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MG Midget and Sprite Technical - Crankshaft Rear Scroll Seal

Does anyone who has fitted a rear lip seal to a 1275 engine, still have the original upper scroll seal and would be willing to part with it?

I know someone that is having trouble with a leaking lip seal and would like to revert to original.
Dave O'Neill 2

Haven’t got one Dave but when you have solved his oil leak can you sort mine please 🤣
Mike Fairclough

IS there any consensus on which is best - scroll or modern alternative?
P Peters

None, and I mean none, of the rear oil seal kits work. I keep saying this every time the subject comes up.
The crank flange on A series engines was only machined smooth but NEVER machined so the surface was concentric to the big end bearings. Consequently, if the flange is out of concentric by as little as 1 thou it will wear the oil seal until the oil just bypasses the seal.
The crank flange was never made concentric until the Maestro and Montego A series engines were made because they used an inline FWD gearbox (4 or 5 speed) from Volkswagen which was designed to have a conventional oil seal built into the adapter between the engine and VW gearbox.
Otherwise you are onto a loser unless you are VERY lucky and production tolerances just happen to combine to produce a concentric crank flange.
Rob
MG Moneypit

I have spent nearly 20 years trying to get the Morris Minor Centre seal kit to work, and gave up. It worked for a month or so and then leaked again, every time. I even had the crankshaft flange sleeved and machined. On the current engine the rear main bearing cap and half moon have been skimmed to close them up, and then line bored again. The occasional drip now but that's normal.
Les Rose

Steve Kiel's version of the rear crank seal acknowledges and neatly side steps the issue that Rob highlights. I'm just very surprised that it hasn't attracted more followers.
GuyW

Unfortunately my face seal can only be used on the 948 and 1098 engines where there is sufficient material to be able to dress and polish a suitable mating face for the V seal to bear. The 1275 engines do not have a suitable form however it may be possible to build up the appropriate faces with epoxy, possibly metal loaded, to provide a suitable feature.
S G KEIL

Sorry for misspelling your name Steve.

Can you give an update on how well it works, or its longevity in everyday use?
GuyW

My Peter May/Keith Calver one doesn’t work either. Can’t believe I fell for all the guff, especially after trying the original Peter May/MMC one which was even more useless. At least the original one was easy to fix, engine out, bang on the old scroll cover and it hardly leaked at all, unfortunately the new one is a ‘no going back’ type.

I think I’ve said it before, a leak is better than a flood. Stick with your scrolls!!

John Payne

I am a scroll fan too. If the engine is carefully assembled and Hylomar or similar is used to seal the rear cap to the block and the sump gaskets are carefully fitted then providing there is a method of creating a negative vacuum or use a PVC valve then the leak is limited. I rebult my 1275 acouple of years ago and I don't have any drips.
Bob Beaumont

Nobody have a spare scroll then?

Dave O'Neill 2

Dave, try Peter May. They fit their kit (that doesn’t work!) so must have some spares unless they throw them away. They should have one at least - mine!

Some will say that they are machined to the particular block and won’t work with a different engine. I personally don’t think that is exactly the case. They may well have been machined with the block but the diameter of the scroll is the same on every crank so the radius must be exactly the same on all scroll covers. As the scroll cover is slotted to allow adjustment I don’t think it’s a problem fitting one to a different engine.
John Payne

Thanks John, I’ll give him a call.
Dave O'Neill 2

Sorry for a stupid question but I am trying to trace a leak on mine . From the rear scroll does it leak down the rear of the sump or into the bell housing. I get quite a drip from the split pin in the bell housing and can’t work out if it’s coming from inside the bell housing or being blown back from the sump and dripping from the split pin as the lowest point ?
Mike Fairclough

Not a stupid question at all.

I think it could feasibly run down either side of the back plate, so could end up in the bellhousing.
Dave O'Neill 2

I remember a fellow midget racer told me he stuffed a rag between the sump and back plate and hammered it in using a thin piece of wood and it lasted a race meeting . It wasnt you Dave by the way !
Mike Fairclough

You’re right, it wasn’t me. I didn’t use a piece of wood, I just pushed some rag in there with a screwdriver 😁
Dave O'Neill 2

I’ve got a little catch tray on mine. It’s deep enough to stop unsightly pools of oil and keeps scruitineers happy in the paddock etc but shallow enough that under hard cornering the oil spills out. A temporary measure until next time the engine is out to try and make the seal work better.
John Payne

Hi Guy
I do not have a working Spridget but fitted such a seal on a MASC members engine around 8 years back with currently no obvious leakage from the bell housing drain.
Also surprised that I have not received other queries re such 'supplementary seal' as it is so easy and cheap to fit but can only be carried out as part of a full engine strip down.
I have made tooling to suit small and large crank journals and with a bare block it only takes a few minutes to face the requisite sealing surface and with no detriment to anything else !
A simple task to make tool but if required I could undertake necessary dressing/polishing procedure on a 948/1098.
Where are you located ?
If a spare/scrap block and crank were available I could investigate viability for a 1275 solution.
Cheers
S G KEIL

Steve, we exchanged a few emails about it shortly after your first Mascot article. At that time I only had a 1275 so in my case I shelved the idea for future reference. But I am just surprised that there hasn't been a widespread uptake in the method. That's why I was asking about how well the seal has performed now over a good period of test time.
GuyW

Guy
As previously mentioned I believe the same principle could be used on the 1275 by building up a suitable mating surface for a face seal.
The V seal can be more readily installed on the 1275 as the crankshaft flange is of a smaller diameter than 948/1098.
Thorough cleaning/degreasing and ideally light abrasive blasting to provide a suitable key to ensure an optimum physical and chemical bond.
Some temporary works would be needed between the bottom bearing cap and rear cover interfaces together with a central plug such that epoxy could be poured to fill depression.
S G KEIL

I ditched my Peter May seal about a year ago, It had been fitted by Southam Engineering when they had rebuilt the engine in my Sprite for a previous owner. It had been fitted at the insistence of the owner not by a recomendation from Southam. I spoke to them on the phone and even after 5 years still had my upper scroll in their parts stash. They may have others. I simply rubbed the two ends of the scoll on a piece of flat emery papaer a few times and bolted everything up. I do have a catcher tank under the bell housing but after a year there is virtually no oil in it.

I found the oil slick under the car (no exageration) wasn't caused by seepage through the lip but from the face of the aliuminium casting that sit against the main bearing cap. The cap has an uneven surface and the casting cannot be bolted to this. To stop leaks the join is smothered in silicone and mine had degraded. I beleive thier is now a kit that requires the mains cap and part of the engine block to be machined flat so the seal carrier can be positively bolted to the engine. This is an engine out and a vist to a machine shop job and is irreversible and costly. I am now happy with the original set up


Jan T
J Targosz

The Rivergate rear seal has been better sometimes, worse others. As mentioned above, on the 1295 conical crank surface, the lip seal does not bear on a perpendicular surface so the solution is not technically correct. I have found that centering the seal VERY CAREFULLY upon assembly seems to make a huge difference in the outcome (and outpouring).

When my 1971 was new, I tried and tried to get the leak at the rear fixed under warranty. They finally got the timing cover leak fixed by replacing the harmonic balancer but some of the Rivergate rear seal replacements have been more successful than others when servicing the clutch.

MGs leak oil. At least they did when they were new.
Glenn Mallory

Dave O, just come across this thread - I have a few spare upper scroll seals; they are graded and stamped or cast with a letter ex-factory, any idea which one you need?
David Smith

J Targosz I am so glad I found this thread before I started buying fancy kit to fix the leak
Just about to take the engine out and hopefully come back here for advice once I see what set up is on it
R Deans

This thread was discussed between 07/08/2023 and 07/09/2023

MG Midget and Sprite Technical index

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