Rear main seal conversion disaster?

I would check the fit of the cork oil pan seal. It shifting during assembly, or missing altogether, could explain the dry test run and the splurge once tilted back. Remedy would only entail the sump off.

To check the oil gallery end bolt, take out the rearmost side gallery bolt and fiddle a wire towards the back. If the bolt is missing (which I doubt because Dick M. has a point) the wire will eventually scratch at the flywheel.


I think this is it, the cork seal is not there. I now distinctly remember it being left in the workbench … I know the rubber seal that fits in the sump groove is there, but not the cork one. Damn it!!

Either/or: it doesn’t need both.

You mean it takes the rubber seal OR the cork seal right?

Depending on the style of groove, in the pan and sealing ring, yes.

I cannot remember exactly what/when pan and seal ring difference was between the models, but as long as there’s one or the other and it’s properly sealed, it only needs one seal.

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Ok, so, i will eventually take that engine out… again and investigate…

Buying a bicycle is becoming an attractive option…


Someone said 4.2s (or something like that) went to the rubber seal… but both fit. I went for the cork seal as it is prettier, and after all, it was a cork seal from the factory.

It’s either cork or rubber, not both. Pretty good idea that this might be missing.

…if you‘ve run the engine it can’t be related to the oil gallery and if you put the seal in nicely it has to be the main seal :confused:

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Last time mine was apart I had to buy my own 1/4" cork blank and cut my own. The one I ordered from a usual was less than .2 and had no squish.

Yes I’m pretty sure they switched to rubber after the 3.8 E.

They both come with the gasket kits we‘ve had before.
@MartinScherz has unipart kits from the 420/420g days that have cork but no rubber so I am a little sceptic, since my low miles 7L block also had cork. The cork does fit just the same, different machining or not. Anyways, seems rubber is generally better.

Yes every Payen kit I’ve seen has had both in it. I don’t use those kits any more though since I started using Cometic. There actually is a Cometic rear sump gasket. It’s awful, and I refused to use it. It’s super hard and doesn’t compress at all. Feels like plastic.

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It is cheaper to make the gasket kits with both pieces. The cork seal is used where the fitting groove is in the rear seal housing. The rubber seal is used when the groove is in the oil pan. You need to use the combined parts so that there is only one groove. IE: no groove in pan and rear main housing, either or, not both.

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I NEVER recall that… thanks!

The lower half of the seal seems to be nicely snug with the crankshaft (see photo, the orange stuff is antiseize compound).

But I discovered something that *may" be my salvation. The two long bolts holding the oil pan on either side of the seal housing are missing!!! May be the bottom of the threads open up inside the block…

Unless there is something wrong with the top half of the seal…

Fingers crossed…