How long is a reusable fluid pan gasket supposed to last?

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72
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Phoenix, AZ
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Transmission: GM 4T65E Fluid Pan Gasket: FEL-PRO TOS18717 reusable type After a few thousand miles, a drop of fluid will form on the tip of each individual bolt head. If I wipe the pan clean including all the bolt heads, the next day I can run my finger along the parting surface between the pan and the transmission and get a wet finger. Questions: - If these gaskets are reusable and never wear out, why are there new ones for sale? - At which point do you replace yours? - Do you replace yours with a reusable type, or do you prefer to go with a single use gasket doctored up with sealant? Final comment: Whenever I've used a rubber impregnated cork gasket coated on both sides with Permatex 2B, I've never had a leak. But I'm trying to stay with the OE type gasket because I'm trying stay OE as much as possible. We're supposed to trust the GM engineers.
 
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2,618
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High Tax Illinois
I'm sure they have a put on/take off number until they're no longer usable. That being said I've changed a lot of them and never had a leak. But I've never changed one more than maybe twice. I would think heat would affect them more than being taken off/on. If you changed it out every 50K miles and you had the car 200K miles......3 times. IDK.....
 
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744
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On the road Midwest
I do NOT have an answer for you, but I have personal experience. I currently own 3 vehicles with GM 4t65e transmissions; none of them leak anything, run like a top and 2 have well over 150K. I can tell you that I'm METICULOUS when I've changed fluid, carefully break the seal with a sharp putty knife while one side still has (loosened) bolts in it...Clean the gasket surface with a white linen rag damp with acetone and wipe until a rag comes off still white....Let the pan drip overnight into a drain pan, then swab every drip I can still find underneath...reuse the OEM gasket after wiping it down with dry rags until a white rag comes off white...tighten the pan bolts with an inch pound torque wrench and go around maybe 3 times until no bolts turn any more...I use no permatex or any sealer, it's not used OEM... I have NO leaks, seeps, dry bolts a week or month later....Now all this being said, I prefer to change ATF after ~30K miles based on MolaKule's answer here: https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/2605356/2 I'm also a fan of ZZPerformance and have their 4t65e pan with drain plug on 2 of 3 vehicles: https://zzperformance.com/collections/3800/products/4t65e-aluminum-transmission-pan It's so much less mess, but still drop the pan every other fluid change to swap filters. I think the car my daughter drives has had 4 fluid changes, OEM gasket...I've not replaced a gasket.
 
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34,412
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NY
As long as the gasket retains its shape and has no tears or deformities it can be used again. I got 3 uses out of the transmission pan gasket on my 2000 Century before we gave the car to my son.
 
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4,194
Location
Parts Unknown
Originally Posted by Ihatetochangeoil
I do NOT have an answer for you, but I have personal experience. I currently own 3 vehicles with GM 4t65e transmissions; none of them leak anything, run like a top and 2 have well over 150K. I can tell you that I'm METICULOUS when I've changed fluid, carefully break the seal with a sharp putty knife while one side still has (loosened) bolts in it...Clean the gasket surface with a white linen rag damp with acetone and wipe until a rag comes off still white....Let the pan drip overnight into a drain pan, then swab every drip I can still find underneath...reuse the OEM gasket after wiping it down with dry rags until a white rag comes off white...tighten the pan bolts with an inch pound torque wrench and go around maybe 3 times until no bolts turn any more...I use no permatex or any sealer, it's not used OEM... I have NO leaks, seeps, dry bolts a week or month later....Now all this being said, I prefer to change ATF after ~30K miles based on MolaKule's answer here: https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/2605356/2 I'm also a fan of ZZPerformance and have their 4t65e pan with drain plug on 2 of 3 vehicles: https://zzperformance.com/collections/3800/products/4t65e-aluminum-transmission-pan It's so much less mess, but still drop the pan every other fluid change to swap filters. I think the car my daughter drives has had 4 fluid changes, OEM gasket...I've not replaced a gasket.
A big term paper for a couple simple questions which really didn't get answered..
 
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7,824
Location
Champlain/Hudson Valley
Would the OP please provide a description of the gasket? There's "almost paper" looking stuff. There's formed black neoprene on a metal frame There's the crushed cork and black stuff (mentioned above) There's a blueish one I just got with my Hastings TF110 filter kit (for a Ford 5R55E) My term paper will about finding "whatever" after 15 years.
 
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3,977
Location
Central Virginia
The reusable gaskets look like a stiff gasket with double "o-rings" around it. I don't think any other type are considered reusable. Differential pan gaskets can be like that too. I've never had one leak, but for about 30 bucks or a little less you can replace it. Make sure your pan is flat with a straight-edge around the bolt holes.
 
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4,623
Location
Suburban Washington DC
Originally Posted by perfect_oil
- Do you replace yours with a reusable type, or do you prefer to go with a single use gasket doctored up with sealant?
I toss the reusable type and replace with RTV. That's what most of the manufacturers have switched to for no leaks or seepage.
 
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4,086
Location
Texas
Originally Posted by Silverado12
Make sure your pan is flat with a straight-edge around the bolt holes.
That was one point I was thinking about . If the bolts are over tightened , the pan , metal around the bolt holes , may become distorted . And not seal correctly .
 
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72
Location
Phoenix, AZ
Thread starter
Originally Posted by Kira
Would the OP please provide a description of the gasket? There's "almost paper" looking stuff. There's formed black neoprene on a metal frame There's the crushed cork and black stuff (mentioned above) There's a blueish one I just got with my Hastings TF110 filter kit (for a Ford 5R55E) My term paper will about finding "whatever" after 15 years.
It's a steel shim encapsulated with with rubber. It also has plastic grommets in the bolt holes to prevent over tightening.
 
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9,915
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USA
I don't know. I just drain with the drain plug smile The good news is that Dorman makes an aftermarket transmission pan for your 4T65E that has a drain plug, making future ATF changes much easier, so you will never have to worry about reusing the gasket again smile
 
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1,224
Location
Indiana
Originally Posted by atikovi
Originally Posted by perfect_oil
- Do you replace yours with a reusable type, or do you prefer to go with a single use gasket doctored up with sealant?
I toss the reusable type and replace with RTV. That's what most of the manufacturers have switched to for no leaks or seepage.
GM proved in the 80s (via a ton of warranty cost) that RTV (even applied by robots) is a poor substitute for a good gasket design.
 
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1,224
Location
Indiana
Originally Posted by perfect_oil
It's a steel shim encapsulated with with rubber. It also has plastic grommets in the bolt holes to prevent over tightening.
At Allison we determined that's the right way to go with a stamped pan...except the crush spacers need to be steel to be durable and take the load. Of course the elastomer has to be good stuff to take the heat. These days China can produce many kinds of substandard quality.
 
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4,623
Location
Suburban Washington DC
Originally Posted by nascarnation
Originally Posted by atikovi
Originally Posted by perfect_oil
- Do you replace yours with a reusable type, or do you prefer to go with a single use gasket doctored up with sealant?
I toss the reusable type and replace with RTV. That's what most of the manufacturers have switched to for no leaks or seepage.
GM proved in the 80s (via a ton of warranty cost) that RTV (even applied by robots) is a poor substitute for a good gasket design.
Can't compare 80's chemistry to today.
 
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72
Location
Phoenix, AZ
Thread starter
Originally Posted by atikovi
I toss the reusable type and replace with RTV. That's what most of the manufacturers have switched to for no leaks or seepage.
What do you think about the new 90 minute Permatex RightStuff? It comes in a regular squeeze tube and is more economical than the expensive aerosol cheese wizz can.
 
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