucking thread! Colin

C Mee

I feel a bit of an interloper in this venerable thread, and my concern isn't really oil sucking, rather the lack of it. I have the standard PCV valve and 1098 rocker cover with breather cap, and breathers from block side cover and redundant fuel pump point. As there was minimal suction at idle (by beer mat test) I just tried plugging the dipstick hole. Suction is a bit better, and the standard test of taking the filler cap off reveals a slight rise in revs, which I didn't get before. So the question is, how do I seal the dipstick on a 948 block? I have a bit of fuel hose round the stick but that only sits lightly on the block. Regarding intermittent oil smoke from exhaust, I had this but it was nothing to do with oil sucking. The head had a crack in the roof of the centre exhaust port, which only opened up when the head got really hot. It usually did it when idling after a quick run, because of heat dumping. Les

L B Rose

Les, have you tried splaying out the short return end so that it sticks out a bit and grips the dipstick a bit so holds the dipstick steadier in the tube to keep the seal more. And/or IIRC someone said before they have the dipstick tied or wired or sprung down, can't remember the details now (think it was a wire tie?).

Nigel Atkins

This thread was discussed between 14/09/2014 and 30/03/2021

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