Two piece Rear Main Seal

[Dennis A.]

appreciate any and all tips on how to install a two piece rear main seal that will stop the oil from leaking. I have shoe-horned in the top seal without tears and still get leaks. Engine is a 350.

[Joe R.]

Re: Two piece Rear Main Seal

Dennis,

Fel-Pro makes a rear main seal with a double lip. I have seen these in a light gray color and also in black. Sorry, I don't know the number but have had great success with this seal.

As far as installation, the leak probably occurs at the ends of the seal or around the seal. For this reason I always use some silicone RTV very sparingly around the outside of the seal where it goes in the groove. Also a very small dab on the ends of the seal. I also put a very samll dab at the end of the main caps as an old mechanic once instructed. Don't get crazy with the RTV as it can also create problems.

Only had one leak using this method and it was because the seal had a bubble that would distort the seal when it became hot. Strange problem but it happened.

JR

[William V.]

Re: Two piece Rear Main Seal

Dennids

Felpro makes a rear main seal (red in color) that is designed for highoutput & high rmp engines. The part number is P2912. The cost is around $23 which is double the price for the gray. However the extra cost is well worth it.

Felpro also provides installation instructions with the package which ehco Joe's installation tips.

BV

[Timothy B.]

Re: Two piece Rear Main Seal

I believe the felpro 2900 is the seal that some people have problems with. The 2912 is the same as the GM 10121044 rear seal and that's the one to use.

I have the same problem with my 63 rear seal and I sealed the cap mating surface but I believe it's the 2900 seal. I plan on changing it out this spring.

[Joe L.]

Re: Two piece Rear Main Seal

appreciate any and all tips on how to install a two piece rear main seal that will stop the oil from leaking. I have shoe-horned in the top seal without tears and still get leaks. Engine is a 350.

Dennis-----


If for some reason you're not applying sealer to the areas that JR referred to and as well-described and illustrated in the Chevrolet Service Manual, you will ALWAYS have a leak, no matter how many times you do it over. Applying the sealer in the proper areas and in the proper LIMITED amounts is 100% CRITICAL.

If you are applying the sealer as described, then I would check the crankshaft's seal surface for wear. If there is ANY wear on this surface, especially a groove of ANY depth, the seal will not work properly and will DEFINITELY leak. In that case, you need a seal with a displaced lip so that it puts the seal lip at an unworn area of the crank. I understand that such seals are available but I have no information as to part number or manufacturer. They are not available from GM.

[Joe L.]

Re: Two piece Rear Main Seal

appreciate any and all tips on how to install a two piece rear main seal that will stop the oil from leaking. I have shoe-horned in the top seal without tears and still get leaks. Engine is a 350.

Dennis----


As an add-on to my earlier post, I've found that if you do need the OFFSET double lip seal, it's Fel-Pro #BS118291.

[John M.]

Re: Two piece Rear Main Seal

I replaced a few hundred of these in a past life here's my .02:

1) Stagger the seal so it sticks out of the block maybe 3/8'. That way the seal, and the main cap don't line up, much like you would stagger piston ring gaps.

2) Do not use RTV (IMHO). It just doesn't work right in this application, use anerobic sealer with a 1/16" bead running from the seal out to the edge of the cap.

3) If you have excessive bearing/journal clearances they tend to leak more, because more oil flows (sprays) out of the bearing. Back in the day we used to always install a +.001 bearing (with a plastigage check afterward) when we did a seal. I doubt you can get these anymore, but be assured if your bearing is worn to the copper, it wouldn't hurt to replace it.

4) the surface the seal rides on needs to be real smooth, cleaned up with 1000 grit smooth with nothing you can feel. Spray it out with carb cleaner then comppressed air (you'll need a shower immediately after). Check it real carefully for nicks. Any nicks will instantly destroy a seal.

5) The double lipped seal is cool, but OE partsheld oil long before it came along.

[John F.]

Re: Two piece Rear Main Seal

Joe, What do you mean by the offset? Do you mean turning the ssal in the groove about a1/2 in. or so?

[Clem Z.]

Re: Two piece Rear Main Seal

i have found most seals leak when the engine is just shut down and the pressure against the seal lips goes away. i machined 2 shallow "V" grooves in the bearing insert so the oil in the bearing would drain back into the pan. i used this on boat engines as that is where a rear mail bearing seal leak shows up and it seem to work.

[Joe L.]

Re: Two piece Rear Main Seal

Joe, What do you mean by the offset? Do you mean turning the ssal in the groove about a1/2 in. or so?

John-----

By "offset" I'm referring to a seal which has a LIP which is at a slightly different position that the original seal. In this manner, it contacts the crankshaft in a non worn area. So, if there is a groove in the crankshaft's rear main seal contact area caused by the previous seal, the new one "offsets" from that location making the groove "irrelevant".

[Dennis A.]

Re: Two piece Rear Main Seal

Thanks for all the help...I located the double lip seal #BS11829-1 and it is on it's way. Will use Permatex Ultra Coppper High Temp. RTV... What do you think?

[John F.]

Re: Two piece Rear Main Seal

Clem, Do you have any pictures of the grooves you machined?

[Clem Z.]

Re: Two piece Rear Main Seal

Clem, Do you have any pictures of the grooves you machined?

no i dont but after i get back home in middle of march give me a email and i will send you a sketch of what i did if you are still interested.