Th350 strange leak problem

[asfasasu3]

Our truck has, as mentioned, a th350. When it sits for more than 2 to 3 days, it starts leaking fluid. I have changed all the usual seals and it still does it. If we drive it every day, which is kinda hard since we don't have plates on it yet, it doesn't seem to leak at all. I am wondering if there is a check valve inside somewhere that is stuck open and it lets the trans cooler drain back to the pan, and being overfull, lets it leak. Do any of you guys know enough about the internals to know if this could be our weird leak problem? OR does anyone have any other ideas?

[racer1182]

do you have the vent plugged off? seems to me like you have it plugged. there is a little vent tube towards the top of the transmission case. might want to check it out

[manyfire]

I had a similar problem mine was caused by one of the lines going to the cooler the nut was not seated all the way, aggravated the piss out of me, like you said it only leaked when the truck sat for more than a day.

[Scotty_S-15]

What it is, (or so I am told) is that it's the converter slowly leaking down, filling the trans up way beyond what it holds when running. The fluid backs up and comes out the filler tube O-ring, shift lever shaft, you name it. Only seems to happen with trans's with that had work done, (shift kit?) But I don't know 'zactly why.

I've had that problem myself on and off, depending on trans / converter.

Ideally, if the trans seals are in perfect shape, no problem. But in the real world that NEVER seems to be the case.
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