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Rear main seal always leaks

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Old 04-26-2006, 12:00 PM
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Rear main seal always leaks

I am obviosly having a problem with leaking rear main oil seals. I have installed a total of 4 rear main oil seals on two different engines and they always end up leaking, right away. So I am obviosly doing something wrong. The way I am doing it is to use a hammer to tap the seal into place until it is flush with the crank. But it always ends up leaking. I have 1 piece rear main seal blocks and use the Fel-pros. Will the "rear main installation tool" work better?
Old 04-26-2006, 12:14 PM
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The way you are describing doing it, GUARANTEES a leak. Tapping with a hammer is WRONG for either 2-pc or 1-pc seals.

The correct way to do a 2-pc is to use the little tool they supply, or something similar; and "roll" the seal endwise around the seal bore. Make sure that the little angled grooves in the mating surface of the seal are installed facing the way that as the crank turns, it PULLS the oil INWARD out of those little grooves, not PUSHES it OUTWARD. Use a little grease or motor oil or something on the back of it, to help it slide around the block or the cap and keep it from getting scratched. Leave the ends of the seal sticking partway out of the block and out of the cap, such that when assembled, the ends don't line up with the cap/block joint. Put a DROP of sealer, such as gorilla snot, on the ENDS of the seal. Smear a very thin coat of silicone on the mating surfaces of the cap and block, especially on the oil filter side (where the pressurized oi passage from the pump toward the filter is), paying particular attention to get enough in the corners of the cap register so that the cap is sealed to the block when installed.

For the 1 piece seals, the best way to do it is to put 2 blocks of wood in a vise, and "press" the seal into the carrier. Wipe a little gorilla snot in the bottom of the seal bore, such that the edge of the seal embeds itself into the sealer. If you try to "tap" the seal in around the edge with a hammer, you WILL distort the seal and CREATE a leak, EVERY TIME.

With either kind, wipe a little grease or oil onto the surface where it touches the crank; or onto the crank where the seal touches it.
Old 04-26-2006, 01:46 PM
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Flush with the crank

I hope you dont mean flush with the flywheel mounting surface.
Use a piece of wood and drive the seal ALL the way into the rear main housing. It should be flush with the outer face of the housing. You dont need any sealant at all, there are numerous grooves around the entire seal that will mate with the housing and prevent any leaks there. As stated above, coat it with some oil on the inside and carefully install it to prevent any cuts to the seal.
Old 04-26-2006, 02:29 PM
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The way with a vise and two blocks of wood sounds much easier, it also sounds like it would work better!


Originally Posted by madmax
Flush with the crank

I hope you dont mean flush with the flywheel mounting surface.
Use a piece of wood and drive the seal ALL the way into the rear main housing. It should be flush with the outer face of the housing.
Sorry. That is what I meant.
Old 04-27-2006, 03:34 PM
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Its very easy , i used a piece of wood and a hammer, no leaks so far. Be gentle with the hammer .
Old 04-28-2006, 09:57 AM
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Are you swaying to put the seal in the housing and then bolt the housing back to the block? Or to install the seal in the housing while it is bolted to the engine block?

If I install the seal with the housing already bolted in, how do I do it with a block of wood and a vise?

If I do it with the housing off, how do I get the housing and seal back on the block with out damaging the seal or poping the seal back out?

And the flat side points toward the rear of the engine, correct?

Last edited by Tibo; 04-28-2006 at 10:03 AM.
Old 04-28-2006, 10:32 AM
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Install the seal with the housing off. Its not that hard to get it on the block over the crank with it installed in the housing, there's a chamfer on the end of the crank to help you out. Just take it slow and dont force the seal into place.
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