"66 GT350 Hertz Car Rear Main Seal

[Shelbybo1]

After 3 attempts at replacing the rear main seal on my '66 GT 350 Hertz car; the seal is STILL massively leaking. 
The correct  neoprene 2 piece seal was installed each time.
Has anyone on this forum had a more successful experience with replacing the rear main seal?? or with what is called a "rope Seal" .
Thanks

[tesgt350]

After 3 attempts at replacing the rear main seal on my '66 GT 350 Hertz car; the seal is STILL massively leaking. 
The correct  neoprene 2 piece seal was installed each time.
Has anyone on this forum had a more successful experience with replacing the rear main seal?? or with what is called a "rope Seal" .
Thanks

When I used to change out the two piece seals, I would install the Block side first sliding it around until about 3/8" stuck out.  I would then place the other piece on the Main Cap so the Seal was sticking out 3/8" on the other side so that when installed it slide around the Crank.  This way the ends did not line up at the Cap/Block joint.

[Lincoln tech]

After 3 attempts at replacing the rear main seal on my '66 GT 350 Hertz car; the seal is STILL massively leaking. 
The correct  neoprene 2 piece seal was installed each time.
Has anyone on this forum had a more successful experience with replacing the rear main seal?? or with what is called a "rope Seal" .
Thanks

When I used to change out the two piece seals, I would install the Block side first sliding it around until about 3/8" stuck out.  I would then place the other piece on the Main Cap so the Seal was sticking out 3/8" on the other side so that when installed it slide around the Crank.  This way the ends did not line up at the Cap/Block joint.

That's the way to install them , I hope you are installing the seal with the lip pointing to the right direction ( towards the engine ) , is it definitely the rear main seal that is leaking ? or something else ? Rope type seals require a tool called "Chinese fingers" in order to install , I would not recommend taking that route.

[NC TRACKRAT]

Did you check to be sure that the pin in the rear cap has been removed to eliminate any pressure on the seal?

[Shelbybo1]

To my knowledge, all the above suggestions were followed and implemented.
That is why this is so frustrating and why to next option is to install the the original rope seal used back in '66.

[6R07mi]

seal lip orientation (as previously mentioned ) - critical
rope retention pin MUST be removed ( I assume it's gone or you couldn't rotate the lip seal around the crank )
seal half joint offset from block / cap joint - important
ensure the crankcase is not pressurized

you may need to pull the main cap and inspect the crank-seal journal for nick/damage that is compromising seal lip

look at a prior "leaking" seal lip under a good a magnification and see if you can see any damage to the lip ??

jim p

[Lincoln tech]

What do you mean by massive leak ? Heavy drip while engine running ? Drip after engine shut off ? Did you have a damaged crank in that car ?

[JohnSlack]

The two piece seal that are being sold today NEED to be fitted to your block. The las one I installed was.045" proud on both ends. You place them in the block, make sure that they are fully seated and then make sure that there is only .005" to 0.010" after fitting left proud of the block, then trim the cap end to similar dimensions. Then keeping the cap piece with the cap and the block piece with the block offset each end about 5/16" and place it all together. I clean the ends of each seal and carefully put a small - very small thin coating of LocTite 574 on each seal end and put it together. Use a one piece pan gasket and your done.

[Shelbybo1]

Thanks for all the input. However,
I did not take part in the actual rear main seal installation. I hired it out to shops that do  this type of work  for a living.
I am for certain that the lip of the seal was facing the correct position. I saw pictures of the seal after it was removed the second time.
and the lip position was correct.

[SFM66H]

The two piece seal that are being sold today NEED to be fitted to your block. The las one I installed was.045" proud on both ends. You place them in the block, make sure that they are fully seated and then make sure that there is only .005" to 0.010" after fitting left proud of the block, then trim the cap end to similar dimensions. Then keeping the cap piece with the cap and the block piece with the block offset each end about 5/16" and place it all together. I clean the ends of each seal and carefully put a small - very small thin coating of LocTite 574 on each seal end and put it together. Use a one piece pan gasket and your done.

John,

Can you please share the specifics (brand, part number, sealant, tips, tricks, etc.) of the one piece pan gasket of which you speak?

Thank You!
Kieth

[JohnSlack]

The two piece seal that are being sold today NEED to be fitted to your block. The las one I installed was.045" proud on both ends. You place them in the block, make sure that they are fully seated and then make sure that there is only .005" to 0.010" after fitting left proud of the block, then trim the cap end to similar dimensions. Then keeping the cap piece with the cap and the block piece with the block offset each end about 5/16" and place it all together. I clean the ends of each seal and carefully put a small - very small thin coating of LocTite 574 on each seal end and put it together. Use a one piece pan gasket and your done.

John,

Can you please share the specifics (brand, part number, sealant, tips, tricks, etc.) of the one piece pan gasket of which you speak?

Thank You!
Kieth

Kieth,

It's FelPro part number OS1326OT. They say use it dry, however if you don't trust that a little Ultra Black thinly applied is good.


John

[SFM66H]

Thank You John - much appreciated!!

Kieth

[kram350]

I have seen rear main leaks due to line-bored mains. Has the block be lined bored? Crank moves up in the block and crushes the block seal lip and since the cap has been cut, the cap seal half will sit proud. Have to modify the back of the seal for the block half and shave some off the ends of the cap seal. Tough to do this with the crank in place and get the upper seal lip correct. A one piece seal is the way to go when you can. Doesn't take much for a split seal to leak if the lip is not sitting just right.

[sg66]

Are you positive it's the seal? The 2 large oil pan bolts at the rear are through holes and not blind holes like the rest. If not sealed properly they can be the source of an oil leak that looks like a rear main leak.

[Shelbybo1]

Yes absolutely positive!!
A black light sensitive solution was added to the crank case.
The car was driven several miles. Then area of suspect was scanned with a black light;
yes the leak is coming from the rear main seal.