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MG MGB Technical - Oil leaks

Oil is leaking from the rearmost side tappet cover. I fitted a new cork gasket a while back and it is leaking again. WAny thoughts.
Trevor Harvey

The fiber washer on the bolt that secures the cover tends to leak. The cover must also not have been overtightened and distorted.

I use Permatex, not RTV, clean all surfaces well and make sure that the fiber washer is also sealed between the bolt head and the side plate.
Glenn Mallory

any sign of oil coming up dipstick hole too?
it could be positive crankcase pressure if rings are aged - or on a new rebuild if they have not seated well.
i ask about dipstick as that is usually the easiest way out for oil if pressure is cause.

i had it coming up dipstick when i installed supercharger on fairly new rebuilt engine . i managed to control it by drilling slightly larger hole in oil filler. not ideal as that is supposed to be to pull air in not get fumes out....but it worked. the crank vent to carb simply isn't enough.

G



Graham Moore

IMHO that is probably the worst designed part on the MGB.
Bruce Cunha

The cork seals were never that good, they are worse now. The rubber/neoprene ones are much better with an O ring under the washer on the screw. And, as Glen pointed out, the covers get distorted by over-tightening in an attempt to cure the leak.
Allan Reeling

I replaced mine recently, and the rubber seal was slightly too small for the cover, I had to clamp it in place overnight and not take too long fitting it. Used non-hardening flange sealer on the cork for the front, and together with bolt seals they didn't leak. Installed with the exhaust and manifold in place, just removed the carbs.
paulh4

When my front side cover leaked several years ago I had been using neoprene gaskets. When replacing it I noted that the new neoprene seal was not a great fit to the front plate but persevered. I struggled to get a seal using a range of sealants with no long term sealing. As a last result I decided to buy cork gaskets and give that a try. Much to my surprise the cork gasket fitted the front plate perfectly. Putting the neoprene and cork gasket side by side shows that they are different sizes. (See photo) I now have neoprene on the rear plate, cork on the front and no leaks for several years. I use a grey Permatex RTV sealant. Hope this helps.

Richard.

Richard Thompson

Those under-size front gaskets seem to be the norm then. I assumed mine was just a one off fault. I did manage to stretch it and glue it in place though , which worked. It just begs the usual question; "why can't they be made the right size?"
Allan Reeling

Richard, That is exactly how I solved my leak there. Cork on the front, red neoprene on the back.
Bruce Cunha

I assumed the different sizes was because the covers are different shapes at the seal surfaces. Doesn't explain incorrect sizes though.
paulh4

This thread was discussed between 29/03/2017 and 03/04/2017

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