Thread: rear seal leaking need help

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hi i have a 1974 350 with rear seal leak Ive replaced and it still leaks i even off set the seal and its still leaking is there a better seal i could use for a stubborn leak like this. cam plug and oil gally plugs are not leaking and rear seal only leaks when motor is running should i use an offset seal or a double lip seal this motor only has 6 hours on it. and has anyone used these seals if so do you have any part # thanks for the help

Originally posted by 4onthefloor
hi i have a 1974 350 with rear seal leak Ive replaced and it still leaks i even off set the seal and its still leaking is there a better seal i could use for a stubborn leak like this. cam plug and oil gally plugs are not leaking and rear seal only leaks when motor is running should i use an offset seal or a double lip seal this motor only has 6 hours on it. and has anyone used these seals if so do you have any part # thanks for the help

sounds like youve got some other problem. if you have the seal in there right it wouldnt leak. make sure its not in backwards, thats not hard to do. if you know its in there the right way and the seal is ok you need to look some where else. make sure the motor is breathing like it should. oil can run down from the back of the intake or valve cover gaskets and fool you sometimes. the oil pressure switch will leak on chev. sometimes to and run down the back of the motor so it looks like the seal.

I had the same problem as you but on my 400 chev. It turned out to be the rear main seal too. The only problem with it was the engine builder put in the wrong seal-it should have been a align hone rear main seal. Was your Chev 350 align honed? maybe that's it. This seal is just a little bigger. part #720-1962 from Jegs
I also thought it was the rear of my oil pan because it was chrome so I got the one piece fel pro "rubber like gasket" it's reusable and guarateed not to leak. Rear main seal leaks suck. I pulled my engine twice because of it. I now know that you don't have to do that. I just removed my motor mount bolts and jacked up the engine so I had just enough room to remove the oil pan. Sure beats pulling it out completley. hope this helps.

do you have a part # Streets . thanks for the help guys

I just put a 350 in my 78 Chevy monte Carlo and thought the the rear main was leaking as well, but when i went yesterday to get new exhaust from the headers back they noticed that i was coming from the oil sensor on the back of the intake. That was what caused my leak . . .the oil was hitting the firewall and running down the side of the transmission (giving the apperance of a rear main seal leak) It's a quick fix, $ 7.00 at the local Advance Auto Parts Store. That's just my suggestion . . Good Luck.

here what I do....when putting a rear main seal rotate the seal so the parting lines are actually inside the cap/block surface....I push it in till a 1/2 inch hangs past and put a very tiny dab of adhesive sealant on the ends.....lip must be facing front of engine......works everytime.....

Originally posted by 4onthefloor
hi i have a 1974 350 with rear seal leak Ive replaced and it still leaks i even off set the seal and its still leaking is there a better seal i could use for a stubborn leak like this. cam plug and oil gally plugs are not leaking and rear seal only leaks when motor is running should i use an offset seal or a double lip seal this motor only has 6 hours on it. and has anyone used these seals if so do you have any part # thanks for the help

Did you happen to fix this problem? I am having similiar problems but it's not the oil sending unit.

Please advise.

Thanks.

Originally Posted by onemangang

I had the same problem as you but on my 400 chev. It turned out to be the rear main seal too. The only problem with it was the engine builder put in the wrong seal-it should have been a align hone rear main seal. Was your Chev 350 align honed? maybe that's it. This seal is just a little bigger. part #720-1962 from Jegs
I also thought it was the rear of my oil pan because it was chrome so I got the one piece fel pro "rubber like gasket" it's reusable and guarateed not to leak. Rear main seal leaks suck. I pulled my engine twice because of it. I now know that you don't have to do that. I just removed my motor mount bolts and jacked up the engine so I had just enough room to remove the oil pan. Sure beats pulling it out completley. hope this helps.

I hate to dig up such an old thread but I am having the same problem.

I have what looks like a rear main seal leak. I put a dye in the oil and used a blacklight. Looked all around the back of the engine and valve covers. The leak is coming from the back of the engine. Inside where the trans is bolted. It doesn't look like it is coming from the cam plug or oil galley bolts. I put in a Fel-Pro offset rear seal. Still leaks.

My question is the Mr. Gasket part mentioned above, Jegs 720-1962, is for a 400. I have a 350. When I look at what engines that seal fits it only says 400. However when I look at 'stock' seals the 400 and 350 use the same seals. Will the Mr. gasket seal fit a 350? I'm confused.

Bill

Originally Posted by onemangang

Rear main seal leaks suck.

try a ford timing cover leak with a studded oil pan