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MG MGB Technical - oil leak, black oil

I'm just starting to use my garage find of last year having spent the winter doing up the front suspension. This is really the first serious use the car has had. I'm seeing black oil dripping from the bellhousing and also the clutch lever gaitor. The little 'jiggle' pin at the bottom of the gearbox had been splayed out a lot so was probably not letting any oil out. Pinching it in let about half an eggcut of oil out. I have clean oil in the engine and gearbox. I have no evidence of clutch slip and I can see no evidence of oil on the back of the flywheel through the blanking plug in the back plate. I was told by the PO that the engine had been overhauled two years before the car was laid up so I assume that the rear seal is ok. Looks like an engine out job whatever. I assume the black oil is clean oil picking up carbon from inside the gearbox? Would this indicate which seal was leaking?

Whilst looking for the source of the leak I'm seeing some seepage from around the head gasket which is of the copper variety. Is the Payen type the one to go for (it was with the midget) if I need to replace it?
Steve Church

If it's black oil it'll be the rear engine seal. Even if it was the gearbox you'd still need to get the engine and box out. This way you only need take the engine out and it's a simple matter to replace the seal.

Bob
R.A Davis

The engine oil is clean. Where does the black stuff come from?

Aren't there problems associated with just taking the engine out. Like getting it to mate with the box when putting it back in.
Steve Church

Steve,

Since it was laid up for a long time, if it was mine, I would drive it a while and see if it quit leaking. Just make sure you keep checking the engine and gearbox oil. The oil may be black because of dirt in the bell housing. Plenty people pull the engine without the gearbox. Plenty people do it the other way too.

Charley
C R Huff

Charley, having had the car since last July, I've driven it less than 100 miles due do recommissioning etc. I don't plan on pulling the engine just yet (next winter). So I shall just have to keep an oil catcher tray handy. As long as it doesn't affect the clutch then I can cope with occasional topping up. It's just a bit annoying.
Steve Church

Steve

The oil may be clean now but has it always been that clean? My guess is not. I bought an engine and box a couple of month ago to use as spares for a re-build, the engine oil had just been change and was clean. When I split the engine and box the inside of the bell housing was covered in thick black oil, the clutch and flywheel were pretty clean. I lifted the engine and box out in one piece it's not difficult but it a fair sized lump of metal. Doing this means it's much easier mating the two at re-build time.

Bob
R.A Davis

Steve,

Your rear main engine seal has probably dried out from lack of use.

Some motor oils that are specifically labeled for high mileage cars have additives to make old engine seals swell in the hope that they will seal better.

Here is Castrol's offering:

http://www.castrol.com/castrol/extendedsectiongenericarticle.do?categoryId=82915476&contentId=7053315&nicam=USCastrolSearch&nisrc=Google&nigrp=Engine_Non_Branded&niadv=High_Mileage&nipkw=High_Mileage_Oil&gclid=CKDrzdy-nKgCFQEKbAodmis3IA

Steven 67GT

This thread was discussed on 14/04/2011

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