pop23235

Recently there was a post that referred to instructions from one of our noble mechanics about the application of sealant on the rear main seal to prevent the Harley symptom. Does anyone recall? Search doesn’t help on this one.

Robert61

Don't know if this is what you are talking about but maybe. I'll refrain until you confirm.



https://www.corvetteforum.com/forums...d-attempt.html

pop23235

Robert, that’s it. Getting ready to install the rear main seal, usually don’t leak, but I can always learn something better

Robert61

I did engines professionally for many years not just an occasional build. I always learned from my or others mistakes. What I suggested to Mark and what I always do is coat the inside groove of the seal with Permatex Ultra Black. Put grease on the seal lip for lubrication on start up. After the seal is installed silicone around the rear face of the seal to the block and just smooth the seal block area. I normally use the blue Fel Pro seal. It's obviously more difficult to do if the engine is in the car. In that case you would clean as well as possible do the upper as best you can and do the cap as described. I'm not a believer in offsetting the seal to the block and cap, GM didn't do it and I think they know a thing or two about seal installations. No matter what you do it's a seal that's been cut in half and that was never a good idea.

pop23235

Think I got that. I use ultra seal on the backside of the seal to keep oil from going around the seal and a smear on the parting line. I can extend that a bit more into the inside. Split seal is damaged by design. Never been much of a fan of silicone sealers as it can’t be controlled and often swells and destroys it’s bond, but will look at the rear edge after assembly. Thank you.

Robert61

I can't speak for all silicone sealants but UltraBlack certainly doesn't do that. I had a friend that used blue silicone and the contact with oil would destroy the silicone. He used it because it was the same color as his car.


Most people, all should, use silicone for the end pads between the block and intake. If there was an incompatibility it would show up there for sure as you are filling a gap of 1/8". On the rear main you are just trying to insure there's no leak path. I would add you should smear a small amount across the cap block interface. That's another over leak path, the area between the rear main seal and where the oil pan seal goes.

mpate

My seal is still leak free. This is the first time since I have owned the car that I have not had a spot of oil on the floor when I moved the car. I used the Fel Pro 2912 but I quite sure the blue seal would have worked

Good Luck—-Mark

Barry's70LT1

A picture is always good.

pop23235

You are correct, I’d forgotten that Ultra Black is silicone. It’s the blue I avoid.I still use the GM seal for the waterfall, IF the drilled holes are present. I do the smear as suggested and shown in Barry’s post, plus the back side of the seal against the block. The downside is that upper seal cannot then ever be changed in the car.

inspectorudy

My mechanic just installed a Felpro seal that recommended offsetting it. He said he has had very good luck with this setup. He did put sealant on the seal ends and the flats where the cap goes. It has run a few miles so far with no leaks. The seal that was put in a year ago leaked like it was twenty years old. When the mech took it out, he said it was flush with the metal joints. I do not think GM got it right on a lot of things and newer approaches can be taken on some things. Weren't the OEM seals rope? Anyway, this is the first time I haven't had a puddle under my car.

pop23235

I think the rope seal goes back a bit further, but I remember doing one that actually didn’t leak. It’s a wild guess to cut the rope long so it compresses enough not to leak and not too much to prevent the main from complete seating.

wellstroked

Felpro BS 11829-1

Installed with engine in car, sealant was Permatex high temp silicone. Dry as a bone.

1969RAY

I saw a post that used a one piece seal. As I recall, it was cut in one place with a razor blade, then fed around the top of the shaft. Once there, the cut end was siliconed and pushed to the top by rotating the seal. Seemed like it would be worth a try.