rear main seal small block

[Bruce W.]

Hey guys,
Have been speaking to a top restorer about the best rear main seal. He says he has had a lot of trouble this year with seals from fel pro. He has bee using cometic with good success. Does anyone have some experience with the Cometic rear main seal. This restorer said the last twelve cars he did with fel pro leaked and had to be redone.i replaced the rear main seal with fel pro and I get a leak coming out the inspection cover. No leak from anywhere else. appreciate you help.
Bruce

[Edward J.]

Re: rear main seal small block

Bruce, I have no info on the fel pro rear seals, but I have used fel pro many times over the years, there maybe a issue if these seals are made in China. But I had a lot of years experience chasing oil leaks, do some easy checks such as running your finger on the underside of the rear of valve covers, it’s so common to leak at this point and run down the block and look like a rear seal leak, another common area is the conners of rear intake seal and running down the back of block. Check oil pressure line fittings. If all looks good and you decide to tackle the rear seal look for a old Gm seal. I think the GM seals these days maybe a fel pro seal in the box, maybe Joe L. Can comment on this. I think the 70 and 80’s seal were blue and white bags or boxes of this era. If this is the way you go, let me know I can give you the tips you need to know to make it trouble free as possible. Let it be known than the General had a hard time seal a engine in all engines.

[Mark E.]

Re: rear main seal small block

... look for a old Gm seal.

Do these seals deteriorate or harden over time, even if in a sealed bag?

[Edward J.]

Re: rear main seal small block

Mark I would think they would live in a sealed bag, I would not think age would be a problem, but it depends on the environment it got stored.

[Bruce W.]

Re: rear main seal small block

Edward, Thanks for the advice. I will le you know if I do it. Do you have any experience with Cometic rear main seals. Fel pro appears to be a problem?
like
I said a top restoration shop told me they had to replace 10 out of the last 12 seals. All fel pro but are having good success with Comteic!! your experience?
Bruce

[John D.]

Re: rear main seal small block

Does anyone have info on the offset seal to use with worn crankshafts ?. Cant seem to find it.

[Joe L.]

Re: rear main seal small block

Edward, Thanks for the advice. I will le you know if I do it. Do you have any experience with Cometic rear main seals. Fel pro appears to be a problem?
like
I said a top restoration shop told me they had to replace 10 out of the last 12 seals. All fel pro but are having good success with Comteic!! your experience?
Bruce

Bruce------

There are several types of Fel-Pro rear seals. The cheaper ones are rubber. The best one is fluroelastomer. That one is Fel-Pro BS40013.

[Joe L.]

Re: rear main seal small block

Does anyone have info on the offset seal to use with worn crankshafts ?. Cant seem to find it.

John------

I know of 2:

Victor #191006901

Fel-Pro #BS118291
.
However, both of these are made of old-fashioned rubber, not the fluroelastomer that the best seals are made of.

[Joe L.]

Re: rear main seal small block

Bruce, I have no info on the fel pro rear seals, but I have used fel pro many times over the years, there maybe a issue if these seals are made in China. But I had a lot of years experience chasing oil leaks, do some easy checks such as running your finger on the underside of the rear of valve covers, it’s so common to leak at this point and run down the block and look like a rear seal leak, another common area is the conners of rear intake seal and running down the back of block. Check oil pressure line fittings. If all looks good and you decide to tackle the rear seal look for a old Gm seal. I think the GM seals these days maybe a fel pro seal in the box, maybe Joe L. Can comment on this. I think the 70 and 80’s seal were blue and white bags or boxes of this era. If this is the way you go, let me know I can give you the tips you need to know to make it trouble free as possible. Let it be known than the General had a hard time seal a engine in all engines.

Edward------


The GM rear main seal is GM #10121044 and is constructed of fluroelastomer. This seal GM lists for $45.

The best Fel-Pro seal, also constructed of fluroelastomer is Fel-Pro #BS40013. This seal sells for about $9.

Once-upon-a-time I was installing the above referenced Fel-Pro seal and I noticed it had the 10121044 part number embossed on it. I presume this means that this was the part that Fel-Pro supplied to GM since they could not otherwise place this GM part number on their product.

[Gary B.]

[Bruce W.]

Re: rear main seal small block

Gary, you and I both hate leaks. I have to get it fixed to pass the PV. Still waiting to see if anyone has had good success with the cometic seal. Mickie's Car Bar uses it and claims it is far better than Fel pro.
Bruce

[Joe L.]

Re: rear main seal small block

I don't understand how anyone with a 2 piece rear seal can achieve a 100% leak-free condition. Personally, I have never seen such a condition in a 2 piece seal engine. Maybe they exist, but I've never seen it. My 1969 350 had some seepage since the day I took delivery (which, incidentally, was 52 years ago today).

GM did not go to the 1 piece seal because the 2 piece worked just as well. As a matter of fact, even the 1 piece often leak and it's a WHOLE LOT MORE TROUBLE TO REPLACE THAT TYPE.

[Mark F.]

Re: rear main seal small block

...the day I took delivery (which, incidentally, was 52 years ago today)...

Joe,

Could you post a photo of your ride on the occasion of this 52nd B-Day?
Do you have a photo of it the day you picked it up?

[Joe L.]

Re: rear main seal small block

Joe,

Could you post a photo of your ride on the occasion of this 52nd B-Day?
Do you have a photo of it the day you picked it up?

Mark-----

I do not have a photo of the day I took delivery----I wish I did. I just never thought about it at the time. I am in Italy right now and don't have a lot of photos with me. However, I do have photos of the car that were taken on a trip to Death Valley in 1981. The car appears exactly the same today except it now has a soft top in addition to the hardtop. I ordered the car with hardtop only but I added a soft top in 1986. It now wears it's soft top virtually all of the time.IMG_0544[1].jpgIMG_0560[1].jpgIMG_0524[1].jpgIMG_0528[1].jpg

The first picture is the car in front of the Furnace Creek Inn in Death Valley. The second is from a campsite we stayed at the day before we stayed at the Furnace Creek Inn.

The last two photos are of the car the 1969 Corvette replaced. It was a 1968 Chevelle SS 396 with L-78 engine and M-22 transmission. I factory ordered it and took delivery in May, 1968. I delivered it to it's new owner 52 years ago today, just hours before I took delivery of my new 1969 Corvette. Curiously, the Chevelle would probably be worth 3 times as much today as the Corvette.

[Mark F.]

Re: rear main seal small block

VERY Cool, Joe...love those D-spoke Torq Thrusts on the '68, too!
thanks so much for sharing!