A/T Pan Gasket Material
Thread Starter
Melting Slicks
Joined: Oct 2013
Posts: 2,569
Likes: 126
From: San Diego California
A/T Pan Gasket Material
Tell me if I'm wrong.
I'm developing an opinion on Composite vs. Cork gasket material for the TH400 Pan.
Had a shop R&R the tranny filter 5 years ago, and they used a blue non-cork gasket. In the last year, a transmission fluid leak developed, dripping from the Converter Cover and FWD LH Pan corner. I thought the leak was coming from the front tranny seal, as I R&R'd the engine a while back and lacked confidence in maybe not damaging it while mating the new engine to it. I took the car to the same shop to "Pull the Transmission and install a new front seal".
They had the car for a few months and it looked like they weren't going to get to it in the near future either, so I brought it home, determined to drop the tranny myself, not trusting any local shops.
When I pulled the TQ Cover off, I found no wetness on the Transmission's front face or T/Q. Front seal must be alright, no? After wiping down the wet joint of Pan to Transmission, the leak appears to be a simple Pan Gasket.
Shop was slow, but at least, honest. 
I believe in cork more than in the rubbery type gasket.
Do you?
Forgive me for this long dissertation on a short question, but thanks for your opinion.
Steve
I'm developing an opinion on Composite vs. Cork gasket material for the TH400 Pan.
Had a shop R&R the tranny filter 5 years ago, and they used a blue non-cork gasket. In the last year, a transmission fluid leak developed, dripping from the Converter Cover and FWD LH Pan corner. I thought the leak was coming from the front tranny seal, as I R&R'd the engine a while back and lacked confidence in maybe not damaging it while mating the new engine to it. I took the car to the same shop to "Pull the Transmission and install a new front seal".
They had the car for a few months and it looked like they weren't going to get to it in the near future either, so I brought it home, determined to drop the tranny myself, not trusting any local shops.
When I pulled the TQ Cover off, I found no wetness on the Transmission's front face or T/Q. Front seal must be alright, no? After wiping down the wet joint of Pan to Transmission, the leak appears to be a simple Pan Gasket.
Shop was slow, but at least, honest. I believe in cork more than in the rubbery type gasket.
Do you?
Forgive me for this long dissertation on a short question, but thanks for your opinion.
Steve
Melting Slicks
Joined: Jul 2006
Posts: 2,291
Likes: 493
From: Salmon Arm, BC
Cork gaskets are crap in my opinion.... any modern gasket is better than cork.
Take a look at your pan cover, and make sure the sealing flange is flat, and not dimpled from tightening the bolts too much
Take a look at your pan cover, and make sure the sealing flange is flat, and not dimpled from tightening the bolts too much
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
Cork is junk...I just passed 205,000 miles on the 4t65E auto in my 01 Grand Prix and probably have changed the tranny fluid/filter 8-9 times since the car was brand new. Still using the rubber/composite GM gasket that came on the car-it's reuseable obviously. Just noticed at the last change that the gasket which is thick rubber with a steel core is beginning to show some dry rubber rot..amazing. Forget cork...1970's material.
Thread Starter
Melting Slicks
Joined: Oct 2013
Posts: 2,569
Likes: 126
From: San Diego California
Good point about the pan's bolt holes caved in a bit. I've never had this pan off to see. Yet. It's the original pan, stamped HYDRO-MATIC, DIV of GMC, so I think anyway it's original. And if so, aren't these pans a bit heavier than the knock-offs?
Appreciate the comeback.
Steve
Thread Starter
Melting Slicks
Joined: Oct 2013
Posts: 2,569
Likes: 126
From: San Diego California
Cork is junk...I just passed 205,000 miles on the 4t65E auto in my 01 Grand Prix and probably have changed the tranny fluid/filter 8-9 times since the car was brand new. Still using the rubber/composite GM gasket that came on the car-it's reuseable obviously. Just noticed at the last change that the gasket which is thick rubber with a steel core is beginning to show some dry rubber rot..amazing. Forget cork...1970's material.
That's a helluva testimonial!
Steve
