# Rear Main Seal R&R



## 69Chrgr (Jan 4, 2017)

Hey Guys

New to Pontiacs as I have a customer with a beautiful 67 GTO with a 400 that will require a rear main seal replacement. After reading through several posts it's obvious (and after looking under the car for myself) that I will need to pull the engine to properly perform the job. I purchased a Viton 2 piece seal from Summit. Just curious however, do I need to remove the main caps to lift up on the crank to replace the rear main seal, or can I just turn the motor over to and snake the upper piece in to the block? I've done Olds 455's this way, however this is my first Pontiac. 

Many Thanks, 
Darren


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## GTO JUDGE (May 14, 2005)

69Chrgr said:


> Hey Guys
> 
> New to Pontiacs as I have a customer with a beautiful 67 GTO with a 400 that will require a rear main seal replacement. After reading through several posts it's obvious (and after looking under the car for myself) that I will need to pull the engine to properly perform the job. I purchased a Viton 2 piece seal from Summit. Just curious however, do I need to remove the main caps to lift up on the crank to replace the rear main seal, or can I just turn the motor over to and snake the upper piece in to the block? I've done Olds 455's this way, however this is my first Pontiac.
> 
> ...


Not necessary to remove the engine with the TH400 not sure about manual. It can be done by jacking the motor up to gain access. A club member's '67 was done this way with a 2 piece vitron seal, and my '70 was done this way with a 2 piece vitron seal. Once the seal is installed it must sit for a day or so for the permatex to set up. If not allowed to properly set up you stand the chance of leaking.


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## 69Chrgr (Jan 4, 2017)

Thanks GTO Judge. That's good to know regarding the engine removal. So the oil pan will clear the oil pickup by lifting the engine? I have a lift, transmission jack, etc. Some folks here mentioned having to remove the timing chain, loosening the main caps, and lifting the crank to properly install the upper seal half. Thanks again for the prompt reply.


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## GTO JUDGE (May 14, 2005)

69Chrgr said:


> Thanks GTO Judge. That's good to know regarding the engine removal. So the oil pan will clear the oil pickup by lifting the engine? I have a lift, transmission jack, etc. Some folks here mentioned having to remove the timing chain, loosening the main caps, and lifting the crank to properly install the upper seal half. Thanks again for the prompt reply.


You'll need to jack the engine up to remove the oil pan yes. You may have to remove the transmission so you have room to work. I would recommend a one piece oil pan gasket when replacing it and reinstalling the pan. Ames sells it. It's neoprene and only 2 areas gets a dab of RTV. You won't have to mess with the old style where it had to be pieced together giving multiple possible leak points. There are others on here familiar with the installation process than can aid you in which parts to remove.


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