I had oil leaking from the back of my engine close to where the trans meets the block. I'm doing a head job so I have everything off and want to replace the o-ring on the oil pump drive because I have heard that this could be the culprit for the leak in the 3.4L motors. Does anyone know the part # for this o-ring or where I could find it?

 

More than likely you have a rear main seal leak, as I did on my old 3.4L. How many miles on the car?

 

I think he means where the distributor would go? Theres a cap with a gear drive connected to the oil pump iirc. I had to go to my local gm dealership for the o-ring that went around the shaft itself, and I used a small block chevy gasket that sealed it to the block deck.

 

If its coming from the back like that im gonna have to agree its your rear main seal. Sometimes they can be a pain the a$$ and not fun to do.. I havent done one on this motor so I couldnt tell you everything about it.

If you want to do it your can find them for cheap on www.rockauto.com nothing fancy just replacement parts