TXjeepTJ

iTrader: (8)

It seems every transmission pan I install (twice on 4l60e, and now a 4l80e) leaks heavily. I follow the proper torque sequence and proper torque values, but they all leak - some even leak A LOT. I've used rubber and cork gaskets, both giving the same results... Initially they don't leak, but as I drive it and let it sit in the garage it starts leaking more and more.

Any tips? Wth could be going wrong?

RPM WS6

iTrader: (3)

Perhaps the torque wrench isn't calibrated well.

I've never once used a torque wrench for a trans pan, and the worst that's ever happened was a minor seep from one or two bolt heads after the first heat cycle. A slight re-torque has always corrected this with no issues.

So either:

A) You have significantly under-torqued the bolts and tightening it up further will stop the seepage.

or

B) You have significantly over-torqued causing the gasket to split/distort, thus requiring a new gasket.

In either instance, something isn't right with the torque wrench if you're following factory specs and getting these results.

BMR Sales2

iTrader: (40)

Are you using the cork or paper style gaskets? I do whatever I can to stay away from the cork gaskets as it is very easy to over torque them which leads to leaking issues.

RockinWs6

Usually its not the pan gasket leaking in the 1st place, could be any number of connections including the dip stick tube. The fluid runs downs and collects around the pan so it looks like the gasket is leaking. Look around above the pan to see what looks wet with trans fluid.

diaz90220

you might have over torqued the pan at one time and might have warped the pan, if you have a straight edge you can see it or a metal ruler to check the gap, the pan is a thin it warps easy. replace pan or straighten it out.

Burken01

iTrader: (88)

First off which pan is it, stock stamped steel?

If so then it's warped around the bolt holes, they need to be hammered flush.. And even then it might not be straight..

I went to a tci aluminum pan because it has thick flanges like our oil pans do and I didn't want to play around with the stock pan too much..

TXjeepTJ

iTrader: (8)

Thanks for all the tips guys. I've used both rubber and cork gaskets with bad results. I will check the pan to see if the bolts are flush - all the pans have been the stock stamped steel pans.

Used two different torque wrenches w/ same results - I'm starting to think it is the pan

Burken01

iTrader: (88)

what are you torquing to?

Should be 10-12ft lbs

RPM WS6

iTrader: (3)

Did the pans leak before you removed and reinstalled them? If not, then any issue is the result of an under-or-over torquing situation on your part and not a previously damaged pan. If this has happened with several pans (no leaks before, then constant leaks after you have R&R'ed them), then I would consider both torque wrenches to be suspect. That's assuming you're using the correct TQ spec (7-10 lb-ft is the GM service manual spec.) They are somewhat forgiving though, again I've never once used a torque wrench for this and the worst that ever happened was a minor seep that could be sealed up with a slight re-torque after the first heat cycle (and usually not even this.)

murphinator

iTrader: (2)

I have had better luck re using the stock gasket than using any rubber or cork gasket

jeffz

Sounds like you overtorqued. Just make sure the pan is straight, and snug it up by hand with a t-handle or stubby ratchet.

CoreyD

iTrader: (9)

Could it be the rear main seal? Mine use to leak to where it looked like the oil pan gasket was the one leaking.

RPM WS6

iTrader: (3)

I doubt that would be the case in this instance, it's usually pretty easy to tell the difference between trans fluid and engine oil.....unless perhaps the trans is really fried.

jimmyblue

iTrader: (11)

Inspect the pan for signs of overtorque, like the holes
are dimpled upward. Pound them flat if need be. But
if this is all on one trans and the leaks always in the
same place, could be a housing porosity or crack
problem? What's the consistency picture here?

popeye101

I know question is old. But i didn't see any reply as to the gasket itself. The Gasket can be moved during reinstall, i have seen it happen. Have you put a little dab of permatex, Red, gasket sealer a dot every few inches will keep it from slipping. Only use it on the Pan side. Not the top side were it seal's on transmission itself, this way the surface of transmission will remain Clean and smooth. Never scrape transmission area as it can get scratches may cause leaking. If any old gasket material is left on areas it also can cause leaking. Hope this helps other's running into this post. As I did in 2021

TXjeepTJ

iTrader: (8)

Just an update to this thread --- The guy above was right. On the 4L60E (changed the gasket TWICE) and the 4L80E, the leak was in fact actually coming from the main electrical plug on the side. Fluid was seeping in through the pins, would leak down slowly to the pan and look like a pan gasket failure

RPM WS6

iTrader: (3)

Thanks for coming back to this all these years later with an update. Hopefully this will help someone in the future.

BryScan

I have done several of these on my 4L60E and have never used a torque wrench. I snug them up by feel in the pattern recommended. I have always used the rubber gasket but have always also used a small amount of RTV mostly to hold the gasket in place. When Im torquing the bolts I will repeat the process 3 times as I have found that one time is definitely not enough and even after twice I can still feel slight differences in how tight one bolt is compared to another. I have never even had to go back and re-tighten any of them due to the pan having a leak. Maybe give this method a try. The cork gaskets are crap in my opinion, too easy to overtighten and smash them.

99 Black Bird T/A

iTrader: (4)

TXjeepTJ, A++

Thank you for the follow up!
It's always great to know the outcome and issue.