SB rear seal leak question

[Fishracer66]

OK, Small Blockers, maybe somebody here has a solution for me!

A while ago I had a race 340 built for my Barracuda out of the modern 4 bolt main "Resto 340" MP block, and an early style forged crank. My builder told me that the early and later Mopar small blocks and cranks used different types of rear crank seals, and he installed the latest type crank seal in this engine, despite the early crank. "It might eventually leak", he said. So, a couple of years and a few road races later it appears to be leaking, pretty profusely.

Anybody else running this mis-match of crank and block, and how did you solve the rear seal problem? I hope you don't tell me to change the crank! :banghead:

Thanks;

Mike
Scappoose, OR

 

[Rapid Robert]

He might of been referring to a rope (OE) seal or the common neoprene? black rubber (ish) seal. The crank serrations can make a neoprene seal leak over time. Car quest has the rope seal kit #JV551 (iirc) and the black seals are commonly available. With it leaking profusely you'd likely have to pull the pan and you can drop the crank a hair in the vehicle by loosening the main caps so you can get to & replace the upper seal half along with the lower seal half of course. First see if it is the rear pan seal that is leaking

 

[krazykuda]

I've always had good luck with the rubber style rear crank seal.

The early style used the rope seal. Either seal will work, it depends on what you are comfortable with.

You have to install them properly, but eventually every rear main seal develops leaks with high mileage...

 

[AJ/FormS]

Have you given any thought to crankcase pressure/venting?

 

[Rodzilla]

What AJ said,,,you got a good breather and Pcv installed? Crankcase pressure can push oil past what would have been a decent seal. I've done that to myself before.