Technical SBC REAR MAIN SEAL LEAK

HAVING A PROBLEM WITH THE REAR MAIN SEAL IN MY CAR
SBC
I HAVE REPLACED IT 2 TIMES AND IT STILL LEAKS
USED FELPRO SEAL BOTH TIMES
STAGGERED THE SEAL
PUT SEALANT ON THE ENDS
AND IT IS NOT INSTALLED BACKWARDS !!
ANY IDEAS ???
THANKS

 

Is the crank grooved from wear? Did you put a sealer such as Permatex Aviation sealer on the area around the seal, where the cap meets the block? Why did you put sealer on the ends of the seal, it is not needed there?

Is it a 400 that has been line honed?

 

I remembered to take a picture of the last one I did, a 327, last month. This one does not leak. Seal is offset about 1/4", no sealer on the ends of the seal, sealer on the block where the cap meets it, crank is in good condition, seal is facing the correct direction.

 

Are you sure it's not the oil pan end-seal that's leaking? Never had a problem with leak's after I switched to the one piece pan gasket's.

 

If using the original style pan gasket be sure you put a dab of sealer on the ends of the wrap around gasket on the ends. Sealing compounds don't adhere well to those nitrile seal ends. It could be washing out. Old style rope seals should be left a bit long (a 16") so the crush will help secure a good seal. Permatex High Tack gasket sealer is the best I've found. The little can with the red goo. A little bit goes a long way. Don't overdo it. The old black Permatex form-a-gasket takes a long time to stop being a liquid. That's not very good for standing up to heat. It tends to run , hence the wash out theory. Fine for cork gaskets, not so fine for rubber, plastics and other non-porous materials. Don't forget to oil the seal lip and/or the shaft when installing.

 

JUST ORDERED A 1 SLIT REAR MAIN SEAL FROM GST
NOT CHEAP BUT SHOULD SOLVE THE PROBLEM
THANKS FOR ALL THE HELP

 

Can you post a link to the part you ordered?

 

GST RACING SEALS
CAN BE BOUGHT FROM FAST FISH AUTO PARTS
IN NORTH CAROLINA
AND THERE IS A VIEDO ON YOU TUBE A GUY INSTALLING ONE ON A SBC REAR MAIN SEAL
NOT CHEAP BUT LOOKS LIKE IT WORKS GOOD

 

@bodymanmp I know you have one of these on your PC, because your screen name is in lower case. Could you do us a favor and press it one time?

 

ok

 

I have seen a poorly functioning pcv system lead to oil leaks. Excessive crankcase pressure will push oil past the seal.

 

That’s the nicest way I have ever seen this brought up.
Well done.

 

Ouch!!! https://www.cometic.com/products/C5379

 

Wondering how it goes in/procedure? Will it fit over the flywheel/flexplate flange?

I guess it does, but not building engines daily.

 

See the split?

 

I don't think you can replace it with the crank in the block, not sure the crank will drop down far enough to let it roll in.

 

I see.
Thanks.

 

Have the mains been reground? If the leak persists, put an indicator on the seal surface and see how much runout you have.

 

This was one of my 1st thoughts as well. That and whether or not it's a mullered up pan gasket relationship.

 

Has it been confirmed that the galley plugs in the back of the block are not leaking ??

 

the galley plugs are not leaking,and i use a 1 piece pan gasket that does not leak,crank looks great also

 

That does look like a much better way to do it........

 

Do you have an update on your ream mail seal leak? Did you get the problem resolved? If so, what did you do?

 

FPP-2900 rear main has it been align honed?2909 if not.

 

Put a Kotex pad under it with magnets like I did. I’m too lazy to pull the engine out! One day I will.

 

I fought a leak on the big block in my Corvette last year. Engine I bought and did not assemble myself. Went through all the steps you have. I finally put sealer between the rear main cap and block. Not a drop since.