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4t80e leak questions

Posted: Mon Sep 10, 2018 8:50 pm
by skregal
These *dang* fluid leaks just never end.

So first the ATF cooler line leaked badly at the lower back of the tranny.
Replaced the snap in fitting and it still leaked. JB weld lasted 3 months.
Replaced entire line and finally got that one stopped. That sucked BTW.

Following week the driver's output shaft seal started dumping ATF.
Research shows that these trannys, when old, start wearing the bearings
on the internal shaft causing it to wobble and blow the seal. With the transaxle out, i had
no play or wobble in the internal shaft. Whew! New seal banged into place and
that leak stopped.

One week later I am seeing smoke and smelling burning ATF. Now I have a
leak on top somewhere and it's running down the exhaust crossover pipe and
burning off. I can see a puddle just below the shift lever and the vent tube.
I thought it was the vent, but after removing and cleaning and reattaching with
a clamp, it is not the vent tube. It's not the fill cap either. It's more towards
the firewall.

I can't see anything else where it could be leaking. Does the shift lever have
a seal that is prone to leak? That would seem weird as it faces upward.
I'm reaching here for suggestions I know, but my garage floor has been
covered in ATF for months, and I don't want the car to catch fire. (or do I?) :-k

Re: 4t80e leak questions

Posted: Thu Sep 13, 2018 8:52 pm
by skregal
After much testing and checking and cleaning, I'm reconsidering my first diagnosis and think maybe it might be the vent tube.
With the large leaks over the last few months, I have had to add ATF every other day, and
checking for a perfectly accurate level was non-existent.

Finally with a good level check it appears the transmission is just slightly overfilled. I zip tied rags over the vent tube
and sure enough they got red next trip. It's funny how the tube didn't show signs of leaking
previously as it always appeared dry.

Another problem that may be contributing, is the transmission is shifting really late.
Sometimes holding first gear waaaaaaaaay too long.
I don't know if that could be forcing fluid up the vent. Hell, I don't even know how
these things work with their stupid solenoids and pumps and flexplates, blah, blah.