1988 GMC Sierra k1500 SLX Transmission Return Line Leak

Asked by Guru1GT6W Jan 30, 2020 at 11:11 PM about the 1988 GMC Sierra 1500 K1500 Standard Cab LB 4WD

Question type: Maintenance & Repair

I got this truck that's been leaking
transmission fluid from the lowest
transmission line on the radiator. It has a
brass fitting, a brass transfer piece, and
another brass fitting connecting the line.
After the third fitting, it leaks where the line
connects after I start it up for half a minute. I
tried sealing it in gasket, soldering it, then
putting high temperature resistant JB Weld
around that, but it still leaks through. Kind of
looks like a wounded Freddy Krueger.
It's also got a leak under the truck from the
transmission. As best I could tell, it was
from either the middle part that looks like
two parts connect and bolt together, or from
the bolts themselves. There was one bolt on
the top of the transmission that wouldn't go
all the way in, like the threads on one side
were half way up the bolt hole the other. I
tried putting gasket around that too, and that
didn't much help.
How should I approach this?

F_O_R answered 4 years ago

This sounds like these are compression fittings. I would probably replace them all. You may need to shorten the fluid line a bit so that there is undamaged tubing to attach to.

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103,105

KenF answered 4 years ago

Yeah I'd replace them too, sometimes just not worth the hassle dealing with old fittings. They sell fitted cooling lines most any parts store.

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