72 Chevy small block

[Lpeabo]

Can some one tell me how to identify whether I have a one piece or two piece rear main seal? I understand that one of the two requires to either pull the engine or transmission. Which one requires pulling the engine? Thanks

[Tx Firefighter]

A 72 model would absolutely be a 2 piece seal (pull the pan).

[ujsf01]

If memory serves me correct, one piece rear main seals came along at the same time as center bolt valve covers.

[Tx Firefighter]

That is correct.

[MARKDTN]

Originally Posted by ujsf01

If memory serves me correct, one piece rear main seals came along at the same time as center bolt valve covers.

1-pc rear seals began in 1986. Center bolt valve covers started in 1987.

[ujsf01]

Knew it was somewhere in the mid 80s,....but that was a lllloooooonnnnngggg time ago!

[hugger6933]

Seems like only well a few decades ago. Dang that was a long time wasn't it.

[71tahoe]

Originally Posted by Lpeabo

Can some one tell me how to identify whether I have a one piece or two piece rear main seal? I understand that one of the two requires to either pull the engine or transmission. Which one requires pulling the engine? Thanks

Later model 1-piece will require pulling the engine or transmission

Originally Posted by Tx Firefighter

A 72 model would absolutely be a 2 piece seal (pull the pan).

Yep, just drop the pan and rear main cap. I've helped do one but that was 25+ years ago. Used to be a kit with a wire that had a corkscrew end to help pull the new one through.

[jocko]

a sneaky pete is the tool you need to change the upper half of the rear main seal. I've only done it once, will never do it again. Doesn't always go smoothly. The corkscrew is useful, but tends to destroy the old seal, which is fine, but tends to leave scraps. Getting the new one in isn't exactly easy - at least I didn't think it was. So, if you choose to try this, make sure you understand the process first. The sp kit comes with a corkscrew on a string to pull and a seal-profile-shaped pusher to help in removing and sliding the new and old seal around the top of the crank.

[Eddie H.]

Originally Posted by 71tahoe

Later model 1-piece will require pulling the engine or transmission



Yep, just drop the pan and rear main cap. I've helped do one but that was 25+ years ago. Used to be a kit with a wire that had a corkscrew end to help pull the new one through.

I looked in my toolbox, I still have one of those kits with the corkscrew and chinese fingers to pull the new rope seal around with. I also have a dwell meter and point adjusting tool. Dang I'm getting old.

[Wrenchbender Ret]

Those did not use a rope seal. It is a 2 piece rubber seal. Usually you can push the upper part out a little ways & grab it with needle nose pliers. Put a tiny pinch of RTV between the ends and to the outer edge of the cap.

[Eddie H.]

Originally Posted by Wrenchbender Ret

Those did not use a rope seal. It is a 2 piece rubber seal. Usually you can push the upper part out a little ways & grab it with needle nose pliers. Put a tiny pinch of RTV between the ends and to the outer edge of the cap.

Yep, I don't remember exactly what year Chevy quit using rope seals and started using the rubber 2 piece seals. I know that some of the other GM engines still had rope seals into the early 70's

[GASoline71]

Not sure if any of the 350's had rope seals... but the 265, 283, and some 327's had rope seals.

Gary

[Tx Firefighter]

Originally Posted by GASoline71

Not sure if any of the 350's had rope seals... but the 265, 283, and some 327's had rope seals.

Gary

I agree with Gary. By the time 350s came out, the rubber lip seal was in use.