I remember reading somewhere that the OEM Pontiac rear main seals (also called the "rope" seal?) is problematic . . . I think the article said they were prone to leaks.

I just bought a Fel-Pro OEM gasket set for my 455. Should I be looking for a better rear main seal?

Thanks :D :D :D

I remember reading somewhere that the OEM Pontiac rear main seals (also called the "rope" seal?) is problematic . . . I think the article said they were prone to leaks.

I just bought a Fel-Pro OEM gasket set for my 455. Should I be looking for a better rear main seal?

Thanks :D :D :D

You might say that the Pontiac rope seal is a leaker. I have never had a problem with the rope seals. The newer batch of rope seals provided with the engine gasket kits are of lower quality due to the absence of asbestos and are even more prone to leak. :( BOP Engineering recently came out with a Viton Rear Main Seal for both main journal sizes. 3" Main Seal..........$34.99
3 1/4" Main Seal....$34.99... [img]smile.gif[/img] :cool:

Other alternatives before the BOP seals did not always work well. Some people used to take a neoprene 460 Ferd rear seal and use it on the 3" main engines, and the Caddy 472/500 rear seal for the 3.25" mains.

Forget about using the seal that came with your Fel Pro kit and get one of the BOP seals. Installed correctly they don't leak.

Get the BOP. Have mine in for over a year now, not a drop!

Ditto. Do not consider anything but the BOP seal.

I put the BOP in my 400 was working great!Now after about 900 miles it is starting to drip a little :( I still think It is better than the new rope ones. I may be pulling the engine this fall anyway so I will get another BOP seal and try it again. SO I would also say yes go with the BOP seal.

Mr-Bratt - Clean the area up well and then check it closely. I have had two instances of leaking out of the rear passenger side corner of the pan that looked like a main seal leak. On one I just globbed a lot of silicone seal on it and it cured the leak.

BOP is the way to go. ;) ;) ;) ;)

Aren't there 2 rope seals though? (front and rear?) And should I replace BOTH rope seals?

Thanks

[ September 11, 2002, 04:45 PM: Message edited by: Bungee ]

The BOP in BOP Engineering stands for Buick-Olds-Pontiac. The rope seal is only in the rear, not the front. One half of it is in the block and one half of it is in the rear main cap.

I've never had a problem with the rope seals on any of the Pontiac engines I've built, or any of the Pontiac cars I've owned. Must have been lucky.

Taff - I am guessing that you have had the good fortune of running the older version seals. I was successful with those as well. I have not been successful with the new ones and a stick shift.

Bungee, here are the Instructions for the B-O-P rear seal. As Old Man Taylor said make sure you seal the rear of the oil pan itself correctly. If you need info on sealing the rear of the pan, check High Performance Pontiac Magazine July 2002 page 28 thru 35. http://www.bopengineering.com/main_seals_install.htm

OMT. Do you polish the serrations on factory cranks? I have been told they will cause seal to fail.

If you read the BOP instructions that i posted, you will note that it says (if you are using an Eagle Crank polish the rear seal surface) I polish the factory cranks also, never had a problem. Check the rear of the pan also. I feel that 99% of the leaks when using the BOP seal is from the rear of the pan not the seal.

My cranks have been the old factory originals. so polishing the serrations was not required.

Thanks OMT. I have heard pros & cons on this BOP seal. I guess I'll try one in this motor under construction.

We have yet to see a seal failure caused by serrations with close to 3000 seals in service. I can count the number of failures on one hand and they have all been traced back to a few key items.

First you must fill the anti-rotation holes on the 3.25 inch seal in both the block and the cap. It is recommended but not mandatory to fill the holes on a 3 inch seal. This is because the 3.25 inch seal is narrower than the 3.00 inch seal and the AR holes are the same size.

Second do not use silicone on the backside of the seal. This can cause excessive lip engagement. The tolerances for lip engagement are designed in and adding silicone changes those tolerances. It’s like making the OD of the seal larger which forces the seal against the crank beyond the optimal sealing point causing friction and premature wear.

If your block has been align bored multiple times or if you are using aftermarket caps. Pay close attention when fitting the seal to make sure that the deflection of the lip from the crank is relatively even. We had one customer’s mains that were bored so far to one side that the lip was smashed on one side and not touching on the other. :eek: It never hurts to check everything!

And finally, 3 inch seals are now in stock again :D