My th400 pan gasket leaks, how do I stop it?

I have tried to replace this gasket 4 times now. I have a brand new pan, and I always torque to 8-10 foot pounds. From the looks of it, it leaks down the bolts somehow. I always see the oil welling up on a couple of bolts. I have tried rubber, cork, and fiber composite gaskets. I never use rtv or any sealant as it is not recommended, but I am about ready to put some on out of desperation, just have to be careful not to let it squeeze out to the inside of the pan. It is not a huge leak, but it frustrates the hell out of me that I cannot seem to stop a simple leak, and I am tired of seeing that oil on my garage floor. And it is only ten bucks for a new gasket so every couple of weeks I'll try again, and I'll probably be trying again this weekend too.

If anyone has experience with this give me a clue.

H.

Reply to
-the HoSt-
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Too much torque. You're smashing the gasket.

60-65 inch pounds is more like it. If you're using a 3/8 drive torque wrench, you don't have the accuracy needed at the lower range of the scale, get an inch pound torque wrench.
Reply to
aarcuda69062

Reply to
-the HoSt-

I'll try that next time.

thanks.

Reply to
-the HoSt-

====== ====== I disagree...........

He's either got a Chrome pan......... or the bolt holes are PUCKERED...(i doubt that one)...... or the leak IS NOT a pan gasket leak.

there ......i said it.......now i feel better.

:)

~:~ MarshMonster ~takes a sip of his crownroyal..........mmmmmm...good stuff~ ~:~

Reply to
Marsh Monster

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Install a aluminum pan.

Reply to
TOBMA

That's not disagreeing, that's other possibilities.

10 ft.lbs. -is- too much The bottom range (20%) of a 3/8" torque wrench, any torque wrench is not very accurate
Reply to
aarcuda69062

=========== ========== He said it was likely pan bolt torque............

I said it wasn't.

~:~ MarshMonster ~takes a toke......disagrees that it's not disagreeing~ ~:~

Reply to
Marsh Monster

Who he? Certainly wasn't the original poster.

I said it was. Got it now?

Reply to
aarcuda69062

It is entirely possible that when the Chinaman punched this pan he was worrying about his tea ration being cut back if he didn't punch out

5000 that day.It wasn't done right and there is a flaw. I would check it carefully with a straight-edge over each hole and look for any splits. Look above the leak area for a higher leak (already mentioned in thread),and if it still leaks with the correct torque which BTW is 12 (TWELVE) Ft. Lbs.according to the GMC shop manual in front of me,then please re-post.
Reply to
brianorion

Wow, nice to see the passion guys LOL!!!

Well it IS a chrome pan, Marsh Monster mentioned that. And the holes aint puckered. I have a Haynes manual and it says 10, I do have a inch pound wrench and I get it to 120 inch pounds actually. I have never gone crazy on it and tried to torque it down to 30 foot pounds. If I seal it up and fill it up, it does not leak. If I go for a drive, get the fluid hot, check the fluid level to make sure it is just right then park it, it still does not appear to leak for quite some time. But the next morning... %&$*ing leaks. I figure if it were a leak somewhere else it would be evident soon after driving and bringing it up to temp then parking it, but it waits about 6 to

8 hours.

Thanks for the info. H

Reply to
-the HoSt-

formatting link
Install a aluminum pan.>

Damn that's an expensive pan. I see that it comes with washers for the bolts, maybe I need that.

H
Reply to
-the HoSt-

also coat both sides of the new gasket with vaseline,,,,,,,,,worked for me.

Reply to
lildevil

Clean the pan and all around the transmission real well. Then clean the pan and gasket surface real well and install a new gasket with a bit of high tac on it. Torque it down and then fill it up with fluid. Now take some baby powder and dust around the gasket and around any seal point (TV cable, shift shaft, dip stick tube and such). Then take it for a drive and see where the powder gets damp. That will tell you where the leak is. Once your done just take it through a car wash and clean it up.

Reply to
Steve W.

My own two cents worth, I once had a TH400 that I swore was leaking through the pan gasket. After I replaced it twice, I found out the dipstick tube o-ring was seeping and running down appearing like the oil pan gasket was leaking. Another common place to look on those trannys is the modulator valve.

All this is especially true if the gasket seems to always leak on the right front of the pan gasket!

Reply to
Doug Adams

Amen to that. Same for the TH350.

Al

Reply to
Big Al

==== ====

you're wrong.....i'm rite.....

undertand??

:)

~:~ marsh ~sips his shroomjuice~ ~:~

Reply to
Marsh Monster

========= ========= BEST ADVICE AWARD!!

but then.......i reeely wasn't after it.......i've got plenty.

:)

~:~ marsh ~takes a toke......goooooooood stuff~ ~:~

Reply to
Marsh Monster

========= =========

I'll tell YOU how to permanantly......(did i spell that rite cuda?).. stop that leak........

if you'll post for all to see.........

that I...me alone...all by meself.......ama freek'n REPAIR GAWD.

yep..i will......promise.

anywhoooooooo......... did i mention......i jest recently....... left......... the tranny biz after 18 years in it..??

no...? oh...ok.

:)

~:~ marsh ~takes a sip of his crownroyal..packs his pipe....~ ~:~

Reply to
Marsh Monster

======= =======

nope..that's not what you need......

you need sealant.

:)

ok......so you didn't post that i was a freek'n Repair Gawd...

i told you anywhoo..

:)

~:~ marsh ~drops another shroom in the boiling pot......mmm..... goood batch~ ~:~

Reply to
Marsh Monster

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