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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Peter May Oil Seal

I thought a drip tank had provided a medium term solution for the rear crank oil leak. Unfortunately my Peter May conversion, fitted by a previous owner, isn't working and after a 100 mile trip there was at least half an egg cup of oil in the tank. Oil appears to be leaking from the bell housing split pin and also from the join between the back plate and bell housing. It looks like I will have to lift the engine and do some remedial work. All on line forums covering the A Series engine recommend reverting to the original set up. Will any parts of my engine have been machined to fit the May conversion and will any original parts have been removed/changed. My local engine machine shop says I may need a "rear cover" part number 120 in the workshop manual page 24. Since the leak is comming from between the engine and bell housing I suppose there may be an issue with core plug at the rear of the cam shaft but I am afraid it is an engine out job. Before I start this though has any one got some advice -pleeeeeze.

If I need a rear cover has anyone got a spare for sale?

Jan T
J Targosz

Don't know about the Peter May kit but I do remember Peter Burgess only recommending the Keith Calver kit and that definitely needs machining work to fit it.

Oil leaks can also be about the engine breathing system and its sealing at points and input output at others, mine's best with the original black plastic vented and filtered oil filler cap (rather than bling chrome with small hole) and dipstick washer fitted, otherwise I don't get the correct amount of rocker cover seepage (last bit is a, bit of, a joke).

I expect you've found already there's a bit on these subject in the Archives here.

https://www.calverst.com/webshop/sprite-midget/cst3002-rear-main-seal-kit-2-0-in-main-1275-only/
Nigel Atkins

My advice is bin it.

The good news is that the PM kit doesn’t need any machining so you can revert back. The problem my arise in that you may not have the rear scroll top cap (probably the cover you mention). This really part of the rear main bearing cap but is separate and held on by 3 bolts. Lots of people will tell you to never touch, remove, adjust it etc but I’ve removed mine during rebuilds and refitting and adjusting isn’t rocket science.

So if you haven’t got the old one then you will also probably be told that it is specific to that particular block and a new one will need to be line bored to the rear main. I’m not so sure about that, I think it’s well worth getting hold of another from somewhere and giving it a go. It’s surely got to be the same diameter as all the cranks are the same and the three holes are slotted for adjustment.

A few years ago I tried one of the PM kits and after about 100 miles it dumped loads of oil out. So removed it and not having the time or inclination to strip the engine I just bunged the scroll top cap back on, centralised it, tapped it down as far as it would go and tightened the bolts up. Since then apart from an odd drip it has been fine for many miles/years. Though you have to get the breathing system right - either negative pressure or open.

My thoughts anyway having been in a similar position.
John Payne

My advice exactly follows John's

If I ever do decide to chase the scroll leak some day in the future the Keith Calver method is the only possible alternative to owning an oil well.
Bill sdgpM

Thanks for the info. It's good news that I can revert to the original set up. Considering the reputation of various seal kits there is no way I will have any parts machined. I have tinkered with the scroll covers on my TF's EXPAG engine and had to open out the screw holes and then scrape the cover to match the crank. Unfortunately this means blueing the cover, turning the engine, removing the crank, scaping high spots and repeating the whole process - possibly a number of times. I had hoped to simply fit the cover whilst the engine was still on the hoist. I think I can find a cover but it is not from my engine so I will probably have to do a fair ammount of dismantling.

Even though I have made a well fitting catcher tank it takes time for drips of oil to actually fall into it. Whilst some of the drips are still on the engine/box air rush is forcing them further down the gear box. A sponge in the tank, pressed up against the engine could help but there is so much oil leaking I would have to drain the tank weekly.

Jan T
J Targosz

I am wary of these seals. In the 80's I had a race engine prepared by Longman for my modsport sprite and they did not fit one. No drips!

The Frog has a 1275 which I rebuilt last year and its also dry but I have the negative crankcase pressure set up with the connection from the timing cover to the carbs. I also ensured the rear main had a smear of sealant between the block face and the cap and used cork not rubber sump end gaskets.
Bob Beaumont

A few years ago someone (Steve Keil?) wrote an article for the MASC magazine describing a different type of rear crank seal than the normal ones. Unlike the Peter May version it didn't use the normal circular type of shaft seal which he claims wear quickly due to slight excentricity of the the contact surface on the crank. I forget exactly but his used a face contact seal running, I think, on a machined surface of the end cap.(?) It was a pretty simple DIY-able system. It was being trialed on a couple of cars at the time and early results were good, though I haven't seen or heard of any follow up results.
GuyW

You should be able to fit the cover while the engine is on the hoist, or at least offer one up to see if it looks/feels ok.

When you’ve removed the parts of the PM kit (it’s originally from the Morris Minor Centre I think) then you will be able to see the scroll part of the crank and the main cap top surfaces. This will be behind the flange for the flywheel (flywheel will obviously be removed).

When you’ve cleaned all the oil and old sealant etc off it you can try the replacement cover. It just slides down behind the flywheel flange and if you can feel that it sits on the main cap and still has slight side to side movement (only a few thou I guess) then it should be ok. You will need a gasket as there is one between the cover and block, any conversion set should have on in it or just make one from some thin gasket paper. All I did was put some dabs of sealant on the ends of the cover, stick the gasket onto the cover with sealant and then slide it into place. Then I centralised it as best I could by feel and tightened up the 3 bolts.

Having just re read this I think you might have to cut the 3 bolts down slightly as they might be too long to get in due to the flywheel flange.

If you don’t want to chance it then unfortunately the only other option is to remove the sump and crank and set up the scroll cover with the crank spinning freely. That way you can feel (or at least try to!) any interference on the scroll.

Good luck!
John Payne

I have been searching the internet and making phone calls all day but cannot find one of the scroll top caps that I need to convert the engine back to standard. Has anyone got one they can sell me or even suggest a possible source.

Thanks in anticipation

Jan T
J Targosz

The Peter May Seal kit actually originated from Mini Mania in the USA. The kit design is ok but I understand it needed a better seal (life of the seal supplied with the kit was short.

APT in the USA were planning to manufacture some of the standard half-moon seals. Ringing them might work out better than an e-mail.
Daniel

I've said this before and I'm going to say it again. The edge of the crank flange on the A series engine is not machined to be concentric to the crank. The first A series engine where the crank was ground concentric was for the Maestro/Montego 1.3 because it used a seal that ran on the edge of the crank flange inside an alloy housing about 1" deep which was designed to allow a VW gearbox to be attached to the end of an A series engine. Part of the alloy housing carries the seal.
Due to manufacturing tolerances you may be lucky enough to have a perfectly concentric crank flange, in which case the PM and other seals will work well. If the crank is just 1 thou out of concentric in a short time it will have caused the seal to open out by 1 thou all around causing oil leaks. If it's much more than 4 thou out of concentric you will have no chance at all.
Rob
MG Moneypit

Jan, one thing you could try is looking for a damaged or worn out block on eBay etc. Also it could be worth checking if the 1098 with 2” mains is the same as they are usually cheaper. There is a 1098 block on eBay at the moment for £85 that has one fitted. It’s at the MG Centre Wrexham which I’d normally say steer clear of but he might be worth giving a ring to see if he has one off a 1275 or if he’ll do a deal on the 1098 one.

Another option would be to ask on the MASC Facebook page. Or the Modified or Race Austin Healey page. Maybe the Midget and Sprite Challenge page as well! My thinking is that race car owners tend to have worn out blocks, spares etc.

John Payne

I have a 2013 invoice for the rebuilding of my engine £3000! I have spoken to the outfit that did the work and they say the May kit worked at the time but after 8 years the seal has probably hardened. But would you believe they think they still have the removed scroll top cover in a box somewhere. Removing the engine will be a winter job. I have a good DTI and will check the run out of the flange and decide what to do then.

Jan T
J Targosz

Jan if your engine builder can't find the semi-circular half of the rear main cap, I have a spare.
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David Smith

Is there a decent and affordable (DIY) sollution for these oil leaks? As I have asupercharged A-series leaking is (still) a big issue

I have breathers everywhere
a.o. arnold

"Breathers everywhere" sounds like your problem!
Reverting to the correct crankcase extraction ventilation arrangement should reduce the oil leakage.
GuyW

Jan

You seem to be assuming that the seal is at fault. Is this truly the case or is the crankcase being overpressurized due to a fault/blockage/whatever in the breathing arrangement?
Oggers

The breathers are connected via the PCV to the inlet.

Breather in:

- valve cover (1)
- sump (2)
- chain front side engine (1)
a.o. arnold

Ah, I thought you meant lots of open-to-air breathers. I guess its because the supercharger results in more piston blow-by then, which the breathers struggle to keep up with.

For a cheaper oil seal modification I mentioned earlier that Steve Keil published an atrticle in the MASC magazine (May 2018) about an alternative seal method he has devised which might be worth trying. I intend to, next time I have my 1275 engine out.
GuyW

http://www.midgetandspriteclub.com/wp-content/uploads/2019/10/newsletter201805.pdf

Found it, is there anyone out there having experience with this sollution?
a.o. arnold

I have tried to open the link but it doesn't appear to be working for me.

In the mean time I have been pondering over the May oils seal - I see the exact one is adverised by the Morris Minor Centre. Has anyone actually fitted one of these that worked?

I have the original fitting instructions and they are very simple, basically remove the top cap and bolt everything on. They do say that the faces on the new top cap and the bottom one should align but don't say what to do if they don't. I wonder if the seal would work if carefully fitted by an engineer. All three components in the kit simply bolt together and there are no locating dowels. If the rear face of the seal counter bore is not square to the the crank boss or concentric to it there is every chance of a failure. I know with certain MG T Series kits a circular, alighnment collar is provided which is fitted over the crank boss and into the seal counter bore before everything is tightened. This ensures the seal will be concentric with the crank. When I eventually lift the Sprite's engine I will set up a DTI to check alignment of the kit, especially concricity. I will also check for run out on the crank boss but since this locates the flywheel surely this must be true? Has anyone any thoughts on this?

Cheers

Jan T



J Targosz

Sorry no idea about Morris Minor Centre, or Peter May, oil seals but Arnie's link work directly for me using a PC.

Note, unless I've read it wrong (always possible) the system described in the hyperlinked article seems to only go up to the 12CC engines.

Perhaps a cut and paste on an i-can't-phone might work.
Nigel Atkins

It would be useful if the article gave actual details of the seal used rather than letting the reader guess but I presume it's this type of seal https://simplybearings.co.uk/shop/p515242/VA50-VITON-Rubber-V-Ring-For-Shafts-48-53mm/product_info.html .
David Billington

Managed to open up the site by writing the adrress down on paper then keying it into my Android tablet. Life is now getting interesting. The V Ring seals turn with the shaft and lip runs on the face of the larger bearing race - which normally has a fine, ground finish. I allways thought they were used to keep oil and dirt "out" rather than keeping oil in. I doubt they would be effective with high pressure oil but they could be ideal to stop the small ammount of oil that leaks past the scroll. My preferred option looks to be ditch the lip seal conversion, revert to the original scroll system and fit a V Ring seal to stop the slight leak from the scroll. Problem now is designing a fixture to clean up the faces of the bearing cap and the top cover. Possibly a mandrel through the main bearing caps and a fly cutter to clean the faces. A nice wee problem to ponder over?


Jan T
J Targosz

Jan,

Maybe you need a bigger screen or zoom in as the mandrel you mention is shown in the 2nd image and he says he used abrasive discs to clean up the rear surfaces of the main cap and upper oil catcher part.

"Dressing and polishing of the seal contact face is achieved by the use of a suitably sized guide bushing to suit engine type where the centre hole is accurately sized to receive the pilot of the facing pad and various grades of abrasive discs made to fit inboard of the screws used to secure the ‘rear cover’ which completes the scroll housing."
David Billington

If you read to the end of the article you will see that Steve says to contact him for more details. Which I did. I suspect at the time the article was written as the method was still relatively untested he perhaps didn't want to give away too much detail on a public platform.
GuyW

Hi Dave and Guy,

I think this is an important topic since the seal could provide a simple, cheap and effective solution to the oil drip which could readilly be fitted during engine rebuilds.

I noted how Steve had fitted a bush into the rear main bearing cap and used this to centralise a mandrel/flat plate to which abrasive paper had been glued. I am uncertain as to how rough the castings are and to the stability of the mandrel with a single support. I would have thought that perhaps an additional support in the centre of the block would be adviseable. Two ball bearings, clamped in the main caps with a central shaft? Obviously line boring with a facing cutter to the rear would be the ideal and eminently feasible at an engine rebuild. I note Guy has spoken to Steve. Did he provide any extra info such as the type of seal used and how effective the mod has been with a number of engines over a period of time.

Cheers

Jan
J Targosz

There's a top cover for sale on Ebay. Presume it's for an early car.
f pollock

Which category does the cover appear in.

Jan T
J Targosz

BMC Austin/Morris A Series,Austin A35 A40 ect,Rear Crank Main Seal Housing
f pollock

Thank you much appreciated.

Jan
J Targosz

The easiest way to fit the scroll cover is with a straight edge running along the main bearing housings. Although you can do it with the crank in place it's almost impossible to ensure you get it fully concentric. Short of line boring (or squeeze casting JB Weld) a steel straight edge should remove the element of error. But I'll throw another idea into the mix. In the early '70s I ran a full race 998 FJ engine which leaked pretty badly. I rang Stuart Turner who was BMC's Competition Manager and he told me the works cars added a full contact rope seal into the recess. So this was in addition to maintaining the factory 2 thou scroll clearance.
A rope seal is likely to be more forgiving of crank movement (whip) than face contact neoprene so unlikely to wear out so quickly. Certainly on high revving V8's many builders have found neoprene more prone to leaking than self lubricating rope seals. Of course it would need a bit of investigation with due consideration to rope sizing and rotary speeds, as I'm sure material fitment and graphite performance would be key for longevity.
f pollock

The crankshaft supplementary rear seal that I developed uses a standard face seal running against the back of the rear main bearing cap/rear cover(eyebrow) which requires to be dressed flat and provided with a suitable surface finish.
It is only suitable for 948 and 1098 engines having 1-3/4 or 2" journal as the 1275 is lacking in material at this location, however one of our MASC members here in the NW was able to fit and attach suitable laser cut pieces to compensate.
I made block bushes for both journal sizes and have been readily able to achieve a satisfactory flatness and surface finish without any necessity for a more complex bearing arrangement.
At the least it should keep the abrasive clutch debris from entering the sump via two drain holes provided for the scroll arrangement.
S G KEIL

I have mentioned previously that I am forced to do something about the crank rear oil seal. About five tea soons in my catcher tank after 100 miles. The options are replace the lip seal in the Peter May kit that is currently fitted to the car or revert to the standard set up. Thanks to these pages I managed to purchase the upper part of the original sealing arrangement on eBay but I am not certain if this is from a 1275 or smaller capacity engine. I attach some pics and perhaps someone can confirm which type of engine it is from. It only cost £5 so if it isn't from a 1275 it's no big deal. I have also been checking out Utube and found several related episodes. One shows how to fit the Peter May seal and the other is a discussion by John Twiss of University Motors. He advises line boring the bottom end but this is a big job. As an alternative he suggests wrapping a layer of cling film around the scroll and replacing the top cover with a smear of JB Weld on the contacting surface. My concern is that a leak is unlikely to come from the upper part of the original sealing arrangement but rather from a worn main bearing cap. The only cure for this will be line boring and that's assuming the scroll itself is fine.

It is getting to the stage where I am actually looking forward to removing the engine just to see what is going on.

Jan T






J Targosz

the pics certainly look like 1275 upper housing. Currently on way back from Denmark otherwise I'd fish out one and give you some dims to check against. Maybe later this week. The 1275 ones usually have a letter stamped on them, believed to be sizing info much like piston grade letters. Do you not have a third option to remove what's in there and fit the Calver design seal kit? The latter is reckoned by some experienced racers to be the only one that works properly.
David Smith

just my observation on this as im logged in - the Calver kit looks remarkably like the MED Engineering rear seal kit too. not saying its the same as i dont know, but these guys are very good in my opinion and worth considering.
p bentley

Having had problems with rear crank oil seals on both my Sprite and MG TF I am convinced there basically are two issues, one that would be costly to remedy and the other that will never be sorted. The first one concerns the finish on the crank boss which as standard is quite rough and can rip a seal to pieces. The solution would be to fine grind the surface or fit a speedy sleave. Both would require a partial engine strip. The killer though is the length of the rubbing surface on the boss. There is simply not enough "meat" for the seal to work reliably. I have checked out the MED site and they do comment on the surface finish of the boss.

Jan T
J Targosz

Hi all, I follow this thread as I experience oil leaks since many year. I am willing to invest some money, but only when it is a proven sollution.

Hope for someone with a real and working sollution
a.o. arnold

Hi Dave,

Thanks for the offer to measure housing but I managed to pop into Southam Mini Centre who rebuilt my engine in 2013 and fitted the Peter May seal kit. They still had my housing in their bits and pieces box. Just for the record the housing that I showed earlier is from an 850 A series. The 1275 one is bigger and as you suggest has a letter"E" cast in.

I must say that the facilities at Southam were very impressive and their knowledge of A Series engines second to none. They said the only A Series that is totally leak free is one from a Maestro which has a totally different rear seal arrangement.

Jan T






J Targosz

The Maestro has an alloy casting about 1" thick containing a conventional seal that runs on the edge of the crank flange. The flange is about twice as thick as the Midget flange and is ground concentric to the big end bearing centre line. The alloy cvasting converts the A series to mate to the VW FWD 4 or 5 speed gearbox fitted to Golfs of the same era. This is why no earlier A series engine can be successfully fitted with aftermarket oil seals.
As an aside, I bought a Maestro A series engine from a guy near Bradford who was fitting a 5 cylinder Audi engine to a Maestro. No idea if it worked out, sounds scary.
Rob
MG Moneypit

This thread was discussed between 25/08/2021 and 25/09/2021

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.