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MG MGA - Tapped cover gaskets

When replacing my head gasket recently I also replaced the 2 cork tappet cover gaskets, but sadly both are leaking small amounts of engine oil. I have been told that cork gaskets are notoriously difficult to seal properly and that rubber gaskets are a better option. Does anybody out there have any experience of these and would you recommend them?
Thanks
Robert Sinclair

Rubber gasket are difficult to keep in place, likely to leak. Cork gaskets will always seal as long as the mating surfaces are clean and flat. Some recent issue cork gaskets are a bit too small, so you need to relieve the inside corners to lie flat. You need to seal around the bolts which are pron to leak. Use bolt, lockwasher, flat washer, and sticky sealant. Alternately use a flat washer with rubber O-rind molded into the center as a positive sealing washer. That would be a later model MGB part.
barneymg

Have had success with both, clean surfaces are important as Barney says.
Mike
Mike Ellsmore

I always seal mine to the tappet cover with silicon sealant. Clean thoroughly with degreaser and you can use clear bathroom silicon. Just lightly nip the cover in place and leave to set overnight. The next day you can tighten it down. When you want to adjust the tappets the cork will stay attached to the cover and can be reused many times. Do not be tempted to tighten too much before the silicon has set or the gasket will slide out.
A J Dee

When ever I fit side plate gaskets, I always glue them to the side plate first, let them dry then fit them, the same with rocker cover gaskets
Andy Tilney

Thanks for all your comments. I'll be sticking with the cork gaskets again, but will try to make a better job of it this time! My guess is that I didn't tighten the bolts enough last time, as I was worried about overdoing it and damaging the covers.
Robert Sinclair

Robert, Often part of the failure of these seals is that the covers have often been distorted by successive owners trying to cure leaks by keep tightening the bolts.
Allan Reeling

The best solution is as others say, glue the cork gasket to the cover, hammer the edges flat first and make sure that the raised section in the centre of the cover is not recessed from previous over tightening. then use the MGB dished washer and grommet on the mounting bolt and don't over tighten. Then it SHOULD be leak-free
Dominic Clancy

Thanks again to all of you for your comments and advice. It's just a pity that the carbs, exhaust manifold and heat shield have to be removed first, turning a 10 minute job into a 2 hour one!
Robert Sinclair

see my comments on tips for removing carbs - now a 15 minute job and the same to replace
Dominic Clancy

Job done.
I've just finished replacing the two cork gaskets, and thought some of you might be interested to know what was causing the oil leak.
Well, both covers were slightly bowed, because of historical over-tightening of the central bolts, but that wasn't the main culprit. As mentioned by Barney and Dominic, it was the lack of a decent seal between the bolt and the central hole in the cover. So apart from straightening the covers, with the help of a rubber mallet, I have now added a half inch rubber tap washer to the bolt, in addition to the flat washer and lockwasher ... plus a healthy dose of sealant!
Fingers crossed.
Robert Sinclair

This thread was discussed between 28/07/2018 and 02/08/2018

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This thread is from the archive. The Live MG MGA BBS is active now.