[z06gto]

I have a rear main leak on my newly rebuilt 421 in my 66 GTO. The oil is not pouring out but will puddle when parked.
I am wondering, can I fix this with a "stop leak" additive to the oil ?
If I have to drop the pan to replace the seal can this be done in the car or do I have to pull the engine ?
Any advice would be appreciated.
Thanks

[wheelspin]

Welcome to the leaking rear main club .

Stop leaks are not effective for rope or viton main seals and are a waste of money. Yes, you will have to pull the pan; and yes, pulling the engine is the way to do a proper job. If you didn't install the BOP viton seal, now is the time.

Les

[z06gto]

I thought that was going to be the answer, but I thought I'd ask anyways. He installed the rope style seal. They keep telling that it may seal in time once the rope material swells, true ?
What is a BOP viton seal ?

[z06gto]

wheelspin I sent you a PM.
Thanks

[wheelspin]

The viton seals are available from our host: Performance Years, and properly-installed, are recognized as superior to the current non-asbestos rope seals.

Les

[Wade Congdon]

Give me a call 920-728-2388. I will help you through this problem.

[z06gto]

Will do thanks.

[hal101]

did you read this thread

i didn't know you wer to put RTV on the rear main


http://216.178.81.108/forums/showthr...=rear+main+rtv

[mwritter]

Can you request that your engine guy do the labor? Sounds like he screwed up. My appologies if you built your own engine.

[BVR421]

Z06 how did you determine its the rear main seal that is leaking? there are several other leak possibilities that end up dripping to the floor directly under the rear main
just like antifreeze leaks, oil leaks are not always where you see the puddle

[z06gto]

BVR421, good point, I will check all areas before pulling to replace the seal. It really looks like it is coming from the rear main.

[OINK 1]

I off a pre-fitted neoprene seal, much tougher.

comes with installation video $40.00

Thanks,
Pontiac Gregg
1-303-776-0877
Colorado
Visa, M/C

[Cardo]

O6gto, follow the earlier link and look at the photos of my 389. Putting the bead of RTV (as the shop manual states) took care of my leak. I've had rope seals and a BOP seal in this motor and it always leaked on me. Since i did this i have driven the car 200 miles and it has not leaked a single drop of oil. If you look closely at the pics you can see the block dips down ever so slightly between the pan rail and where the dowell is in the block , almost like the block wasn't resting flat on the mill when it went across. Pontiac must have known there was a problem like this otherwise why would have they instructed in the shop manual to put a bead of sealer there? As many times as i have read that manual i never noticed it, but there is a single sentence in the shop manual instructing you to put a bead of sealer from the edge of the rear main seal across to the oil pan gasket. I suspect that there are hundreds of others chasing this same type of leak, but not putting sealer under the main cap. I too was always told to never put anything at all under a rear main, but i have talked to some of my friends that are into Fords and Ford also instructs to put sealer under the cap. Give it a try, after my experience i'm confident that this will take care of it.

[ks gto (Cap)]

My 421 was also leaking a small puddle when shut off. Replaced the rope seal that had 8000 miles on it - Put in the Vitron Seal and it's been bone dry for a year. Cap

[z06gto]

Thanks, I am going to pull the inspection cover of this weekend and look things over very closely.
I appreciate all of the input.

Thanks again.

[68ragtop]

From what I know the older rope seals had asbestos in them, & of coarse
today, that would kill you instantly upon installing it. (kidding) so they are not the same anymore. I know the "newer" rope seals can leak if not installed perfectly.

I have used BOP seals & I have had no leaks. Just be sure to install them correctly, & make sure the crank is not goobered up in that area. The machine shop usually will not touch the oil seal journal. I had mine polished for a better fit. there are still oil collection grooves on that area, but not enough oil will escape to ever cause a problem.

68RT

[z06gto]

I drove my car about 100 miles and double checked all bolts and other leakable areas. After a 25 miles trip I crawled under the car and oil was everywhere.
So I pulled the engine this past weekend. I picked up a B.O.P. seal and will install this weekend. Thanks for all your help. Wade at B.O.P and Pontiac Gregg gave me a lot of good advice and information. Thanks to all.

[quicksilver97ta]

Let us know how you do. I havn't seen a thread on this lately so it's good reading to see how well others do. I know I'll be doing this eventually.

[z06gto]

I'll keep you posted on the out come. Of course I was not a happy camper taking everything apart, but the motor rebuilder is a good friend of mine
Needless to say he feels bad and will fix me up !

Thanks

[z06gto]

My motor guy called yesterday and told be they got the engine apart and said the rope seal was shot. He said it looked "real bad" and there were "issues". The leak would have gotten real bad, real quick. Needless to say my friend that runs the shop was not happy with his engine assembly guy and will be paying for all cost. I told him most of the cost will be in all the beer we drank .