Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (
-   Transmission - Rearend (
-   -   Transmission leak (

Bobs36ford 09-23-2012 08:15 AM

Transmission leak
I have a 350 turbo chevy trans in my 36 Ford. I am going nuts trying to stop trans leak. I've changed the manufactures gasket three times myself then bought an aluminum pan changed gasket again ...still leaked.

I finally took my car to AAMCO they changed gasket and it still leaked with aluminum pan. I then decided to let AAMCO try with manufactures gasket.....guess what , it still leaks.

I've tried cork gaskets and rubber gaskets. I've put a metal ruler on trans to make sure its true and its OK.

Any ideas?


RWENUTS 09-23-2012 08:43 AM

Have you checked the vent?

Crosley 09-23-2012 09:37 AM

You either have a crack at the pan rail for the leak at the pan or it is not the pan leaking. Oil can leak from one location , then travel around the edges to drip off some place away from the actual leak

454 Rattler 09-24-2012 09:06 AM

I thought you would get more answers than this.

These transmissions have a habit of leaking if they sit unused for a while.

I would suggest that you wipe it off and take it for a short ride, then re-check to see if it's the gasket or some place else.

Good Luck !


prostreet6t9 09-24-2012 02:04 PM

Check the manual lever seal and the accumulator.... Both are common leaks and when they do it can look like a pan leaking.

Cape Cod Bob 09-24-2012 08:02 PM

I went thru the same problem/. I also changed to alum pan and provided gasket. I torqued it properly. Do not over tighten. Next common leak is dipstick tube. Be sure you havre the correct tube for the tranny. It will take either an "O" ring or the top hat plastic type. Be sure your dipstick tube is supported and be sure it is in the correct position. This can be a tuff one to find as the kick down cable is near the dipstick hole and it can leak also.
The speedometer hookup is another culprit and on mine I finally figured out that the brand new driven gear was letting fluid past it. You can get a new bullet to with a new "O" ring for it.
And lastly on my tranny filling it to the full mark was to much fluid. I let it run a little lower and it is better.
All these places leaked on mine after a rebuild. I would go for a cruise and come back and crawl under and look to see where the leak was.
Plus of course I had to wipe everything off . , . Finally got them all.:welcome:

rusty duck 09-24-2012 09:24 PM

transmission leak
What is the correct torque on the TH 350 transmission? Mine also leaks just a bit.

Ruthlessmr 09-24-2012 10:30 PM

is this the same one that had a vibration ?sounds like the pump seal and bushing might be shot

rusty duck 09-24-2012 11:20 PM

Transmission Leak
Not the same. Mine just leaves a few drops on the garage floor and I thought I might not be torquing to the correct spec. Just want to know what the correct torque is for the TH 350 tranny pan bolts.
Rusty Duck

Irelands child 09-25-2012 05:05 AM

I have a Ford C4 and have gone through the pain. Transmission pan gaskets - cork leaks!!! There are several different kinds of fiber gaskets plus at least one manufacturer that supplies a steel in rubber version Moroso 93102 - Moroso Transmission Pan Gaskets - Overview - and not inexpensive, but they work. Those pan bolts - if they are conventional bolts and washers without an integral washer( flange head * ) - they leak. I'm using them as well as sealing washers** at 12 lb ft of torque. These DO NOT leak. Then there are Lokar dipsticks - the ones with a single 'O' ring can leak a lot. The 'improved' double 'O' ring version will leak less - Lokar uses the wrong diameter 'O' ring, at least for my C4. Lokar will either repair or replace that single ring dipstick for the price of postage one way - they sent me a new one. I'm now using a locking Hughes dipstick which has a GM type seal that does not leak.

* Flange head - McMaster-Carr

** Sealing washers - McMaster-Carr

As far as pans - all pans are not the same - I went through 3 new stamped steel, including a NOS Ford and now have a Trick Flow aluminum version where the bolt holes wont bend out of shape at normal torque tightness - here's one for the TH350 Trick Flow Specialties Automatic Transmission Pans - TH350 Transmission Type - Search Results for transmission pans -

Did the leak stop? No but it went from a pretty good sized puddle in 3-4 weeks to a couple of spots and my guess is that I have a minor seal leak.

Did I say that I went through the pain with the pans????:pain::pain:

Dave W

PS: If this fails, there are bigger problems with that transmission - seals, cracks (tailshaft with a TH350 seems to be not uncommon')

rusty duck 09-25-2012 10:07 AM

transmission leak
thank you for your reply. maybe a couple of drops over several weeks is not enough to worry about. I'll re-torque to 12 lbs and see what happens.
Rusty Duck

Cape Cod Bob 09-25-2012 05:58 PM


Originally Posted by rusty duck (Post 1593688)
What is the correct torque on the TH 350 transmission? Mine also leaks just a bit.

Haynes says 10 ft.lbs.:welcome:

Ruthlessmr 09-25-2012 06:31 PM

It might be opinion but i have had great luck with the cork style gaskets
I use a t handle and retighten them when its hot and usually that seals them all

SSedan64 09-26-2012 01:32 AM

X2 on the retighten/retorque. 2-3 times is usually needed. Some Trans pan holes go into the fluid at the bracket mount area & sealant is needed on the threads.
Cork is best for stock Pans with raised bead flange.
Duraprene is also great, they're reusable.

Merkur87 09-26-2012 05:44 AM

Try to avoid cork gaskets if at all possible. Most are synthetic cork and fluid will bleed through the material itself.

Maybe the problem is not the gasket at all. It could be a torque converter seal leaking, dipstick tube, or cooler line fitting. This can easily be assumed to be a pan gasket leak.

All times are GMT -6. The time now is 03:51 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.