Transmission Leak - At My Wit's End

[Tim Denning]

1986 D150 with A904 Automatic. Trasmission was slipping and leaky so I rebuilt it. After rebuild it worked great but the stamped steel pan was still leaking.

Dropped the pan and replaced with high capacity cast aluminum unit from Summit along with Lube-Locker transmission gasket. Still leaking around pan edge.

Inspection revealed that the lube-locker gasket sealing line was partially exposed on one side of the pan. Notified Summit and they sent another gasket out right away.

In the meantime, I decided to try 'The Right Stuff' gasket maker. Massive leaking all along the pan edge. Drain the fluid and drop the pan again. Sanded the pan lip using a granite slab with 220 grit. Sanding marks showed lots of warping on the pan edges. Sanded until a uniform sanding pattern appeared on the lip.

Noticed that the new gasket looked just like the gasket that was already installed. Checked gasket against original steel pan. Perfect fit. The new cast pan came with a cheap paper gasket so I installed it along with the expensive gasket in case that would help. No extra sealant applied and torqued per spec.

After install and test drive, dry as a bone.

5 days later, truck not moved...still dry as a bone.

2 days later, truck still not moved (but a storm did come thru)...Leaking around the edge of the pan! What the H*LL!

Does anyone know how a transmission pan can leak like that after sitting for many days without any changes?

Note: I'm pretty sure that there must be something up with the new transmission pan but I just wanted to check here in case there is something else I can do (Aluminum pans aren't cheap).

 

[Octane]

Overtorqueing trans pan bolts are a very prevalent cause of leakage/seepage.

 

[Tim Denning]

That's true. I tried to make sure I torqued to my book spec which is 96 inch/lbs. Of course, that assumes my Lowes torque wrench is accurate.

 

[PaPitt]

I worked fro Chrysler ... As a Service Advisor ... The transmission guy ALWAYS CLAMED that the only gasket to use was the Chrysler gasket .. CUSTOMERS would come into with leaking trans. & THE GUYS Would always claim the only fix was to put the Chrysler gasket on the problem.
.... Now I'd came to them with 30 years of owning my own parts store & I'd sold ATP brand trans parts for the last 25 years .. & I don't remember have but a hand ful of leaking problems But a new gasket fixed them up.
..........
..... Now the ATP Gasket had a sealer impregnated into the gasket so you didn't us any extra sealer on it . The trans fluid activated it.
.....

...Now the Chrysler gasket was a thick gasket that was to be reused. This gasket cost about $45.00...
I'm about to change the fluid in my 727 1988 tr. & I'm not going to buy a CHRYSLER GASKET .. If my trans has a reusable gasket on it I look it over & Make my decision as to whether to use it or go with an ATP gasket ..
..........
.... Hope my experience helps you out .

 

[Octane]

Factory used atv only on my '13 Ram.But when I serviced it I used a gasket

 

[PaPitt]

Yes that ATV Chrysler had was a silver gasket sealer & It was good. You can buy it from Dodge.
If you know a dodge tech they always have about 40 small tubes in their tool boxes.
I'd forgot about that stuff . I need to go see Skitter Joe & get my self about 5 tubes of freebie sealer . GOOD STUFF.

 

[Ricks Ram]

That's true. I tried to make sure I torqued to my book spec which is 96 inch/lbs. Of course, that assumes my Lowes torque wrench is accurate.

The factory steel pan has a little bit of flex to it and can actually contour a little better to the mating surface of the transmission. Obviously the aluminum pan will not flex at all so it's less forgiving if your mating surfaces are a little off. Another thing to consider is if the pan is leaking in the same place everytime you re install it there is a possibility that the pan has a casting flaw or hairline crack and fluid is actually seeping out of the pan and not actually between the pan gasket and transmission. If your new and old pan are leaking in the same place you could have a hair line crack in the actual transmission. I have seen this happen a few times. Have you also checked the pan from edge to edge to make sure it's perfectly flat? It may also be helpful to look for reviews on the pan online and see if anyone has run into the same issues you are having.

Sent from my SM-G960U using Tapatalk

 

[PaPitt]

DID YOU EVER GET THIS FIXED .
Find your issue.