# Rear main seal



## Tiger Joe (Aug 18, 2021)

ive searched and searched and all I have done is confuse myself. I come from big block chevys so I’m not familiar with all the ins and out of the Pontiac rear main 

70 455. Never apart completely stock. I bought a Viton seal from Tin Indian before reading everything on here and now I’m second guessing myself. I have the engine out on a stand. I really want to get this right. 
what’s my best shot? main things I see mentioned are BOP viton seal(would think the tin indian I bought is similar to this) and the improved rope seal From best gasket. 

at this point I’m leaning toward the improved rope seal but am unsure


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## RMTZ67 (Mar 12, 2011)

Tiger Joe said:


> ive searched and searched and all I have done is confuse myself. I come from big block chevys so I’m not familiar with all the ins and out of the Pontiac rear main
> 
> 70 455. Never apart completely stock. I bought a Viton seal from Tin Indian before reading everything on here and now I’m second guessing myself. I have the engine out on a stand. I really want to get this right.
> what’s my best shot? main things I see mentioned are BOP viton seal(would think the tin indian I bought is similar to this) and the improved rope seal From best gasket.
> ...


I used the rope seal wit no issues but the viton seal seems to be popular here.


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## PontiacJim (Dec 29, 2012)

Read this older post. It's all about the serrations on the crank where the seal goes. If too rough, it can eat up the Viton seal. You can smooth them down for the Viton seal. If you use the Best brand graphite seal, you don't have to do this. The Viton will work fine if the serrations have been smoothed down a bit and you follow the installation instructions.









1969 GTO rear main seal replacement


Morning GTO Guys, It appears I have a rear main leak which started sometime after the last oil change in late March this year, I just noticed after a long drive last weekend, the motor was completely rebuilt 4 years ago, seems a little strange it started now, although maybe not. Anyways very...




www.gtoforum.com


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## Boomstick (Sep 13, 2021)

i just had mine done on my 69, they used the felpro and so far no leaks at the rear main... 

i do have one dripping onto the right header at the collector but thats got nothing to do with the rear main... i think this new one is the oil filter adapter. once the arctic weather goes away here ill look more into it but for right now shes on winter vacation...


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## Tiger Joe (Aug 18, 2021)

PontiacJim said:


> Read this older post. It's all about the serrations on the crank where the seal goes. If too rough, it can eat up the Viton seal. You can smooth them down for the Viton seal. If you use the Best brand graphite seal, you don't have to do this. The Viton will work fine if the serrations have been smoothed down a bit and you follow the installation instructions.
> 
> 
> 
> ...



Yes I've read about the serrations, thats one of the things that has me concerned. I havent pull my pan yet, but being my engine is bone stock, Im guessing im 100% guaranteed to find serrations, just a question how rough they are. thats another thing that has me leaning toward the graphite rope seal. 

for what the rope seal costs, i may just order it to have both on hand.


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## Tiger Joe (Aug 18, 2021)

Update- finally got around to pulling pan. I ended up going with the graphite rope seal. With the serrations on the crank I didn’t want to chance it tearing up a Viton seal.


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