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rear main seal interferes with oil pan gasket

672 Views 3 Replies 1 Participant Last post by  dorfs
I'm putting a new oil pan gasket (Fel-Pro cork/rubber, 4-piece set) on my 87 YJ's 258, this is after some other work like crank replacement, etc. has been done.

My concern is this: the lower tabs on the bottom half of the rear main seal protrude downward a bit... and the end tabs on the new side gasket pieces are supposed to fit into the groove on the rear main bearing cap, but the rear main seal tabs are in the way so the gasket tabs have to take a slight bend and be fit *over* the rear main seal (sandwiched between the rear main seal tabs and the oil pan).

I am worried that this will create a couple of tiny spaces between the gasket and the block, where water could get in if I get deep enough in it (and I will). Is this normal, and will the small gaps be closed when the gasket becomes oil-soaked? Or is there some way I should deal with this to prevent water going into my oil pan?

Here's a really bad ascii-graphic to illustrate the prob. This is how it would appear if you were to look at the motor directly from the rear.


S=rear main seal
G=oil pan gasket
P=oil pan

Note that the oil pan fits pretty flush against the gasket, I just couldn't figure out a way to represent that in ascii. Sorry this message is sorta confusing, it's hard to explain without being able to look at the actual problem. If anyone knows what I'm talking about, please advise. :p

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You are making a good attempt to describe the problem....I'm not sure I follow it exactly....but I have done this a couple of times....when your putting the gasket on from underneath it seems backwards....the side (pan) gaskets have a tab that fits between the bottom rear seal and the block. About the only way to get it in is use RTV to stick the pan gaskets to the block, then you can put the pan up in position...the rear seal will then fit over the tabs of the pan gasket.....

I guess this is about as clear as your description....hope it helps.

John......southern CA
84CJ7, 3"lift, 32"BFG, 4.10's, ARB Locker, Solid Axle's, Durabak
I'm having a little trouble figuring out your question and it's been a while since I did mine. I also went with the 1 piece neoprene pan gasket. But in your situation I believe there are 4 gaskets that meet up at the bearing cap. 1) the bottom main seal. 2)the pan seal for the groove in the bearing cap, and 3&4) the two cork pan seals.
The bearing cap is recessed into the block so those "L" don't sit up as high as you might think. I believe I used RTV in the pan seal groove and where the pan seal made contact with the main seal "L" tabs.
Another thing that was in the Fel-Pro instructions was to put a small amount of "Anarobic" sealant along the bearing cap chanfer. I believe I used a loctight 518, but I believe that the RTV will also work, but the anarobic sealant is better for metal on metal where you don't want to change the clearance.
Have look at the picture of the bearing cap and main seal and then ask some more questions. I didn't have any pictures of the pan seal that would have been useful since mine was the one piece.
I was also told to glue the pan gasket to the block and then bolt the pan on. That way it stays in place.


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Do yourself a favor, and throw that 4 piece cork gasket away. Get a factory Mopar one piece rubber one. I have never seen one leak. The college built my first 4.0 and used that gasket, and it always leaked from the front holes in the timing cover. I changed it with a factory Mopar. It took 5 minutes to pull the pan, 1.5 hours to clean the old cork off the motor, and 10 minutes to put the new one on.

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