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MG Midget and Sprite Technical Valve stem seal replacement BBS discussion at MG-Cars.net
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MG Midget and Sprite Technical - Valve stem seal replacement
| My rebuilt MKII 1098 (10CC-DA-H 36345) engine is burning oil. I believe the oil is entering the combustion chamber via the valve stem for these reasons: - Blue smoke is only occasionally visible during shifts and does not seem to be continuous. - Compression readings are: #1 – 175 #2 – 175 #3 – 175 #4 – 179. (Engine warm. All plugs removed. No oil added to cylinders. Air cleaners in place. Throttle closed. Maximum pressure reached.) - When examining the spark plugs only #3 is dark and oily. The others are tan and dry. - Using about one quart of 20W50 every 600 miles. The midget has been driven 1,800 miles since it was returned to service. I have read that the valve stem seals can be replaced in situ, but I don’t know the procedure. I assume the valve springs need to be compressed to remove the valve cotter circlip. The tool shown in the shop manual requires the head to be removed. How does one do this with the head in place? Inexpensive universal overhead valve spring compressor tools are sold at auto parts stores and tool suppliers (http://www.harborfreight.com/universal-overhead-valve-spring-compressor-60335.html). Does this type of tool work on the Midget? Does the entire rocker arm need to be removed to use this tool? I understand that the piston needs to be at top dead center so that the valve does not fall into the cylinder. I’ve also read in the archives that the later model “umbrella” type seals are better than the o-ring seals and only need to be installed on the intake valves. The engine was rebuilt by a respected foreign car mechanic who specialized in British vehicles. He received training at the British Leyland factory and has been in business for years, so I assume the rebuild was properly done. New valve guides were installed during the rebuild. He has since retired and closed shop which is why I am attempting to fix this myself if I can. Any words of wisdom will certainly be appreciated. Thanks.  |
| Paul Noeth |
| Paul It is difficult to replace seals with the head on (methods include feeding rope/cord into the cylinder to lie on the piston at TDC and stop the valve falling down. Personally, I would prefer to take the head off. It's not a complicated or long job and it would allow you to inspect all aspects of the head. It might even be quicker than fiddling about trying to do this for all four cylinders with the head on. The best valve seals are the Viton ones you can get from Minispares / Minimania. They fit any A-series engine. You don't give the engine spec. Do you by any chance have hi-lift rockers? I had some on my 1275 and they were pushing the valve retaining cap down onto the seals and mashing them up. If good seals were fitted and not subject to mechanical abuse such as that they should last for more than 1800 miles. |
| Chris Hasluck |
| Paul, There are spring compressors that grab the top and bottom of the spring and squeeze it down. Then you get some rope, pull the spark plugs, feed the rope into the cylinder through the spark plug hole leaving some out so that you can pull it back out, turn the engine by hand until it stops. The rope fills the gap in the combustion chamber holding the valve in place. Compress the spring, remove the little locking devices, remove the spring, replace the seal and as Haynes always says, replacement is the reverse of removal. The only difficulty you may have is getting at the retainers depending on the spring compressor. You may need a specialized tool called tweezers. |
| Martin Washington |
| Chris, the engine is a stock 1098. My thought is the seal on #3 was some how damaged and if it is possible to replace without removing the head, why not give it a try as a first go. Failing that, removing the head is next on the list. |
| Paul Noeth |
| Martin, is the tool you speak of similar to the picture in my first post? Have you done this yourself? Do the rocker arms need to be removed to make room for the tool? |
| Paul Noeth |
| Paul why not pull the head, as it gives you the chance to have a good look around at the bits you don't normally see. I've recently done mine and it's not difficult and doesn't take too long. Graham - '65 1098 MKll |
| Graham |
| Paul, The tool that I used is similar to the one from Harbor Freight. You do have to move the rocker arm. You don't have to remove it, just slide it to one side. Loosen the adjuster, remove the push rod and you can wiggle it clear of the valve. And yes, I have done it although it was a few years ago. |
| Martin Washington |
| Martin, I was hoping it could be done without removing the entire rocker assembly. Thanks for letting me know that it can be done that way. Graham, I've always thought it is best to try the simplest, easiest, most direct fix as a first go. If that doesn't work, then dig a bit deeper. It is true that the head is not that difficult to remove, but it is more work than removing the valve cover and popping on a new seal. I also enjoy seeing the internal bits that one does not usually see, but my lazy side always wins out. Besides that, something would have to be very obviously wrong for me to recognize it. The engine runs great (except for the oil use) and I don't like to mess with success. :) |
| Paul Noeth |
| I have replaced stem seals using the rope trick. Pretty simple and quick too. In my case I was compressing the springs to remove the valve collets with a lever under the rocker shaft. So the rope in the cylinder needed to be pretty tight to give something to lever against. But using the little spring compressor device that Paul showed in his first post would be even easier. The rope would only be there to stop the valve from dropping down into the cylinder when the collets are removed, so wouldn't have to be so tightly packed. Rotate the engine so the piston is about an inch or so down the bore. Feed the cord into the cylinder and then turn the engine a bit more so that the piston rises, squashing the cord against the valve heads to stop them dropping down. |
| Guy W |
| Paul, In my opinion, you are on the right track. You will be back on the road before the head pullers can have the head off, and you can fill the gas tank with the money you saved on a head set. Keep in mind that because of the taper fit between the valve keepers and the cap, they tend to be jammed in place. After you have the rope packed up into the valves (make sure you do this with both valves closed) put a socket or such onto the valve cap and give it a bit of a whack with a hammer to get it loose so your compressor does not have to break it loose. When you do this, keep in mind that with a harder hit, this is a common way to remove the valve cap and keepers. So, if you are not familiar with how hard to hit, start light and work up to it until you feel it give. You may also want to plug/cover the holes in the head so you won't have keepers dropping into the sump if you hit it too hard. Actually, covering the holes is not a bad idea regardless of how you go about it. Charley |
| C R Huff |
| Chris & Graham, Sorry if I sounded insulting when I grouped you into my "head pullers" term. Your advice was well reasoned and valid, I just think it is over cautious for an engine with only 1800 miles that has good compression. Please forgive me if I sounded rude. Paul, If you pull any push rods out of the engine, be careful not to pull the cam follower buckets out of place or it will be a pain to get them back in. Watch it with a flashlight and twist the push tube while you lift it. The oil can offer enough grip to pull the cam followers out with the push tubes. Charley |
| C R Huff |
| Charley, good info. That's the kind of knowledge one gains from experience, which without it always makes the job more difficult the first time than it should be. Thanks. Guy, I was going to skip the rope trick thinking that if the piston was at top dead center the valves wouldn't have far to go anyway. But after reading your post I've reconsidered. I have the perfect piece of soft and very flexible nylon rope and it is easy enough to put it into the cylinder and raise the piston so everything is tight. Plus, it makes a good cushion between the valves and piston should I need to put some downward pressure on the valve stem to get all the pieces back in place. Another question -- I am not sure which valves are intake or exhaust. Looking at the position of the manifolds and assuming the valves are in close proximity to each, counting from front to back, valves 1,4,5,8 are exhaust valves and 2,3,6,7 are intake. So the seal on cylinder 3 intake would be valve #6. Is that correct? |
| Paul Noeth |
| Paul, It is best not to skip the rope. I have done it with compressed air instead, but it is a bit more risky if you loose the pressure. You are correct to look at the manifolds to determine in from out. I can't quite rattle the numbers off for you, but I seem to recall that two of the three exhaust manifold attachments are at the extreme front and rear of the engine, meaning number 1 and 8 valves are ex. Therefore, 2 and 7 have to be intake. I believe the center port on the head is exhaust. If that is right, it means the two valves closest to center have to be exhaust. That only leaves two more, so they have to be in. Also, I am guessing you have a Haynes or such, and that should tell you. Charley |
| C R Huff |
| Paul, :Ages old debate- will you be putting seals on all of the valve stems, or just on the inlets? There are valid arguments for and against both policies. I favour seals on all 8 valves, but with a 'new' engine in standard spec (inc. Standard cam) just on the inlets is probably the way to go. |
| Guy W |
| Slightly off topic, but there is a tool available for the Ford CVH engine which allows you to compress the valve springs without removing the head. It simply bolts on in place of the rocker arm. You still need to stop the valves from falling out, though. http://www.burtonpower.com/ford-cvh-valve-spring-compressor-vs150.html  |
| Dave O'Neill 2 |
| My two pence worth Pull the head off and replace the head gasket not forgetting to dress off the mating faces. You may as well and it is not that difficult to do. Makes things much easier for valve removal. By the associated head gasket replacement, you could well improve matters elsewhere also. Replace all valve seals - again may as well as they are cheap enough. Ensure they are located properly. A bit of valve lapping would also be in order - again may as well considering the valves are out. Easy to do and worth it for the potential improvements associated with a better sealing of the valve. Consider replacing the valve springs themselves - again cheap enough. Some of the cheaper lever arm spring compressors are pants. Just not strong enough. Get a threaded type - far stronger and actually cheaper. Ultimately of course, get hold of a decent Metro head, bolt on, and enjoy the power! |
| Mark O |
| "Compression readings are: #1 – 175 #2 – 175 #3 – 175 #4 – 179. (Engine warm. All plugs removed. No oil added to cylinders. Air cleaners in place. Throttle closed. Maximum pressure reached.)" You should repeat with the throttle WIDE OPEN. As regards the rest, I agree. It's an unknown motor. I reckon the time you spend mucking about with rope, you could have had the head off for a proper look. I wouldn't go as far as to replace the whole valve train though, unless you see something obvious. They may not be the very best, but the standard rockers are by no means rubbish. Mine are all originals and I have no engine trouble at all. Same too with the springs, unless you find a broken one or exceptionally weak one. All depends on what you want the engine to do and how much money you want to spend vs save. |
| Lawrence Slater |
| Paul, When I did mine, I changed the seals but also fitted them on all the valve stems, but it sadly didn't cure it. After pulling the bottom end, it was discovered that three of the four cylinders had broken oil control rings in various pieces. I've got to stress that it was an engine of unknown life. All rings changed, cylinders deglazed and after reassembly all's well. '65 1098 MKll Good luck with whichever way you decide. |
| Graham |
| Valve stem oil seals on the inlets only - the exhaust stems need the lubrication and are only subject to outward pressure from the combustion chamber. Richard |
| Richard Wale |
| Maybe l have misunderstood but l got the impression from Paul's first post that the car has only done 1800 miles since the evengine was rebuilt by a mechanic. That's why l was advocating the minimalist intervention aproach. The compression figure are OK, and consistent. Doing them WOT is more accurate but if anything should increase the readings. |
| Guy W |
| Guy You perhaps assume the mechanic did a good job! Burning oil 1800 miles after an engine rebuild suggests otherwise. Personally I would also check out the valve guides/valve stem clearance for any undue wobble.... |
| Mark O |
| I have to agree with Chris, Graham, Lawrence and Mark. In your place Paul I'd have the head off, the valves out, guide clearances checked and the valves lightly re-lapped. Your first post mentions that there were new guides fitted during the rebuild, so it's reasonable to assume the stem-to-guide clearance is okay, but it's by no means certain. Therefore I'd very carefully inspect No.3 bore (and the others while they're handy) for any signs of scratches. A broken oil control ring as mentioned by Graham wouldn't necessarily affect the compression test in the way that compression rings would if damaged. Removing and reinstalling the head is not as big a task as it looks and it should come off fairly easily, since it's only been on 1800 miles. You could do the whole job in an afternoon, if it's only the valve stem seals. But have a good look at the manual first, especially for the correct sequence for slackening and tightening the studs. Best of luck, mate. Rod. |
| Greybeard |
| It was noted that compressed air could be used. Take an old spark plug with the glass part removed and weld it to an air hose connector. Screw in the plug adapter and connect to your air compressor. The constant supply of air will keep the valve in place if you decide to do only the seals. |
| J Bubela |
| J Bubela, I like that idea. I have some old plugs, air hose connector and a MIG welder. Not so much to hold the valves up, I think the rope will do that well, but to listen around the valve stems to see if one is passing air more than the others. I suppose they would hiss like the carbs and you could tell which seal is not working by listening when a particular valve is open. Or not... but it will be fun to play around with just to see. Dave, I like simple tools. I don't think this was offered so much as a suggestion but as a point of interest. If I understand how it works, I don't see how it could be used on the Midget. The rocker shaft brackets are too high and the tool would not reach the springs as I see it. Thanks to all for the comments. I have to order the seals and the car will be in use for the next couple of weekends. It may be towards the end of August before I try to change the seals from topside. If that does not help, then off comes the head after the driving season is over. Having said that, there is a little more to the story. (Sorry Prop, I hope this news doesn't send you into another conniption. ;) When I bought the car in 1972 it burned as much oil as gas. Exaggeration, but you get the drift. We paid $250 for the car if that is any indication of its condition. After driving it for a couple of years (and suffering jokes about being a mosquito fogger) I rebuilt the engine myself. I replaced the rings, etc. and had the head rebuilt by a local shop. After getting it back in service, the engine never quit burning oil. I drove it for 2000 miles or so and it was burning about a quart every 500 miles (sound familiar?). A leak in the hydraulic clutch line put the car out of service and I just parked it. For thirty-some odd years. I didn't do anything to it for storage, just parked it. Fast forward to the turn of the new millennium, we decided it was finally time to rebuild, lest we become too old and stiff to even get into the Midget. I went over the story with the mechanic who rebuilt the engine for a second time, and asked him to see what I might have done wrong. After the engine was torn down the mechanic said he could find nothing wrong. The rings were not damaged and were fitted correctly. The pistons and cylinders were in spec. He could see the cylinder walls had been properly honed. His only explanation for the oil burning was "sometimes the rings just don't seat." He installed Deves rings when he did the rebuild saying they are better quality than the standard replacements and that he has never had any problem with them. I used Royal Purple break-in oil for the first 500 miles and then switched to Kandall GT-1 10W50. I drove in an increasing spirited manner during the next 1,000 miles, but only occasionally broke 4,500 rpm. This is a street machine, not a race car, and that is how tried to break it in. If I were to bet, I would bet that the seals will not stop the oil burning and this winter the head will come off for a closer look. But the seals are worth a try and if they work, I won't mind at all losing that bet.  |
| Paul Noeth |
| Sorry, 20W50. |
| Paul Noeth |
| Paul, you are correct, hence the 'off topic' bit. It was a remarkably simple idea. The Ford CVH was a SOHC engine. There was no rocker shaft, as each rocker was mounted on its own stud. To compress the valve spring, it was simply a case of unbolting the rocker and fitting the tool in its place.  |
| Dave O'Neill 2 |
| Paul, If you put air pressure in the cylinder, and hear air leaking around the valve seal, that means the valves are leaking. And, if the valves are leaking, you would not likely hear it around the valve seals because all the air is going to rush out of the manifold. Charley |
| C R Huff |
| Paul, your last post much more interesting. Some good history there. I've heard people speak about new rings not seating before as well. If the new seals don't help there may be another explanation to consider......... Sorry to resurrect a grim spectre, but is it possible your engine is an "oil-sucker" like Lawrence's 1275 used to be? Can it be that oil is being drawn through a breather into the induction manifold and burnt off? I have to say I don't know the A series engine well, so it's speculation at best but I just wonder..... By the way you were correct about the disposition of the valves. From front to back it's exhaust, inlet, inlet, exhaust, exhaust inlet, inlet, exhaust. So No.1 inlet is the second from the front. No.2 inlet is the third. No.3 inlet is the sixth and No.4 inlet is the seventh. Very few inline fours vary from this layout. One exception was the Hillman Hunter and I once spent a full day trying to figure out why the hell the "rule of nine" wasn't working! Also.....what Charley said. Bit of a red herring I'm afraid. |
| Greybeard |
| Charley, the particular valve in question would have to be open as I mentioned. But I had not thought about the air flowing out the manifold. I suppose I could block off the manifold ports, but if I am going to that trouble I might as well just remove the head. Which I am not going to do... just yet. Greybeard, thanks for confirming the valve placement. I thought I had it right, but it is always good to check. Regarding the engine being an "oil-sucker" that may be the problem. I don't know how to evaluate that. The engine has a fitting on the intake manifold to which the PCV valve is attached with a rubber hose. Another hose runs from the PCV valve to the oil separator which comes off the timing chain cover. The diaphragm looks good and the PCV valve rattles when I shake it, but I don't know how to confirm it is, in fact, operating correctly. I will inspect the PCV valve and look for oil within. If the PCV valve is dry, I would guess that oil sucking would not be the cause. I'll let you know what I find.  |
| Paul Noeth |
| Ok, that was easy enough. There is oil in the hose between the oil separator and the PCV. There is oil pooled in the PCV intake (pic). There is oil inside the PCV. The diaphragm is soaked in oil. When I peer down into the intake manifold I can see it is wet and oily. I guess I have an "oil sucker", unless there is normally oil as described above. I'll research the archives for info on how to solve this. I hope this is where the oil is coming from and the valve stem seals and piston rings become a non-issue. If I have more questions about the oil separator, which I am sure I will, I'll start a new thread as we appear to be headed down another path. Thanks for the heads up on this one.  |
| Paul Noeth |
| Your oil separator should be attached to the forward tappet chest cover, not the timing cover, although it's difficult to see because of the heatshield. |
| Dave O'Neill 2 |
| Dave, you are correct. I just didn't look. That may be good news. If I have to remove the oil separator it looks that it will be a lot less work to remove the tappet chest cover than it would be to remove the timing cover. Thanks. |
| Paul Noeth |
| Paul, l think Dave's point is that for a 1098 engine, yours has the wrong timing chain cover. That sort is for a 1275, which uses a different arrangement. Yours is supposed to connect to the he tappet cover. |
| Guy W |
| No, the separator looks like the right one, due to the angle and location. If it was on the timing cover, it would be more towards the centreline of the engine. |
| Dave O'Neill 2 |
| Paul, with a pcv valve, if there is excess air ingress to the 'closed' system a lot of oil can be burnt. Some years ago I took the dipstick from a new build landrover engine to set the ignition and forgot to put it back....five minutes of 'running in' cruise on the rollers and the unit filled with oil smoke. Eventually realised problem and put dipstick back in...smoke cleared after a few more mins running. Try sealing any part which allows air to enter engine(not the carb intake!). We have found faulty pcv valves cause same problem. To be honest I blank off the pcv valves when I can and vent breather to atmosphere. A word of caution though, the scroll rear seal needs a slight negative pressure in the sump to prevent it leaking. We have used the Keith Calver rear oil seal conversion on the last half dozen Midgets we have worked on, it is well thought out and well made. Peter |
| Peter Burgess Tuning |
| I don't recall anyone ever reporting an oil sucking 1098. I think you may simply have a dodgy PCV valve. If it is, and all new ones really don't work properly either, then do you have pipes on the SU's to connect the hose from the tappet cover to? If not, then either get carbs that do, or you'll have to vent to air, and do as Peter says, and fit a rear oil seal if it drips out of the back with no pcv connected. But the PCV isn't only to prevent drips from the rear scroll. It's there to keep the oil cleaner, and to remove unwanted gasses and mositure from the crankcase too. |
| Lawrence Slater |
| Thanks Gentlemen. In reading through the archives I found that most, if not all, of the comments related to oil sucking referred to the 1275 engine. There is no doubt in my mind that there is oil going into the intake manifold through the PCV valve. But it does not fit the description of oil sucking that I've read about. Perhaps this is oil sniffing or something a bit less drastic. No clouds of blue smoke out the back. As I have mentioned, I only see smoke occasionally during shifts. I am not leaking very much oil, I see only an occasional drop now and then on the floor under the car. But the oil is going somewhere. I drove the car this weekend for 200 miles, much of it on a limited access highway at 70+ MPH. (Hit 77.2 according to the GPS track. The tach indicated a bit over 4,000 rpm in 5th gear. Rivergate conversion.) After pushing the engine hard for more than 3 hours, it consumed about 1/2 quart. Peter, your comment about the dipstick is interesting. Mine fits into a plastic tube that goes into the block. However it is loose and rattles around. If there is negative pressure in the crankcase this would definitely let air in. QUESTION: should this engine have a vented or non-vented oil filler cap? I don't see a vent hole in the top of the cap so I don't know how to tell for sure. (I can't see a vent hole in my gas cap either, but I've never heard air being drawn into the tank when removing the cap so I am reasonably sure it is vented.) Since I don't think it is the rings (fingers crossed) the oil may be entering the combustion chamber through the valve stems, the PCV valve or a combination of both. I've ordered both valve stem seals and a new gasket for the tappet cover. My ever-changing plan is now to: 1. Seal the dipstick temporarily (with tape) to see if that reduces oil consumption. If not then... 2. Remove the oil separator, clean it and see if that helps. 3. Next up I will replace the intake valve stem seals. 4. If no change, add exhaust stem seals. 5. If the oil burning continues, I will remove the head after the driving seasons ends and have it inspected and rebuilt if there is no evidence of broken rings or anything else amiss in the cylinders. 2a. If oil consumption is not reduced after cleaning the oil separator I may try to temporarily vent the engine to the atmosphere to be sure oil is not entering through the PCV system. However, I am not sure best way to do this. If I remove the PCV valve and cap off the manifold inlet is that all I need to do? Any crankcase pressure could then escape through hose on the top of the separator. I'll also put the hose end into some sort of container so that if oil is exiting through this route, I will be able to see it. Thanks to everyone for your help and suggestions while I try to figure this out. |
| Paul Noeth |
| Hi Paul I don't know if the engine should have vented cap or not. The simplest thing you can do is vent to atmosphere, seal poff the pcv valve and see what happens over a period of time. Peter |
| Peter Burgess Tuning |
| If it's got a rocker cover tube to the air filters, then no need for a vented oil filler cap, as far as know. |
| Lawrence Slater |
| I just looked in the latest issue of Practical Classics and, lo and behold, there is an article on how to fit valve seals without removing the head!! Serendipity! Chris |
| Chris Hasluck |
| ....and for further reading on the mysteries of the PCV Valve http://mgaguru.com/mgtech/engine/cv103.htm |
| M J Chapman |
| That's an interesting article MJ. If I read it right Paul should be able to verify the operation of the PCV by inducing the 'fault' conditions in the article. Removing the oil filler cap SHOULD give a fast, rough idle. Closing the oil-fill hole with a hand SHOULD give slower, rough idle. If that test sends the mixture and therefore idle speed back to where it was with the cap fitted, wouldn't that suggest the oil cap vent being blocked? I can't tell from the photo if it is a vented cap and I can't see a vent hose to the aircleaner. Again if I read it right, the restriction in the oil cap vent is crucial to limiting the airflow through the crankcase to a level the PCV can handle. Conversely if the crankcase is drawing air from somewhere else, like the dipstick hole as Peter suggested, this would give uncontrolled flow through the crankcase and cause the PCV to remain wide open. An unrestricted vent hose between the rockerbox and the aircleaner would presumably do the same. Would the increased airflow be enough to draw up oil from the separator? As to valve stem oil seal wear I seem to remember it usually manifests as a fair bit of smoke on start up, which mostly clears fairly quickly to at worst a light haze. Paul's description of seeing puffs of smoke on gearshifting seems to suggest to me that it's more pressure/vacuum related and the dirty No3 plug MIGHT only be because the PCV outlet appears in the photo to enter the induction manifold right next to No3 inlet port, so far as I can tell. Just some musings from a diesel mechanic! Come on, you A series Ninjas, what do you think? Does he really have to replace the seals at all? |
| Greybeard |
| I meant to say might a new vented oil cap for what - $15 maybe - fix the problem? |
| Greybeard |
| I think, Greybeard, that most of the A series officionados are keeping quiet for fear of setting off another terrifying mega-thread on the intricacies of crankcase ventilation and oil sucking! |
| Guy W |
| Haha Guy, that could be it! I have a 1500 so I can go where the angels fear to tread, in my ignorance! I still think from reading about it and having a good think that a new oil cap and a new push-fit bung for the dipstick might actually solve the problem. And being so easy I'd say worth a shot. What do you think? Probably need to fiddle with the carbs as well to correct the mixture once the crankcase ventilation is sorted out. |
| Greybeard |
| Nah, this can't be oil sucking, because the tappet covers don't fill completely with oil. Or do they? Queue shark music. Da-dum. Da-dum. Da-dum da-dum da-dum da-dum daaaaaaaa. lol. http://soundcloud.com/aamandacarp/jaws-theme-song |
| Lawrence Slater |
| Haha - all the way from Streatham with a double bass for one gag! Accepted it's not oil sucking in the conventional sense, but if it's coming from the separator is that affected by the relative heights of the tappet chest and the separator itself? I've learned a lot from this. I confess that I generally thought of the separator and PCV as basically a nanny-state driven emissions reduction measure, but it seems to be something much more interesting. So I now wonder if Peter Burgess has said the first thing I ever want to disagree with him about. If it maintains the negative crankcase pressure effectively and scavenges the blowby gasses and moisture, why would one want to get rid of it, in the absence of something else to do the same job? I thought the 'terrifying mega-thread' was good fun. I wish I'd paid more attention. |
| Greybeard |
| The breather/ extraction system is different on different versions of the A series engine. The early 850 (805cc?) engine was very low power and relatively low revving which only needed a passive vent to atmosphere. As the engine versions increased in power/ revs/ compression/ capacity the pressure build up in the crankcase progressively increased. The designers repeatedly redesigned the breather system to match the increasing need for greater extraction, partly to meet emission legislation but mainly to provide a PCV system to minimise oil loss through the rear crank "oil scroll", ( adding confusion here as PCV can mean either Positive Crankcase Ventilation or Pressure Control Valve, depending on the context!) The a 1098 has a different system using manifold suction controlled by a PCV. Whereas the later 1275 manages without a PCV as it uses the lower suction available upstream of the carb butterfly. Mixing components or design of different systems can give erratic or unexpected results! |
| Guy W |
| Close, Guy. The A30 had an 803cc engine, as did the Minor, following on from the 918cc side-valve engine. |
| Dave O'Neill 2 |
| Thanks Dave. I knew that the 850 wasn't the first, smallest capacity version, but wasn't confident in my memory which is why I put the 805 with a question mark, and in brackets. Accepting your reminder of it being 803cc! |
| Guy W |
| Thanks Guy. That reinforces what I've understood from my reading. I don't remember any of this gubbins from any of the A series engines I've had anything to do with. Minis, Austin 1100s/1300s and so on. Not that many of them TBH - I only ever fiddled with them when I had to. I've learned about dipstick tube sealing from certain big diesels. Some older types (older CATs for examples) can spit the dipstick out and throw the engine oil out after it. The old Arun class LifeBoat had two CAT 3408 engines and I heard of a case where one threw its dipstick out and started spraying the engine oil more-or-less straight into the inboard airfilter of the opposite engine. (The 3408 is a Vee engine). On the Severn class I work on there are 2 x 3412s, basically a bigger versions of the same engine, and we have restraining clips and springs to prevent the dipsticks coming out. If the oil gets out and into the intake of the other engine that's effectively an uncontrolled fuel supply, which in a diesel is 'Double-Plus-Ungood' as Orwell would say. Sorry about the digression into the wonderful world of diesels. In the case of Paul's 1098 all the history suggests that the problem is something really simple as the system as a whole seems to be very finely balanced. All it would take is a blocked vent or too much air getting into the crankcase and the PCV would flow way too much air. But I just don't know if that would be enough to draw the oil up from the separator. |
| Greybeard |
| Interesting discussion. I've just read through the MGAGuru article. I'll need to read it a couple more times to understand it all. A couple of points... 1) From everything I have read this problem is not "oil-sucking" in the classical sense as it relates to the 1275 engine. 2) There is no tube from the rocker cover to the air cleaners. See the photo Posted 07 August 2015 at 16:07:39 UK time. There is a tube from the oil separator to the PCV valve and another from the PCV valve to the intake manifold. There is no connection to the rocker cover. 3) The MGAGuru article says, "The flow volume of ventilation air going through the crankcase is determined by the vacuum level and the size of the inlet restrictor orifice." Where is this orifice? In the filler cap? I have temporarily sealed the dipstick with silicone repair tape. No air getting through there for now. I drove the car this evening and still saw an occasional puff of smoke during a shift. But certainly not every shift. I did not see any smoke on start up. While I have not driven it very far (20 miles), I don't think the lack of a positive dipstick seal is the problem. What does seem to cause the smoke is when I "over-run" the engine. (Or whatever it is called. This would be, for example, when taking your foot off the accelerator while the car is going down hill or coming to a stop by down-shifting.) After such an over-run, when I blip the throttle it will likely result in a puff of smoke, although not every time. But then when I take off like a banshee and wind the engine up there is no visible smoke. I seem to think that points to valve stem seals, but I'm speculating. And before I read the MGAGuru article, I remembered something about the oil filter cap and removing it causing a change in RPM. After throughly warming the engine, I stopped and removed the oil filler cap. The engine RPM increased from 1,000 to 1,200 RPM. However, the engine idled smoothly at both RPMs. When I put the cap back on, it dropped back to 1,000. I did not put my hand over the filler neck, but will try that tomorrow to see what happens. |
| Paul Noeth |
| How is the engine recieving air ? Non vented oil cap, and no vent from the rocker cover to the air filters...metered air has to enter engine from somewhere. To seal the plastic dip stick tube .... pull the plastic dip stick holder and match up O ring on the buttom of the plastic tube so it seats where the plastic meets the block, remark your dip stick the same thickness as the ORing My guess if the PCV is working correctly, the problem is the gause inside the oil seperator has gone bad, ( oil, rust and time are bad for this gause) the gause becomes a soild clunk and the oil vapor mist simple bypasses the gause and collects most likely in the pcv where it cools and reverts mack to a liquid instead of a gasous form The gause is nothing more then an industrial type of stainless steel pot and pan scrubber..non soapy version Im not sure about the 1098, but on the 1275 it looks simple but actually a zombi nightmare as most of the front of the engine has to come ... :-$ Prop |
| Prop and the Blackhole Midget |
| Hi Greybeard I suppose removal of system depends on capability of scroll to prevent oil loss when running. Personally I prefer to keep engine fumes away from engine as it is unwanted dilution/contamination of air/fuel. Vent to atmosphere for road use and to a catch tank for race use. Fit an oil seal conversion and all is good. Some of the problem I have is if the engine I build subsequently leaks at the scroll it is my fault even if scroll crap to start with. For this reason I fit a rear seal conversion. This allows us to remove pcv valve with impunity so no worries about ingress of air to system allowing extra oil etc to be drawn into pcv valve. My experience of pcv valves on all types of engines has not been good. Something waiting to go wrong on A and B series if that diaphragm fails, who knows how good the quality of replacement ones are, maybe not quite oil proof? Peter |
| Peter Burgess Tuning |
| This is the stainless steel pot scrubber that is the gause inside the oil seperator You can find them at ace hardware, true value, and probably home D., Lowels, or menards http://m.ebay.com/itm/2-x-SuperSteel-Pot-Scrubbers-Stainless-Steel-Sponge-Commercial-Grade-NEW-/221228439274?nav=SEARCH Prop |
| Prop and the Blackhole Midget |
| Wow, you pressed submit button 6 seconds after me Prop :) Peter |
| Peter Burgess Tuning |
| Not me peter... but the network is barely funtional tonight Btw... I got the fuel pump finally working, so now im trying to find a decent day to tune in the carbs Prop |
| Prop and the Blackhole Midget |
| Peter... Just curious ... if you vent to atmospher how do you create the negitive vacume in the engine... I can understand having the conversion seal , but on the rivergate kit, the rear seal conversion is okay and does the job, under normal conditions ... id qusetion it without vacume in the engine but any more then avg blow by and the rivergate rear seal conversion becomes a pisser. there are better designed kits out there. Prop |
| Prop and the Blackhole Midget |
| Paul, The PCV system is a pretty finely tuned arrangement which balances two rather differing functions that it tries to do at the same time. On the one hand it needs to draw lots of air through to get rid of the noxious crankcase fumes and for this you would need free air entry plus good suction. But at the same time it seeks to minimise oil leakage from the rear scroll seal. For this it has to create a negative pressure in the crankcase so needs suction and a restriction on the amount of air entering the system. Anyway, apart from saying don't mess with it I think this is all a red herring and that that the PCV extraction system on your car is probably just fine as it is. I would leave well alone. Your listed symptoms are, as you say, absolutely classic for an engine which is drawing oil down the inlet valve stems. This happens on "over-run" when the fast spinning engine is providing lots of suction, and the throttle valve is suddenly closed. So the suction pulls air - and oil - down the valve stem instead. If the valve guides are worn or oversized then more oil gets in and you get a bigger puff of blue. I can think of 3 culprits that may worsen the situation. First, heads that have been modified for unleaded may have valve guides intentionally reamed out to give greater clearance because of the lack of lead lubricant in the fuel. But strictly, this is only necessary on the hotter running exhaust valves and inlet valve clearances don't need to be modified. But perhaps yours have been done anyway. Second is worn, cracked or dried up valve stem seals, just as you first thought. Worsened if the valve guides are worn or oversized as well. If the engine stood unused for a while the rubber seals can dry out and crack so this could well be your problem even with a low mileage engine. An easy fix, just as you first planned and this would be the first thing I would try. Last - if the oil delivery to the rocker cover chamber is excessive this can flood the top of the head with excess oil so that the valve stems are awash. The seals aren't really seals but more of a sort of oil wiper that stops too much oil collecting on the valve stem. But if the area is flooded this doesn't work. Too much oil flow there is caused by worn rocker shaft and/ or worn rocker bushes. The wear simply provides too much clearance for oil to flow out around the bushes, especially at high revs. Pull the rockers to one side a bit and check the underside of the rocker shaft with your fingernail. If there is wear, it may be sufficient just to replace the shaft and they are relatively cheap. And you still don't need to remove the head! |
| Guy W |
| Thank you Peter. Another little bit of understanding! No offence intended BTW - I know you know what you're doing just didn't quite get my head around it! Cheers. Rod. |
| Greybeard |
| Without adequate crankcase ventilation, --- "Impurities such as water vapour and acids (by products of combustion) will build up and contaminate the oil causing sludging and increased engine wear." A dog isn't only for xmas, it's to keep you engine clean too. ;). Irrespective of polluting the road surface and environment, a draught tube isn't as effective as properly applied suction. Does it really ruin/degrade the fuel if the system is working properly? I've read that some race engines run at a quite high level of -ve crankcase pressure, as a means of boosting hp. Maybe the best system is the exhaust manifold connection. Aside from that, I agree with Guy. Sounds like oil drawn down the valve stems on the overrun. As soon as you open the throttle again, the sucked in oil is burnt with a puff or more of smoke. But, New valve guides only 8000 miles ago. I would assume he also used new seals too. Did he use new valves though? Maybe one or 2 have too much stem wear. You could still have a leaky head gasket. I'd still pull the head, rather than use the indian rope trick. |
| Lawrence Slater |
| I never thought you were 'calling' me Mr Greybeard :) Prop, The Keith Calver seal works well with 1275 engines. I assume it can be fitted to the small bore engines but would have to clarify Lawrence, don't some of the race ones have a pump and some of them an ex system extraction and thus bypass the important engine internals twixt carb and piston? Paul, favourite is to fit the o ring style stem seals incorrectly. Top hat ones may be better. Peter |
| Peter Burgess Tuning |
| Peter I'm intrigued by the Keith Calver oil seal you refer to Is it the same as the Peter May seal I've been happily using for several years? It took me some time to get it lined up and mounted properly and I have had to replace the actual seal once I thought the new seal would cost an arm, leg and possibly several other items of bodily parts Had my ghast completely flabbered to get the new one to fit in the carrier for almost pennies I'd like to see if the Calver one is easier to set up, but feel it may be near enough the same As for looking it up on Keith's website, wow that isnt an easy search item at all |
| Bill sdgpM |
| I've ordered both the o-ring and later 1275 style seals. I've read the 1275 seals are better but having never installed either I ordered the o-rings in case the others did not fit. They should be here in a couple of days but I will not have a chance to install them until sometime next week. I will also take off the oil separator to clean and inspect it at the same time. I repeated the test removing the oil filler cap. As before the engine idle RPM increased. When I put my hand over the oil filler port the RPM decreased just a slight bit from normal. In both cases the engine idled as smoothly as when the cap is on. FWIW, I did figure out how to determine if the cap is vented. Remove the cap, wipe it clean, put your lips around the hole in the bottom and blow. Air passed through the cap and I could feel where it was coming out. See pic. The vent intake is hard to see unless you know where to look and have good light. While I cannot explain the oil in the PCV valve, the venting appears to be okay. I hope when I clean the oil separator the oil going into the PCV valve will be reduced or eliminated. I still feel the valve stem seals will prove to be the problem.  |
| Paul Noeth |
| Paul, when you do take the rocker cover off to do the seals, do check for wear in the rocker shaft. It does make a difference - even good valve stem seals fail to work when the guide tops are submerged in oil! |
| Guy W |
| Guy, This is a new engine with only 1800 miles on the clock Id agree with your premise if the engine was old or had high milage As is, I can only support your thoughts that its a valve seal if the seal was damaged during installation, the wrong seal, or manufacture defect (8 year old china girl needs a butt beating for slacking off at the china factory... completely irresponsible) Unless the seal is damaged or installed incorrectly .. I dont its the seal, I think its an evac issue Good news ... it will be easy to determin as we know its the intake Valve on #3 cly Btw... my concern in not pulling the head, and just removing the rockers, ... your still pulling 5 of 9 cly head studs, I just dont see that being a good thing, id imagine a new head gssket is in your near future if you just pull the 5 along the manfold side...just my personal opinion...id never be that lucky to get it resealed and retorqued . In fact wouldnt you have to remove the torque on all 9 cly head studs to retorque the 9 studs in proper sequence ? Prop |
| Prop and the Blackhole Midget |
| Hi Bill This is what Keith says.... CST3002 In-line A-series rear main seal kit instructions. Having tried all manner of methods to prevent oil leakage from the rear main of the in-line A-series engines, including the seal kits already on the market, I decided they were all a lost cause. Nothing worked well for any period of time on anything other than completely standard engines, and certainly not performance-orientated engines. I looked at some complex solutions that would make the kit very expensive. I wanted a solution that was effective and didn't cost the earth. I had various design ideas, but needed the help of experts in the seal arena, so enlisted the help of Race Tec, renowned for their work, and specialising in motor sport. Dealing with one of their tech design men and getting a handle on what they could do with seal manufacture, we soon came up with this design. It was thoroughly tested on their in-house jigs before I tested them in 'real life' fitted to engines first on an engine dyno, then in cars on the track. I then enlisted help from various A-series colleagues to test them in various formulae. The results were out-standing. To be able to install this kit, the rear main cap needs the original oil-catcher section machining off so that the rear face is flush with the rear block face. This needs to be done as accurately as possible to ensure the seal is held square-on to the relevant sealing faces. These are the rear face of the oil thrower and the flat journal surface between the end of the scroll and the flywheel boss. An accurate measurement taken from the rear edge outside diameter of the main cap locating dowel holes and rear block face is generally sufficient, but having the block on hand means it can be done with 100% accuracy. Once the cap is machined flat, the five seal carrier retaining screw holes need to be drilled and tapped. This can be done from the drawing supplied, or from very careful positioning of the carrier on the cap and spotting through the holes. If using the latter method take extreme care to get the carrier piece in the correct position in alignment with the carrier that fits to the block. I can have the main cap machined for any customer, providing they can supply me with an accurate measurement referenced from the main cap dowel as outlined earlier. Because both areas the seal lip will be running on are not generally precision machined/ground, some attention to smoothing these areas as much as is feasible will help seal longevity. Assembling the seal to the crank and then fitting the carrier pieces is straight forward. The seal is split to allow it to fit easily over the flywheel boss. It is fitted with the 'open' side of the seal facing the block. Fit with the split uppermost. Apply a small amount of sealant to the ends of the seal, and also to the inside faces of the carriers and carriers to block/cap faces, then assemble the main cap seal carrier to the cap first, leaving it a little loose, then the upper seal carrier to the block. Take care in ensuring the seal is as centred as possible (it sort of does this naturally - but rotating the crank helps further) before fully tightening the carrier retaining screws. |
| Peter Burgess Tuning |
| PDF of rear main cap mods. Finicky but the seal is good and looks right too. http://www.peter-burgess.com/PDF/KCSeal.pdf Peter |
| Peter Burgess Tuning |
| Peter, Do you have a link for kieth C. kit, I cant find it ... your description is very interesting, I have to say, just from my own experiance, is it really the scroll seal thsts the issue or is it the birds eye lip, that bolts on the top of the crank shaft section... mine was really rough and ragged, when I sanded it down flat and took all.the day light out around the edges, I think that had alot to do with why the engine no longer leakes... I think thats a big area for letting additional air into the engine Agian ive only got experiance with my engine... but that was a big gap that didnt get.much sealing from the gssket Prop |
| Prop and the Blackhole Midget |
| Sorry... birds eye = eye brow piece, the half circle piece that fits above the crank shaft on the block Prop |
| Prop and the Blackhole Midget |
| Prop,I don't think you need to undo any of the cylinder head fastenings to check for rockershaft wear. I think if you back off the adjusters with the valves closed and push the rocker out of position a little way along the shaft you should be able to detect significant wear as a kind of little ridge on the underside of the shaft. Or do what I did to find the wear on my 1500s shaft and/or rocker bores. If there is any movement up-and-down detectable when the rocker is unloaded and loose there is wear present. It doesn't need to be much wear. It can be hard to be sure of it. In my engine's case it took a sensitive stethescope to locate it positively, but it's there. A series Ninjas please correct me if this is wrong. Cheers. (I wonder if as a bodge I could just turn the shaft around 180 degrees so the worn section is at the top. That wouldn't address any wear in the rocker bore, but it might quieten things down for a while). |
| Greybeard |
| Peter, that's a vry illuminating post. Don't give away ALL your knowledge Mr B - that's no way to run a business :-) |
| Greybeard |
| Prop, No need for me to argue with you about this, as time will eventually tell. ;-) But my thinking is: A: Valve stem seals do deteriorate with time, not just with mileage. My understanding is that although it has only done 1800 miles. the engine rebuild was done around "the turn of the millenium" so the car has stood unused for quite a good period of time. The rubber valve seals tend to harden and crack with time, not just with mileage. And B: Although the engine has been rebuilt, the rocker shaft and rocker bushes are often ignored on the basis that they continue to work perfectly well. But, if there is wear then the rocker shaft will definitely be pissing oil out into the rocker chamber and it will pool on top of the head around the top of valve guides. Checking is as Greybeard describes, and doesn't involve any dismantling other than removal of the rocker cover. |
| Guy W |
| Hmmm, guy I dont think we are arguing/debating, just searching for clarity on our interpetation of what is being posted Guy... I think we are some what on the same page but I think the most recent engine rebuild was just recently not the turn of the millennia... 2000 if it was 15 years ago almost 16 years, then it might well be worth doing another rebuild, as im sure the valve seals are just the beginning of his problem...im thinking all new seals plus anything rubber or plastic has to be replaced As to the rockershaft... we have a miscommunication there, I agree with test and measure for wear, but thats not "Wear" im comming from my point was the rocker shaft has to be removed to replace the valve stem seal . Can the rocker its self bemoved by itself to the side withOUT removing the cly head stud? Im Not conjectering, I truely do not know if thats possiable, ive always assumed the cly head studs must be removed to remove the rocker assemble to gain access to the valves. Prop |
| Prop and the Blackhole Midget |
| To clear up a couple of points... the engine was rebuilt in December, 2002. It was stored in a controlled environment, never above 90F degrees or below 40F degrees. The crankcase was filled with straight 20w oil and the engine turned over at least every 6 months with the starter. Each time the plugs were removed and a small amount of oil added to each cylinder. The engine was cranked until oil pressure (about 30psi) registered on the gauge. Not that I mind, but how did the discussion turn to rear seals? Easy enough to get side-tracked but that is not an issue with this engine. It has a 5-speed Rivergate conversion. Best thing I could have done, it is awfully nice on the highway. I cannot imagine driving any distance in 4th on the Interstate. The conversion has the rear seal option, but it is not standard. The outside diameter of the flange on the end of the crankshaft was never machined at the factory. Consequently, the standard 3" seal with the Rivergate kit did not fit. The folks at Rivergate had never encountered this before. We had an automotive machine shop turn the flange down to 3-1/4" and fit the proper size lip seal. From that, we know the sealing surface of the flange was good and to date the rear seal is not leaking. For now, I am waiting for the parts and next week to roll around when I will have time to look at the seals. When I have the cover off I will definitely look at the rocker shaft fit. Thanks for the heads up on that. |
| Paul Noeth |
| When you have the rockerbox off Paul you might like to look at another thread 'Valve cover and clutch'. It contains Prop's method of resealing the cork gasket. I've used it since he told me about it last year and FWIW it works well. Best of British Mate. Let us know please how you get on. |
| Greybeard |
| Greybeard... D'Oh!! I was looking through the archives for 'Valve cover and clutch' and could not find it. Then I saw it in the active threads after I had given up looking for it. I've used a gasket compound to set the cork into the valve cover. I put a smear of oil on the block before setting the cover and have had it off several times without damaging it. When it goes back on I'll try smearing some lithium grease on the cork and see how that goes. No leaks so far. I am careful not to over tighten the hold down bolts. |
| Paul Noeth |
| Paul, If this hasnt been run except for 1800 miles for the past 15 years, I have to agree with guy on this one In fact I think your going to be money and time ahead to pull the engine and replace all the gaskets, seals, rubber and plastic pieces if you dont, your going to be chasing your tail with one leak after another Mine has sat about 8 months, and im tracking down one problem after another... these cars HAVE to be run on a constant basis of they just suffer Just a tip... if your replacing valve seals... do them all, otherwise you will be repeating this over and over. Prop |
| Prop and the Blackhole Midget |
| Hi Guy Spot on with the excess oil from worn rockershafts. We have our guides and head work called all the names under the sun many years ago but the culprit was a worn out rocker assembly filling the rocker cover! For this reason we fit all eight top hat seals these days. Transverse engines seem to struggle more with oil down guides from excess oil above head, we have no logic to this. Sometimes ex valves on tuned 1275 can nip in with oil seals. If this happens we remove the seals! Peter |
| Peter Burgess Tuning |
| You know what? - having looked closely at the Photos Paul has posted I would be surprised if worn parts were put back on this engine. It looks immaculate! Not just externally but even noticing that none of the head nuts or rocker lock nuts are showing any signs of burring or damage. The whole thing is put together really well. I do stand by my suggestion of checking the rocker shaft for wear or scoring as that will cause oil excess on the head (thanks for the endorsement Peter!). But given the state of the engine, I would be surprised. But now, looking back closely at Paul's photo of the valve springs / rockers etc - posted 6 August 20.05 - something does look odd. Its not very clear but the way the light is catching it looks like the valve stem O - ring seals are fitted around the split collets, immediately below the retaining spring clip. Surely they should be lower down, below the collet and just on the valve stem? Maybe its a trick of the light, but the more I look at it, the more it looks that way. Are these the seals, or something else? Is that normal on a 1098? I don't think so. In fact the one on the right of the photo (inlet valve cyl #2?) looks like the O - ring seal is fitted on the collet, but has split or bulged out and the end is poking up. Perhaps I am going doo-lally and imagining things! |
| Guy W |
| Paul, Going back to the some earlier comments on the PCV etc. Your engine has the PCV, which means that the crankcase ventilation system should have an oil separator on the front tappet cover, a hose from this to the PCV and a 'vented' oil filler cap. There must be no vent from the rocker cover. The ventilation system works by drawing filtered air in through the filler cap, down through the crankcase, with the fumes passing through the oil separator and into the inlet manifold, via the PCV - I would expect to see a witness of oil in the entry to the PCV, but not floods of it! The earlier engines, without the PCV, had a hose from the rocker cover to the air filter, an open 'draft tube' down from the front tappet cover and a 'non-vented' filler cap. The intention is that when the car is moving air is drawn in from the air filter, through the crankcase and the fumes pass out through the draft tube. Likely to cause drips from the draft tube, and with tighter emissions legislation, it was replaced with the closed circuit PCV system. Richard |
| Richard Wale |
| Guy With the 'old' style collets and valves there is a space at the bottom of the collets when fitted to the valve groove to trap the oil seal and squeeze it against the valve cap tapered sides to seal the cap. Peter |
| Peter Burgess Tuning |
| Prop asked a good question there. "Can the rocker its self bemoved by itself to the side withOUT removing the cly head stud?" I think it probably can, based on Paul's photo from 6th August. It looks to me like each rocker could slide along towards it's neighbour far enough, maybe using a cable tie or something to hold it out of the way. I never thought of that. |
| Greybeard |
| If, IF, - those ARE the o-ring seals visible in the picture that Guy referred to, --- Posted 06 August 2015 at 20:05:56 UK time -- , then it looks very much to me, like they are fitted in the wrong place. Here's how they SHOULD be fitted. But even if they are fitted properly, surely the reason BMC went the top hat route, was because an o-ring at the top of the valve stem, isn't much good at preventing oil running down the guide BELOW the o-ring. And if you want to fit the later top hat seals, you'll need grooved guides. As for the engine being built well, again, if those are the o-rings fitted in the wrong place, what else did the builder do wrong? Pull the head off and have a decent look. Just another thought though. With only 1800 miles on it, that engine is barely starting to run in if it was rebored. The rings(oil control) may not yet be sealing as effectively as they will when it is run in.  |
| Lawrence Slater |
| See here. Maybe the case is sol-ved, as inspector clouseau would say.  |
| Lawrence Slater |
| And that's just what this thread needs. A bit of sellers. http://www.youtube.com/watch?v=FfPsULW-wYc http://www.youtube.com/watch?v=1mbUdsQfSq0 |
| Lawrence Slater |
| Peter, with the O - rings fitted in the groove below the collets as you describe, they shouldn't be visible from the top unlike what l am seeing in the photo. These look to me like an O - ring that is fitted above the spring cap and around the collets. I know that there were several different arrangements over the years, but these look wrong. And then of course there is what appears to be a damaged one on cyl #2. There is another difference in that the earlier spring caps are dished so oil might tend to collect towards the centre. Unlike the flat topped caps in Lawrence's photo which are the 1275 variety. I will be interested to hear from Paul when he has had a chance to take a closer look. |
| Guy W |
| Good eyes guy I think you have a valid point Prop  |
| Prop and the Blackhole Midget |
| Is that a split washer under the bolt that secures the rocker pedestal Prop |
| Prop and the Blackhole Midget |
| Peter thank you very much for that very illuminating posting As I have been using Peter M's seal for ages, but have had to replace one seal unit already Keith's solution makes great sense I wonder whether to get one of those for next engine out time... maybe when I get you to tickle my Metro head probably next year Hmm Hops off thinking out loud... Thanks again |
| Bill sdgpM |
| Where would we be without dreams Bill? Peter |
| Peter Burgess Tuning |
| I think you guys are off base about the seals being on top. I've tried to take a better photo. While things are still not perfectly clear, I can see the end of the valve stem, the keepers, the clip which holds them and the top spring retainer (collet?). I cannot see any seals. Lawrence Slater's illustration from above shows how the parts are assembled and from what I see looking at the valves, all seems to be in order. I am assuming I will have to remove the springs and associated hardware to see the seals. Maybe after disassembling the valve springs I will be able to understand how the seals work. If I remember right, the valve guides are supposed to stick above the surface of the head by only a small amount. From the illustration it looks like the seals are at the top of the valve stem. If that is true how do the seals stop oil from going down the valve guides? When I took the valve cover off to take the photo, the depressions in which the valve springs sit were filled with oil. I'm assuming (again) that the oil will drain down the passages through which the push rods run. Isn't it normal that oil will always be pooled in the depression around the bottom of the valve springs? Are the valve guides supposed to stick above the pooled oil? (Which, in fact they may, I just can't see what is going on until I disassemble the springs.)  |
| Paul Noeth |
| Does anyone know if there is only one style of vented cap? In other words, are some made to introduce more air than others? I think I remember seeing some that were vented down the center with a filter in the inlet. Although it would be fiddly, I wonder if a rocker shaft can be pulled out the front after slacking all the adjusters. Then you would not need to slack the head bolts. In the photos, I am surprised that the shaft does not look fresher if it was new, but it is a bit hard to think it would not be new since they are known to wear out frequently. Do you know if the diaphragm in the PCV is good? I had that style on a Saab 99 and when it failed I opened the cap and threw one of those light weight rubber gloves over it, and replace the cover. Rod, I know what you mean about throwing hot motor oil down the wide open intake of a diesel. I had a 350 Cummins in a cab over Pete blow the turbo seals and run away. It was quite exciting while it burned 8 of the 11 gallons of available crankcase oil. I tried to stall it by easing out on the clutch in 13th gear, and it just instantly twisted the drive shaft tube out of it. And, some of the oil was spraying outside of the engine, so it was also on fire. Charley |
| C R Huff |
| Paul, OK, sorry about setting off that particular hare! In the earlier photo I convinced myself that I could see O - rings around the collets, above the spring caps. Especially as the one to the right of the photo seemed to be distorted just as rubber would when squeezed into the wrong place! Others just believed me, which is always dangerous! Having disposed of that, you raise the question about how the seals work in their designed place. Yes the guide ends extend up above the surface of the head. The O ring fits in the groove below the collets and seals to the underside of the spring caps, preventing oil from draining down from above. But they don't prevent oil from splashing onto the exposed stem below that. If they were pushed down to touch the top of the guide they would immediately be displaced upwards anyway, the first time the valve opens. This design was replaced with the introduction of the "Top Hat" seals on later engines, where the seal fits onto the top of the valve guide, and the valve stem slides up and down through the seal. I cannot see any reason why they couldn't be fitted to the earlier style either as an alternative or as an addition to the O rings. The flooding that I described from worn rocker shafts is sufficient to overwhelm the drainage holes in the head such that the oil pools on the head to a depth above the tops of the guides. Its surprising how fast oil is pumped out through the worn rocker bushes! It's worth checking for as its so easy to do, but as I said earlier your engine does look well assembled and I would be surprised if this was neglected when it was rebuilt. |
| Guy W |
| "Others just believed me, which is always dangerous!" Not so Guy. I didn't. That's why I used the word "if" with emphasis, thrice in my post. ;). I also added that the top hat seals which came later are more efficient, and that they CAN'T be used effectively unless you have the correct valve guides with the groove too. If you don't have the guides with grooves, the top hats will simply work there way off the guides and you be back where you started. Charley. We had a long discussion about the vented filler cap in various engine breather threads. There's only one plastic style and it vents in through the sides as in the picture earlier, and underneath there is a small hole that allows air into the rocker cover. The 1275 and the 1098 both have the same part number for the oil filler cap. But it's irrelevent anyway as this isn't an oil sucking issue, -- unless the PCV valve is malfuntioning, and even then there isn't a large pool of oil to suck up. Quoting Paul. "Fast forward to the turn of the new millennium, we decided it was finally time to rebuild, lest we become too old and stiff to even get into the Midget. I went over the story with the mechanic who rebuilt the engine for a second time, and asked him to see what I might have done wrong. After the engine was torn down the mechanic said he could find nothing wrong. The rings were not damaged and were fitted correctly. The pistons and cylinders were in spec. He could see the cylinder walls had been properly honed. His only explanation for the oil burning was "sometimes the rings just don't seat." He installed Deves rings when he did the rebuild saying they are better quality than the standard replacements and that he has never had any problem with them. I used Royal Purple break-in oil for the first 500 miles and then switched to Kandall GT-1 10W50. I drove in an increasing spirited manner during the next 1,000 miles, but only occasionally broke 4,500 rpm. This is a street machine, not a race car, and that is how tried to break it in." --- Pauls quot ends. Like I said, it may well be that the thing ISN'T run properly yet. BUT, we know it WASN'T rebored, only re-ringed, twice. You may have ovalled bores. Just because you can see honing marks, doesn't mean the rings are going to seal properly all the way down. Paul. As an experiment. Remove and clean the spark plugs. Disconnect the hose from the PCV valve, and hang it over the side into a tin to catch any oil that may drip from it. Block the hole in the inlet manifold, and go for a long drive. Get the engine nice and hot. Give it some welly and plenty of closed throttle deceleration. Tell us if you see oil smoke? Look at the colour of the plugs. Report back. All this guess work is a bit pointless. :). |
| Lawrence Slater |
| If there is excess oil on top of the head from worn rocker gear, which wouldn't surprise me a bit, that's not the only problem. The evidence is in the the PCV inlet and outlet and the wet oily induction manifold. Something is definitely awry there. Lawrence's suggestion of diverting that into a can or whatever so that it's not entering the induction would be a good way to find out if oil is getting in from somewhere else at the same time i.e. down the valveguides, but it still doesn't tell you why it's going through the PCV. I'm not sure if the rocker shaft can be drawn out with the head in situ as Charley suggests, but I think it's quite likely. There are some bits in the way though - heater box and battery in one direction, fan, radiator and cowl and probably thermostat housing in the other. On balance, if it were my engine, I think I'd prefer to lift the head and take the opportunity to have a look at other stuff while it was handy. Blimey Charley, that was a white-knuckle ride with the runaway. I've never seen it happen thankfully and I don't want to, but I have seen the grisly aftermath. It's why we have air stranglers as well as fuel shutoffs on our CATs. |
| Greybeard |
| Lawrence, The Minispares website show the following types of cap for the rocker cover: GFE6003 - vented 12A402 - non vented GFE6007 - late Mini / Metro ref http://www.minispares.com/search/classic/rocker%20cover%20cap.aspx |
| Doug Plumb |
| If the front rocker post has the correct locking tab under the 2 nuts to hold the rocker shaft locking screw in place then you would have to remove at least one cylinder head nut and rocker pedestal nut before the rocker shaft could be withdrawn. |
| David Billington |
| Ah yes, David. I see what you mean. Thanks. |
| Greybeard |
| Yes Lawrence, I did notice you were hedging your bets with lots of capitalised "IF"s ! ;-) My valve guides have been replaced when I had the head (MG Metro) "deleaded". The guide clearance is greater than standard on the exhaust valves. The guides don't have a groove around the top and the top hat style seals sit happily in position and certainly hadn't shown any tendency to work their way off when I last looked. If they did, then I might have tried a blob of adhesive of some sort on the lip of the guide. But I don't think it necessary. The symptom - puff of oil smoke on he overrun - is very indicative of oil being sucked into the chambers via the valve guides. If the problem was with the bores then the blue would be worst on acceleration and high revs, not on overrun and falling revs. |
| Guy W |
| Paul wrote.... Paul Noeth, Indiana, USA - I think you guys are off base about the seals being on top. Paul, (In our minds) We are professionals here, please dont confuse the thought process of our heard mentality with your (GUESSING) ... we will tell you whats wrong with your engine when we have fully exhausted all avenues of debate...please check back when this thread is at least 300 postings. We know what se are talking about. Now guys... what about brake drag, if the E. Brake was slightly engaged it could create extra work on the engine causing the flow of oil to slow down and pooling more at the top...anyone back me up on that ? HaHaHa Amatures ! ... Phiff, what would planet earth do with out us and our knowledge of all things midget.... HaHaHa Prop |
| Prop and the Blackhole Midget |
| From Prop's earlier post: >>My guess if the PCV is working correctly, the problem is the gause inside the oil seperator has gone bad, ( oil, rust and time are bad for this gause)>> Then from one of mine: >>If there is excess oil on top of the head from worn rocker gear, which wouldn't surprise me a bit, that's not the only problem. The evidence is in the the PCV inlet and outlet and the wet oily induction manifold. Something is definitely awry there.>> There's a good clue there. Prop may well be right that the gauze is choked and not allowing the separator to drain. Well - it's a candidate and an easy thing to trace. Prop - be serious. I'm not an armature. I'm an ammeter. Haha. |
| Greybeard |
| Some day when I grow up I want to be a volt meter Haha Grey, thats where im leaning also, a clogged up petrified gauze inside the oil seperator or a worn out pvc valve Prop |
| Prop and the Blackhole Midget |
| Today I vented the crankcase to the atmosphere. When I removed the PCV valve there was oil pooled in the intake and around the poppet in the bottom of the housing. The hose leading to the PCV valve and the diaphragm were wet with oil. I had completely cleaned the valve and hoses less than 200 miles before hand. There is no doubt in my mind that there is some oil going through the PVC valve and into the intake manifold. I agree that the gauze must be clogged or perhaps missing altogether. I'll have a better idea next week when I take the oil separator off to clean and inspect it. If the material inside of the separator cannot be cleaned is it possible to pull it out using a needle nose pilers or other tool? If so can I just stuff replacement gauze back into the canister? Or does it need to be cut open to replace the material inside? I drove the car about 75 miles without the PCV valve. There was nothing in the catch container. Without sucking the oil vapor out and not expecting much blow-by due to the compression figures, that does not surprise me. I will need to bring another hose from the container back to the PCV valve to see how much oil is lost through that route, but I am not planning on that unless the oil burning continues to be a problem after the seal replacement. What I did learn today is that the oil is still disappearing. During the drive I did see a puff of smoke from the exhaust on two occasions. There were probably more, just not visible to me. So oil down the valve stem still seems to be the prime candidate, but perhaps in tandem with the oil passing by the separator. Regarding the rocker shaft, it was not replaced during the rebuild. If I see it is worn when I install the seals I will replace the shaft and whatever else is needed to bring it all back to spec over the winter. I will not attempt do that top side, I'll remove the head. Guy, thanks for explaining how the o-ring seals work. Keeping the oil from running down from above doesn't seem to be sufficient. I have to believe there is a lot of oil being tossed around inside the valve cover, and it seems a good bet the valve stems are getting a healthy splash. Prop, I enjoy your humor. You are entertaining.  |
| Paul Noeth |
| I for one, would be interested if someone can explain how the PCV is designed internally and how it works. I do know that the suction provided at the intake manifold is way too strong for the breather to be used as a direct and unregulated connection. So the Pressure Control Valve must in reality be a Suction Control Valve, with some sort of arrangement which closes, or at least limits the suction when the manifold depression is high and opens up when the depression is lower. So how does it do this? And presumably any mechanism can go wrong, or go out of adjustment and suck too much. |
| Guy W |
| I wasn't convinced Guy. I didn't think the pic was clear enough, hence my "IF". :). "Suction Control Valve, with some sort of arrangement which closes, or at least limits the suction when the manifold depression is high and opens up when the depression is lower. " Exactly that Guy. There's a spring in it, and it's a balance between the pull from the vacuum and the pull from the spring. There isn't a constant vacuum at the inlet manifold, it varies with throttle opening. Higg vacuum shuts the pcv valve, low vacuum lets it open under spring pressure. It flutters at stages in between. It's my guess, that even with a fully working one, there will be oil residue on the mushroom. It's probably why bmc dumped it and went for the Y piece connection to the a low constant vacuum source at the carbs. Prop's obsessed with rusty breather canisters. We had EXACTLY the same futile discussions about the engine sucking. I'll bet my ar*e that you can clean that canister all you like and it won't solve your problem. And, unless you can see evidence that the cannister has been apart, then there WILL be a wire mesh inside of it. Just swill it in petrol. Paul you wrote. "What I did learn today is that the oil is still disappearing." So that's WITH the pcv DISCONNECTED. Hence it's NOT the pcv causing the problem. You can see small puffs of smoke, and barely notice a change in oil level. To notice a change in oil level, you must have more that a little oil, going down the valve guides. And since you've established that it isn't the PCV, because you disconnected it, I'd start looking elsewhere. I had a leaky head gasket once. Compression fine, it was only leaking from an oil passageway. I too was using extra oil. But that DOESN'T explain your earlier comments, that this engine HAS ALWAYS used too much oil. Earlier you wrote --- "When I bought the car in 1972 it burned as much oil as gas. Exaggeration, but you get the drift. We paid $250 for the car if that is any indication of its condition. After driving it for a couple of years (and suffering jokes about being a mosquito fogger) I rebuilt the engine myself. I replaced the rings, etc. and had the head rebuilt by a local shop. After getting it back in service, the engine never quit burning oil. I drove it for 2000 miles or so and it was burning about a quart every 500 miles (sound familiar?). A leak in the hydraulic clutch line put the car out of service and I just parked it. For thirty-some odd years. I didn't do anything to it for storage, just parked it. " It sounds to me as if you've NEVER cured the original oil burning problem. You've improved it, by fitting new rings(TWICE), but what it may well need, is a rebore. |
| Lawrence Slater |
| Guy, This is from the later workshop manual - does it answer your question? Richard  |
| Richard Wale |
| Doug. The breather arrangements on Minis and Metros are slightly different to Spridgets. There was only ONE oil filler cap for the 1275 and 1098 Spridgets. GFE6003. I'm not sure about 948's they might have used the chrome vented job originally. |
| Lawrence Slater |
| Thanks Lawrence. I knew WHAT the valve does, and WHY but not the HOW. Your text doesn't explain the latter, but the illustrations Richard posted gives the idea. I think I would only really fully understand the mechanism if I had one to dismantle. Is the disc on the top of the spring physically attached to the diaphragm? |
| Guy W |
| I had one briefly on my 1275 when I got it. From memory the rubber diaphragm is seperate to the disc, as shown in the pic. Here's a pic(from the web).  |
| Lawrence Slater |
| Thanks Lawrence, that's helpful. I had imagined that the breather pipe connection would be above the diaphragm, but clearly it isn't! When there is little or only low manifold suction the spring will remain extended with its plate raised, supporting the diaphragm clear of the lower raised ring inside the casting. The breather is then connected direct to the manifold. When suction is higher than the breather tube can readily supply ** the diaphragm will be pulled down against the plate and against the spring tension, compressing it. If the suction is higher still, the diaphragm will seal against that inner raised ring inside the casting, cutting off the breather pipe feed. You can see why they might "flutter" as Lawrence describes. ** Asterix - the amount that the breather tube can supply is unlikely to be limited by the tube itself as this is relatively large diameter. Unless there is an awful lot of piston blow-by it will be limited by how much air can be drawn into the crankcase. So this is where the oil filler cap breather holes (and dipstick, and any other orifices) becomes critical. If there is too much free air entry then the diaphragm will not close off, despite high manifold suction and presumably it will then continue to draw excessive oil vapour up the pipe. |
| Guy W |
| The fact that there is now a catch can on the oil seperator hose and its still burning alot of says alot I NOW dont think the problem is the pvc or the mesh inside the oil seperator... both my be contributing... but not the source of the problem Im not sure im even a fan of the idea that its oil seals submerging in oil from a worn rocker...as that would have to be ALOT of wear on both the rocker shaft, valve guilds, and the vlave seals to burn 1 qt of oil every 500 miles Its been reringed twice once with factory rings and agian with deves I think it maybe time for a rebore /over bore of .20 It could be a blown head gasket on the oil side... but you would notice that based how it ran and the strong likely hood that there would be alot of oil in the radiator How many miles are on the engine ? Im leaning heavily on the notion that its just worn out pistons and bores, or possibly even a cracked or broken piston/ landing... Prop |
| Prop and the Blackhole Midget |
- Blue smoke is only occasionally visible during shifts and does not seem to be continuous. - Compression readings are: #1 � 175 #2 � 175 #3 � 175 #4 � 179. (Engine warm. All plugs removed. No oil added to cylinders. Air cleaners in place. Throttle closed. Maximum pressure reached.) - When examining the spark plugs only #3 is dark and oily. The others are tan and dry. - Using about one quart of 20W50 every 600 miles. The Midget has been driven 1,800 miles since it was returned to service. Okay... I just noticed one issue The compression test was done with the throttle closed, not WOT, so that will have a big impact on the compression numbers Next issue is the #3 spark plug is the only plug thats wet with oil, ... and thats with an engine that has sat for 15 years with rings that are still 3000 miles away from being seated and broken in ... my engine has around 2500 to 3000 miles and im still getting some oil on the spark plugs (less and less as time burns by) and not loosing any noticeable amount of oil ... esp not 1 qt every 500 to 600 miles I have to say if only #3 is showing signs of burning and the other plugs are clean then there is a catostrophic failure in #3 or you have a massive oil leak somewhere on the engine ... rear crank seal, sump pan, front engine plate....something just isnt adding up Prop |
| Prop and the Blackhole Midget |
| I've seen a couple of comments about the compression test being done with a closed throttle. Why is that so important? I understand that the engine will breathe better with an open throttle. I would expect the compression to rise faster with an open throttle. It obviously still gets some air with the throttle closed. I've heard that a compression test is done with four compression strokes. After four compression strokes I was getting about 150 psi, but because the throttle was closed I kept cranking until the pressure no longer increased. Does that completely negate and falsify the results? At the time I was looking for a reading that was out of whack. All the readings were similar, with either four strokes, or letting it reach max pressure. That indicated to me that there wasn't a major problem with the rings or head gasket and I needed to look elsewhere. Would I learn something different if I did a compression test with the throttle wide open? Prop, the car has 66,399 miles on the odometer. I don't remember the exact mileage when we bought it back in 1972, but I would be surprised if we put more that 6 or 7 thousand miles on it. The car was 6 years old at the time and the mileage was likely in the upper 50,000 range. It was owned by a teenage kid who obviously abused and neglected it. But from the wear on the pedals and other indications the mileage was accurate and not 150,000 miles, but I have no way to prove that. It now has 2,300 miles on the rebuild. I will put the new valve stem seals on next week. If it continues to burn oil I will drive it until the snow flies and then take the head off for a look see. |
| Paul Noeth |
| After thinking about this for the past couple of days I think the path forward needs to be focased on where 1 qt of oil is going every 500 to 600 miles As you have stated, no dripping on the floor, only spark plug #3 is showing signs of burning oil, you have a catch tank connected to the oil seperator and that tank is dry, and I dont think its possiable to loose that much oil in such a short amount of time thur the valve stem guild with a leaking valve seal The only thing I can think of that fits all the above is a busted/ cracked piston or rings on #3 cly. I wonder if the rings were not gapped properly during the last re-ring as in to tight and the ring broke the #3 piston ring landing Thats the only thing I can think of that makes scence... that would leave the other spark plugs dry and clean, it would cause alot of blow by to over power the pcv valve, it would allow alot of oil to be burnt that could easly match the 1qt every 500 miles . it probably would hold decent compression esp if the landing broke on the 2nd ring or oil control ring piston landing...and fitting apiston ring to tight is an easy thing to do Prop |
| Prop and the Blackhole Midget |
| Paul Compression test only of any use if wide open throttle. We keep cranking till the pressure on the gauge is very steady and hardly going up. Peter |
| Peter Burgess Tuning |
| Paul, I have found little difference between open or closed throttle compression tests. You had good balance and high numbers, and that's all you needed to know from the check. Has it used oil from when you first got it back after the ring and head work? There is a common style of oil control ring that has color markers on tips of the expander. The idea is that if you see two colors you know you didn't overlap the ends. I have read that it is possible to do this correctly, and then have the ends jump over each other when the ring compressor is used, at which time you can not see the ring. The result is reduced pressure on the rails of the oil control ring. Since the oil control ring is not responsible for compression, it is possible to have good compression even with a problem with the oil control ring. But, lets hope it is the valve seals. Charley |
| C R Huff |
| Hi Paul. You say you are using 2 US pints of oil for 600 miles. In real english ( ;) ) that's 1.6 UK pints. If that's all going down you're valve guides in just 600 miles, you need new valve guides/stems I reckon, and there would have to be a lot of oil sitting in the rocker cover to deliver it too. Note what Peter just said about the throttle. You can't be certain about the compression the way you did it. But you can have good compression, and still loose oil up the bores. Your engine BORE mileage, is circa 70K miles. You have a set of rings in it, that have done circa 2000 miles, but if the bores are out of shape, new rings won't fix them, even if it improves the compression. 70K miles isn't overly excessive, but most cars of the day back thea, were smoking a bit when they got to 70K miles. How good are the pistons? Were the ring grooves worn? Were they measured? You've just said that the kid who owned it probably abused it. Most kids of the day, would have thrashed the crap out of a 2 seater sports car. I did. Charley. Paul wrote earlier -- I reposted it -- that the car was a smoker when he got it. Even after 2 re-rings, it's never stopped using oil, just uses less. 2 US pints of oil/600 miles may be less, but to me it points to something more than valve guide seals. |
| Lawrence Slater |
| I hadn't realised it was using anything like that much! I thought that was just a typical Prop exaggeration! Earlier descriptions was of an occasional puff of blue on the overrun. I would still happily replace valve oil seals without pulling the head, but l agree, that isn't going to cure this problem! |
| Guy W |
| Lawerance... I think we are starting to conjel on this, there is just no way you can loose that much oil thur 1 intake valve guild on cly #3 I think charly may have the inside track on this one... esp these being orginal factory pistons that had 3 compression rings plus the oil control ring but im still holding to my guns that its a busted piston at the ring landings Lawerwnce, You make a great point about worn out bores and pistons, and for a while I thought that also... but the little caveat is that ONLY #3 spark plug is oily #s 1,2, and 4 spark plug are clean and oil free But I do agree with 70,000 on the clock... its almost time for a PROPER rebuild with new pistons and a re-bore of the cyl. back to perfect round Prop |
| Prop and the Blackhole Midget |
| Wopps... I may be wrong about there being 3 rings on the factory piston, this is NOT a 1275 engine but rather a 1098 ??? Sorry about that Prop |
| Prop and the Blackhole Midget |
| Originally 1275's had 4 ring pistons I think. My 1275 engine still has a set of original type pistons in it. I thought 1098s did too. But 3 or 4 rings, it shouldn't matter if the bores are good. What colour is the oil? After only 2000 miles I would expect it to be pretty clean still. Especially as if you are replacing 2 US pints every 600 miles, you have effectively almost changed all the oil since you last put new rings on it. If the oil's black, then I'd be looking at a head gasket problem around #3, or something wrong in that bore. Are you sure it's really using that much oil? I agree, something doesn't add up. |
| Lawrence Slater |
| Lawerance... On my orginal engine I cant remember if it had 3 or 4 + the oil ring... but I remember thinking there are alot of rings on this thing Prop |
| Prop and the Blackhole Midget |
| Btw... for those playing along at home in the UK 4 usa qt = 1 usa gallon On a 1275... its around 3.5 usa qt to fill a 1275 to proper spec So im guessing 3 usa qt to fill a 1098 engine to spec ?? Prop |
| Prop and the Blackhole Midget |
| Haynes says for 948, 1098 and 1275 sump AND filter capacity is 6.5 Imperial pints or 7.8 US pints (3.9 US quarts) or 3.7 litres. It also says capacity of oil filter 1 imperial pint, 1.2 US pints (0.6 US quart) or 0.57 litre. Frankly I don't believe a word of it. What do you think? It has nothing to say about the 1500. At least my edition doesn't. |
| Greybeard |
| I think that's right Rod. Says the same thing in the BMC workshop manuals and even in the users manual. Being more specific about where all this oil is going, -- #1, #2, and #4, plugs are dry and tan in colour. Only #3 is black and oily. So not only is it using 2 US pints per 600 miles, it's all being lost presumabley in number 3, because there's no sign of it being burned in the other pots. So if the valve guide is the cuplrit, then it's only #3 inlet guide allowing all this oil to leak down through it. And if that's the case, I wouldn't expect it to be firing very well on #3 either. I would expect to be able to hear at least some uneven running. Could the 2 US pints lost every 600 miles, be wrong? Maybe it just seems like that. |
| Lawrence Slater |
| I just cant imagine 1 qt every 600 miles down the valve guild, if it were the case... there would be other issues like the valve stem slqpping the inside of the guild and tearing its self apart just from the slop alone... I think it has to be in the piston area Prop |
| Prop and the Blackhole Midget |
| I replaced the seals on the intake valves. I found nothing wrong. The new o-ring seals are a lot smaller than the seals I removed. Maybe they expand over time, but I am not sure how that would happen. In any event, they appeared to seal properly at the top of the valve stem. I don't know what the engineers were thinking when they designed these seals. I also installed the later style seals that go over the valve guides. Those do make sense to me, at least more so than the o-rings. That said, I think everybody is right, it seems unlikely that a quart of oil is going down the valve guides every 600 miles. And yes, that figure is correct, a quart of oil is going somewhere every 600 miles. I have not driven the car yet, but when I do I am not expecting the oil usage to change much, if at all. I am also not convinced it is the pistons or rings. When I rebuilt the engine in '75 (or whenever), I brought the block and head to an automotive machinist for inspection. They measured the bores, checked for roundness and taper, flatness of the block, and I believe they even Magnafluxed it looking for cracks. I had them rebuild the head because I did not have the tools. So when I put it back together and it continued to burn a lot of oil I logically assumed I screwed up somewhere. That is why I had it professionally rebuilt again when I decided to restore the car. They could not find anything wrong with what I did. They put in new rings, bearings, valve guides, etc. and it still burned oil. If it continues, and I expect it will, I'll take the head off as soon as the driving season is over. Unless there is something obvious, like a head gasket leak or scratched bores, I am not sure what to look for. The top side does not seem to be worn much at all. The valve rocker shaft does not show excessive wear. I can see where the shaft looks polished, but I can't feel any deep scratches or worn areas when I move the rockers aside. I cannot catch a fingernail on anything. I cannot feel any movement between the rocker and the shaft. FWIW, the Harbor Freight Universal Overhead Valve Spring compressor does not work well on the 1098 head. I had to modify it by cutting it down to fit into the tight quarters between the valves. Even with that it was difficult to compress the springs enough to remove or install the keepers. The Indian rope trick worked great however, not only preventing the valves from dropping into the cylinder, but also keeping them immobilized while removing the keepers. I brought the pistons up by putting the car in gear and rolling it, rather than using the starter to move the engine. This gave me good control on how hard the rope was pressed. The job turned out to be real pain. I am going to clean the oil separator, but I am not expecting that to make much of difference either. I'll drive the car a couple of hundred miles and report on the oil consumption. Other than that I think the horse is dead and we've beaten it sufficiently. |
| Paul Noeth |
| Paul, When checking the rocker shaft for wear did you feel the underside as that is where the wear occurs not on the top side. |
| David Billington |
| Paul, If you dont belive there is damage in cly #3, in the piston / ring area.... where do you think the massive leak is comming from? I know thats something you dont want to accept... but it certianly ticks off all the check boxs Id suggest waiting to work on the oil seperator, if its like the 1275 the entire front of the engine has to come off, but I dont know about the 1098 and how there set up Luckly we only have abother 6-8 weeks of good weather then you can dig into it Good luck Prop |
| Prop and the Blackhole Midget |
| With the stock piston having 4 compression rings... (thank you lawerance) and the oil ring It would be very easy to install a ring upside down, in the wrong grove, chip the edge of the ring, or even not get the oil ring properly seated... with that many rings just trying to AVOID a line up of the ring gaps thur all 5 rings is going to be difficult at best, us trying to install a piston with just 3 rings (2 compression/1 oil) is not as easy as it sounds.. I cant imagjne 5, now thats a night mare plus working with pistons the dia of a coke can is not a fun time as getting the ring contractor sleve to fit that small a diameter is like fitting trianges in round holes Im just saying... dont discount the cly/piston/rings so easily out of hand, lets face it 4 cyl X 5 rings there is a lot of built in room for error, esp if a pretty girl walked past the front of shop in 1975 with her skate board and saterday night fever john travolta LP record....40 years ago Wow I was 10 in 1975, now im 50...what aride its been Prop |
| Prop and the Blackhole Midget |
| Hi Paul. Only #3 plug is black and oily. You disconnected the oil breather hose, and still consumed oil, -- which elliminated the separator as a cause. But even if it WERE the cause, it wouldn't restrict the oil to number 3. All the plugs would be oily. But you say the others are dry and tan. Valve guides on #3, were/are extremely unlikely for that amount of oil consumption, and you have elliminated that now too. An oil leak with so much oil loss, you would have seen that by now. That leaves you 3 options. A leaky head gasket. Or; A crack in the head or the block, but you say both have been checked. Or; Something wrong with #3 bore, piston, or rings. With that amount of oil being burned, not only should you see an oily plug, I'd expect an oil residue in the tail pipe too. Have you looked? It's a mystery worthy of at least 600 or even a 1000 posts, just as the oil sucking engine breather threads were. lol. |
| Lawrence Slater |
| You can go further than that. If only #3 is showing signs of oil then the problem isn't normal wear and tear. All the pistons do the same moleage so wear would be evident on them all, more or less to the samecextent. It must be something more catastrophic like a broken ring or damaged piston. But the high oil consumption predates the last rebuild so either of those faults would have shown up when it was stripped down and rebuilt in 2000 and something. Which leaves damaged bore, but not just worn or the others would show the same symptoms. There is another explanation - the conspiracy theiry onev- tat the mechanic worked on the head, replaced the crank bearings but didn't actually inspect the pistons and rings, despite claiming to have done so. |
| Guy W |
| There is another explanation - the conspiracy theiry onev- tat the mechanic worked on the head, replaced the crank bearings but didn't actually inspect the pistons and rings, despite claiming to have done so. CHA CHING !!! Prop |
| Prop and the Blackhole Midget |
| Let me swing this pendulum back the other way. If he is only burning 4 qt of oil only on #3 for 1800 miles for the past 15 years How the heck has that spark plug not fouled yet... its almost like the continuous burning 100 year old light bulb Haha... sorry im just trying to do my part to make this a 300 posting thread Prop |
| Prop and the Blackhole Midget |
| Sorry about all those typos! Something to do with typing on a smartphone whilst travelling on a bus around twisty, bumpety Lake District roads! |
| Guy W |
| Guy, I just figured you were getting your irish on a little earlier today Haha |
| Prop and the Blackhole Midget |
| OMG ! My secret is out! |
| Guy W |
| Is it possible? An IRA threat to make the world burn more oil? ;) |
| Lawrence Slater |
| Isis ??? / irish ??? They do have a similar sound when spoken outloud... haha |
| Prop and the Blackhole Midget |
| Okay... I've replaced the o-ring seals at the top of the valve stems and added the later style seals where the valve stems enter the valve guides on the intake valves only. I also removed the oil separator and cleaned it by soaking the interior with carburettor cleaner and then flushing it with carb and brake cleaner until the liquid ran clear. (I also screwed up the paint on the separator which created a bit of a delay in getting everything back together.) I've driven it now for a little more than 200 miles. The result... drum roll... reduced oil consumption. Based on measuring the oil line on the dip stick and assuming the upper and lower lines on the dipstick represent a bit over one US quart, my preliminary calculation is one quart every 1500 miles. This is, at best, an educated guess, so it could be a little more or a little less. I will need to put on a lot more miles before I know for sure. If that turns out to be true, it would mean adding one quart between oil changes (3,000 miles) versus adding five quarts between oil changes. I can live with that. After 200 miles the #3 plug looks just like the other plugs. All of the plugs were lighter in color (bordering on being too lean from my limited experience in plug reading). Obviously, I removed the carbs and heat shield when I did the oil separator. I did not change any settings on the carbs, but after reinstalling them, the engine was idling about 300 rpm faster than before and seemed to be vibrating more at moderate rpm. I rebalanced the carbs, reset the idle and richened the mixture (2 and 3 flats respectively) until there was no change in idle when lifting the pistons 1/32". (That process seems so imprecise. How do you lift a piston 1/32"? I use a screw driver and turn it slightly under the piston to lift it rather than using the lifting pins, but still, did I lift it a 64th? 3/64ths? Exactly a 32nd? Who knows? Plus, you now have a screw driver in the air stream.) Anyway it now runs just as good as it did before, however I'm not sure the carb settings are optimized. Another discussion for another thread. Adding the valve seals was a pain, but not so much that I would consider putting the new style seals on the exhaust valve stems as well to see if that further reduces oil consumption. However, as it stands, I am no longer seeing any puffs of blue smoke after shifts, even at night with lights on from the car behind, when it was most visible. Sorry, this thread will not live to be 300. I case I have not said it, I appreciate everyone's responses to my many questions. Your advise, knowledge and experience helped me tremendously. Thank you. |
| Paul Noeth |
| Glad to hear that it worked. A quart every 1500 miles isn't bad. That's about what my engine uses. And along the way you learned a few new things. |
| Martin Washington |
| Sorry paul, Not so fast... you have further defined the orginal problem and created another new problem 1st the orginal problem... if your now only burning 1 qt of oil every 1800 miles and before where burning 5 qt every 1800 miles by simple changing valve seals ... and now the plug is no longer showing signs of oil burning... thats a problem, it means your valve guild in #3 is massively over sized and the new seal is short for this world the gap must be grand canyon large to put that much oil thur the guild and the valve... id be wery of driving it for fear the valve is slapping around The new problem you created... you now have a vacume leak ! If you reinstalled the carbs and they now run lean by 4 flats and before they ran great before adjustment... classic sign that something didnt seal correctly... a missing gasket or a crack in the black spacer if it got dropped, a carb not seating flat or a nut not securing properly... track it down, lean can do more damage then to rich Sorry to be the blue santa cluase eatting your halloween candy Prop |
| Prop and the Blackhole Midget |
| I wonder if the #3 intake is a differant valve then the rest, perhaps a stainless racing valve with a wasted stem that could account for some of the extra gap between the guild and the valve...but that cant be the whole story... that is ALOT of oil flowing down #3 intake and thats with a partial intact valve guild seal in place I just cant imagine the amount of gap there must be...the machinist must have been having a monday irish morning ... haha Prop |
| Prop and the Blackhole Midget |
| Glad you fixed it. :). I don't know about an air leak, but I agree about the consumption. If replacing the oil seal, and adding the later type(inlets only), has resulted in #3 running oil free and tan, then I agree, there's a problem on that inlet guide/stem. And whilst the problem may have been fixed for now with a band-aid, it won't last long, -- imo. Of course, the original estimate of oil consumption may have been completely wrong. If the new oil seals have cured it, then I suspect that was the case. It's either that, or something else has been rectified that you may not even be aware of fixing. But I can't think what. Cleaning the separator was a good idea, but given that only #3 was oily, it wasn't the cause, and can't have been the fix. So my money's on an overestimate of oil consumption. "I am no longer seeing any puffs of blue smoke after shifts, even at night with lights on from the car behind, when it was most visible." Imo, If you'd been using a quart every 600 miles, all down one pot, you'd have seen a lot more than a puff at night when changing gears. It would have been visible as a trail of smoke in broad daylight, and I think you'd have smelt it too. |
| Lawrence Slater |
| Blue Santa, aka Prop, what else could have happened to cause the engine to run lean after the carbs were reinstalled? Could it be possible that cleaning all of the crap out of the oil separator caused more air to enter the manifold via that route? Dunno. I agree there was a lot of oil going down the valve stems. Where the guides ever changed? Dunno. Are the valve guides too big? Dunno. Are the valve stems too worn? Dunno. Did I create a vacuum leak? Dunno. I can tell you I did not drop the spacers. There are no gaskets missing. The carbs are seated properly. The nuts are tightened securely. But you make a good point so I will check for a vacuum leak. What I do know is the fact that the oil consumption has been reduced by the addition of the valve stem seals which points to the problem being in the head and not with the cylinders/pistons/rings. And that makes me happy. I would rather deal with a problem in the head rather than one in the block. |
| Paul Noeth |
| Lawrence, funny you mention smell. It does seem to smell better. Before I was getting a little exhaust oder that no longer seems to be there. I think everyone is putting too much emphasis on the oily #3 plug. It was darker and showed signs of oily wetness that the other plugs did not show. But after I added the stem seals, and before I cleaned the oil separator or touched the carbs, I drove about 20 miles and all four of the plugs were lighter in color. Maybe the seals will not last and I will have to have the head rebuilt. Time will tell. |
| Paul Noeth |
| Hi Paul, You're the only one able to see the engine and it's bits. We can only go by what you say. If I had a dark oily wet plug on one cylinder, that suggests something to me. Given that you reported using 2 pints of oil in 600 miles, along with that description of one plug, the emphasis was just about right I reckon. You also said new valve guides were installed during the rebuild. That kind of elliminated them, and pointed to a bore/ring/piston problem. Anyway, hopefully you've sorted it, but if you're original estimate of 2 pints in 600 miles was indeed correct, I suspect it won't stay sorted. How long do oil seals last? Mileage? |
| Lawrence Slater |
| Hi Paul, What oil are you using? And do you take care not to overfill. Adding a bit extra for luck in this case can cause excessive oil consumption. |
| Guy W |
| I have to agree with lawerance on all points Plus... the old oil seals where intact and leaking 1 qt ever 600 miles so i think thats proof that the new seals only have a life span of a few hundred to maybe 1000 miles Im glad its working out for you... but im afraid its a short lived fix As to the vacume leak... im not being accusatory ... im just offering possiable common examples of where and why a vacume leak is occuring.... the point is, something is a miss and not as was before the carbs where removed... 4-5 flats is almost a complete turn ... the carbs are adjusted on the bench to 12 flats (2 full turns)... your at almost 3 full turns richer. Where ever the air leak is, its fairly sizable Is the dissy vacume advance hose hooked up to the front carb Btw way there are push pins under the carb that push the carb piston up to its proper height. Prop |
| Prop and the Blackhole Midget |
| I just noticed we are 1/2 way to 300, only 149 postings to go, Sooo lets talk about which brand of hose clamps was used to secure the hose to the oil seperator... im sure we can burn 10 postings right there alone.... haha Prop |
| Prop and the Blackhole Midget |
| Prop, my apologies, I just can't figure out how to write more clearly. Front carb -- richened by two flats. Rear carb -- richened by three flats. Considering you don't know how the jets were adjusted when I took the carbs off (and I did not change the setting), please explain how you calculated that I am three full turns too rich. <<the old oil seals where intact and leaking 1 qt every 600 miles so i think thats proof that the new seals only have a life span of a few hundred to maybe 1000 miles>> Let me try again. 1) I replaced the old o-ring seals at the top of the valve stem under the cap. These seals do absolutely nothing to prevent oil splashed on the exposed valve stem from running down into the guides. 2) I ADDED the new-style (umbrella seal or whatever they are called) at the bottom of the valve stem. These seals fit tightly around the top of the valve guides and slip fit around the valve stem. This type of seal will shed most of the oil running down the valve stem before it enters the guide. Guy, I am using Kendall GT1 20w50. I rely heavily on those two little marks on the dip stick. I never put oil in above the upper most mark. Lawrence, I initially said the engine used about one quart every 600 miles. That was an estimate rounded to the nearest double zeros. As time went on, I was able to more accurately calculate the amount. Before installing the new seals the engine used exactly one US quart of oil for every 568 miles driven. Gentlemen, the horse is not only dead, it is drawing flies. Despite my sarcasm I do appreciate your input. Prop the next 148 postings are up to you. |
| Paul Noeth |
| Paul, the reason l asked about the oil is that others have used modern synthetics. I did too at one time and it just seemed thinner and my oil consumption went up as a result when l was using it. I thought it might account for what l think is still a continuing slightly raised consumption. But at only 1800 miles since the rebuild it could still be rings are bedding in still. The other point was because when l got my 1275 engine it turned out that it had a rogue dipstick! Definitely a proper A series one, but the markings were wrong, and too high. I recalibrated it with fresh markings by filling the sump and oil filter with the known correct amount and marking the stick accordingly. Prior to that, oil consumption was high if l kept it topped up to the original mark. As l recall it was about 1/4 inch too high. I think the significant improvement is you adding the top hat seals. The O ring seals work tolerably well on low performance engines with closely fitting valve stems / guides. But if your guides have been replaced it is likely they are designed for lead-free fuel and the guide clearance is increased. In this case the top hat type seal is almost essential. I use them on all 8 valves, not just the intakes. The seals are flexible and there is no reason at all to think that they will suddenly wear out rapidly with the greater valve to guide tolerance. Don't feel hassled by the answers you get on the BBS. People do genuinely try to help, even with some doom and gloom comments ! |
| Guy W |
| "Before installing the new seals the engine used exactly one US quart of oil for every 568 miles driven" Well gloom and doom or not. That's a lot of oil, and if accurate, and if the only thing that's reduced that consumption is the addition of the later oil seals, then I still think there is a base problem, yet to be resolved. The horse is far from dead I reckon. I don't even think it's at the knackers yard gates yet. ;). |
| Lawrence Slater |
| I must say ...using 1qt of oil per 600 miles sounds much better then consuming 2 pints in the same distance... come on lawerance get with the program I like beating horses, missouri mules, and red headed step children... this one still has alot of life before its ready for the glue factory Money, its almost as good as cash Prop |
| Prop and the Blackhole Midget |
This thread was discussed between 04/08/2015 and 26/08/2015
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