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Leaky trans cooler lines

Hi All,

I ran across a discussion, that described a repair of leaky trans

cooler lines and am wondering if

anyone here has done this.

The repair is for the leaky compression fitting at the metal

rubber hose union. Instead of

buying a new metal/rubber hose

cooler line, the remedy is to

carefully cut the metal compression fitting and peel it off. Next pull off old rubber hose

and replace with new 400psi cooler line, that is cut longer

to fit over the ribbed metal edge

and then apply hose clamps on both sides of the metal rib.

The discussion stated that oil pressure is approx 40 psi for an

auto trans, and therefore this rememdy should work reliably.

Curious if anyone has done this,

as both trans cooler lines are leaking on my 2000 impala.



I have not done this, but the keys are to specifically use transmission cooler line - nothing else will substitute. The other key is that the metal ends must have something that works like barbs - smooth metal line won’t do it.

Your line pressures will get much higher than 40psi but just use the transmission line.

Did you actually price out whole new lines? They’re not that expensive and not too hard to replace.

I have had no problem replacing the rubber lines using hose clamps even on smooth metal pipe. If the pipe end is coated with gasket shellac and the connection is fixed so that the connection is not pulled apart they seem to hold with no problem. And although I have never tested the pressure on the cooling line it doesn’t appear to be very high. Possibly less than 10psi. But that’s just a guess from observing leaks.

I have replaced leaky transmission line with neoprene fuel line and hose clamps and the only problem I have had is with continued rusting with the remaining metal line.

I did this years ago on a 1986 Buick. I cut the steel line at the rubber junction with a hacksaw and used a flaring tool to flare the bare metal end just a little, not a full flare, to give a ridge. I replaced the leaking rubber portion with transmission cooler line sized to fit the steel lines, cut to a little extra length beyond the original rubber length, and used standard hose clamps to fasten the rubber to the steel. Worked like a charm, and even had a couple of transmission experts commend me on the job.

Those lines will see pressures in the hundreds of psi. Yes, people do clamp rubber lines onto the smooth ends of rubber lines. Sometimes people get away with it. Very frequently they do not. It is a terrible idea unless you never go too far from home and have a good friend with a tow truck.

Thanks for the replies.
I did the repair, using a dremel tool cut disc to make 2 shallow cuts thru the crimp,then used a pair of needle nose pliers to split the crimp and remove it, pulled the hose off
and left the metal tube intact [there were barbed edges, plus 2 rings further in].
I purchased some 3/8 trans hose and cut it 2 in longer than old hose. The hose fit very
snug over the tub, I used a heat gun to heat the end abit so I could push/twist the hose
about an inch past the 2 rings, it felt very tight when done. I installed 2 hoses clamps
[one on either side of rings] and so far no leaks after several test drives.

My main reason for doing the repair vs replacement was those aluminum crimps are prone to
failing after a few thousand miles, plus it allowed me to leave the lines from the radiator
in place, only had to remove the lines at the trans housing, much easier to reach.


The follow up is appreciated. That solution sounds like it should work just fine.