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Rear Main Seal

Legs

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I have a 421 with 455 crank bored 60 over with 670 heads and flat top pistons.

When idling, the rear main seal does not leak when I drive it, and oil leaks out of the seal.

I do have a new PCV in the pan going into back of manifold.

Has anyone had same problem and corrected the problem?

I have already changed the rear main seal six times.
 

Pontiac Trans Am

Smokey
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What year of TA do you have?

And six times?

WOW!

We would say something is wrong with the oil pan.

Is the oil pan original?

Thank you,
PTA Staff
 

Hesster

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I have a 421 with 455 crank bored 60 over with 670 heads and flat top pistons.

When idling, the rear main seal does not leak when I drive it, and oil leaks out of the seal.

I do have a new PCV in the pan going into back of manifold.

Has anyone had same problem and corrected the problem?

I have already changed the rear main seal six times.
Unfortunately, the 400 - 455 Pontiac with the rope seal leak can be due to crankcase pressure.

Even with a correct PVC. And especially if the motor is modified for more HP/Torque.

A Viton-based main seal (Butler) will help in most cases.


I finally had it with oil puking on my built 400 T/A motor and installed a Butler Crankcase Evap system.

Expensive, but the problem is solved.

 
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