[TPM]

I think the rear main seal in my 65 389 TriPower might be leaking....do any of those engine oil additives help stop leaks? Any advice would be appreciated

[76TA462]

I had a pesky rear main leak and for me the additive fix did not work. One fix is to slightly drop the crank, enough to replace the rear main seal. If you use the Viton Seal, unlike the rope, you will need to use silicone to fill the 2 holes in the cap.

[TPM]

Thanks. Curious if anyone else has tried the additive and found that it helped....please comment if you did.

[Blued and Painted]

Closely check the oil pressure switch and valve cover gaskets. Any oil leak will end up at the back of the pan.

If it is the rear main seal leak, to what degree. Just some dirty dampness at the rear of engine, making a mess on the floor, or blowing out under the body a smoking off of the exhaust?

I have bought 2 cars dirt cheep because of a leaking 6 dollar oil sender.

[TPM]

It's just a slow leak at this point..oil by the flywheel cover - some drips on garage floor (certainly not leaking profusely to create heavy smoke from constantly contacting exhaust). I will look more closely but I don't think it is the sending unit or valve cover....

[mrrat1]

There is a band aid fix in the Pontiac service manual. You have to remove the rear main cap cut some of the rope seal in pieces and jam it up in there on both sides, silicone and replace the seal in the cap then put the main cap back on.
My old man & I did it in the driveway. It was a PIA but did stop the leak for a couple years. Almost had the engine out by the time we had the oil pan off, was a learning experience for me I was like 16 or 17 at the time. Lots of work and he did lots of cussing....I did a lot of snickering LOL........

[Greg Reid]

I've always been of the opinion that any additive that can stop an oil leak CAN'T be any good for your engine's oil passages. Skip the 'Easy' button and have the leak repaired.
BTW, I had a leak that I was so sure was a rear main...and it did turn out to be brittle and broken valve cover gaskets...both sides.

[pfilean]

Had a leak I was sure was the rear main. Was dripping from the right spot to be one. So I pulled the engine (I wanted to clean things up some anyway) and found the front of the flywheel to be essentially bone dry. So I just put on a new pan gasket and solved the problem. Well - mostly solved. It's hard to get one of these old engines to run as dry as the new stuff with all O ring style gaskets.

[geeteeohguy]

The additives used to soften and expand engine seals to stop leaks are for rubber seals. They will not work for rope type rear main seals. And, they weaken the hard seals that they soften up again, and any other 'good' seal. Do it right, pull the engine, and replace the rear main seal with a quality Viton part. While you're at it, you can detail the engine and engine compartment. I did all of the above on my dirty, leaky, smoky '67 GTO convertible 6 years ago and it doesn't leak a drop....I can drive it 260 miles to visit friends, park in their cement driveway overnight, and nothing....clean as a whistle. I'm just sorry I drove the car all those years before putting up with a huge oil leak. Do it once, do it right, and you won't be sorry.

[hurryinhoosier62]

Originally Posted by geeteeohguy

The additives used to soften and expand engine seals to stop leaks are for rubber seals. They will not work for rope type rear main seals. And, they weaken the hard seals that they soften up again, and any other 'good' seal. Do it right, pull the engine, and replace the rear main seal with a quality Viton part. While you're at it, you can detail the engine and engine compartment. I did all of the above on my dirty, leaky, smoky '67 GTO convertible 6 years ago and it doesn't leak a drop....I can drive it 260 miles to visit friends, park in their cement driveway overnight, and nothing....clean as a whistle. I'm just sorry I drove the car all those years before putting up with a huge oil leak. Do it once, do it right, and you won't be sorry.

Dittos...

[gtofreek]

Also, a PCV system that is not working 100% can cause crankcase pressure to build up, and cause a rear main seal to leak when the problem isn't the seal.

[STEELCITYFIREBIRD]

The only mechanic in a can is the one actually in the schitter.

Oil leaks run down hill, unless it is a pressurized leak or slung by a shaft or fan.

[Half-Inch Stud]

Two high pwrformance way to fix the rear main seal leak

1. add a Vacuum Pump. Anf it won't leak under hard wheel-standing accelerations.

2. limit acceleration to acceptable levels used during grocery gettering, cruises, and car shows.