Transmision oil cooler line coupling failure?

g300d · #1 03-09-2013, 03:51 AM

So, I finally found where the oil in my coolant was coming from...the transmision oil cooler.

Got a new trans oil cooler installed and just as I was about to drive off, the lower hose decoupled from the cooler! Lucky the car was stationary, we shut her down right away. Spilled a liter or so of fluid.

Taking a close look at the quick coupling, it seems the hose coupling has a series of spring clips in its mouth that engage a raised flange on the oil cooler tube.

My indy connected them again and put the front of the car on stands to observe. We put the car in reverse and drive multiple times and the hose didnt shift or leak.

My indy recommends replacing the whole hose to be sure.

Are these quick couplings a failure point on these hoses? Do they fail and allow the hose to separate from the cooler?

Or was this improper install by my indy? A part of me thinks he may not have had the coupling fully engaged and so it decoupled with the additional line pressure of shifting into gear.

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upallnight · #2 03-09-2013, 08:59 AM

Sounds like the hose was not connected correctly. If it wasn't a problem before the repair it shouldn't have been a problem after the repair, not unless the hose connector was damaged while trying to remove it for the repair. Did they use a special tool to remove the connector?

g300d · #3 03-09-2013, 04:11 PM

Nope, he did not have the special tool, so a bit of prying was involved.

There were no problems at all before taking it off.

The plastic unlock ring was dislodged from the coupling, so was able to see the actual coupler locking springs engaging the oil cooler flange, it seems secure. Snapped the plastic unlock ring back on the coupling and seems fine.

I am thinking now that when my indy reconnected the line he did not get it all the way in and actually engaged the plastic unlock ring, not the spring clips. So it seemed fine on idle but gave way with more line pressure. That could also explain why the plastic unlock ring was left on the flange when the hose disengaged?

upallnight · #4 03-09-2013, 08:37 PM

I would look for a mechanic that has the correct tools to perform the repairs. Even a DIYer like myself has the tool to remove quick connect hoses.

electricalserv x5 · #5 03-09-2013, 08:50 PM

Hi g3ood,I had the same thing to me with my 4.6is,be careful to replace with bmw transmission fluid.
I am rebuilding my tranny now ,the duma-- IDNY I used shouldn't be allowed to but air in my tires.
How many miles on her?

electricalserv x5 · #6 03-09-2013, 08:56 PM

read your other posting 3good, 35K is low really surprised by the problem.
I am doing a rebuild now for $4200,which is a GREAT price,new TC,valve body, and all the small parts. hey good luck

g300d · #7 03-10-2013, 03:37 AM

Upallnight, yup, lesson learned!

ESx5, sorry to hear that! What happened that led to your rebuild? You had a hose give way too?

papasmurf · #8 03-10-2013, 09:26 AM

A certain Indy made the same mistake on my car as well. The seal was messed up from bouncing around as well. It literally just snaps on.

g300d · #9 03-10-2013, 10:04 AM

Hey papasmurf, yes, the plastic thingy just snapped on. So you had a hose-cooler separation too, was it as simple as putting it back on properly, or did you end up having to replace the hose?

electricalserv x5 · #10 03-10-2013, 10:42 AM

hi 3g00d,I first had the tranny rebuilt [2007]when I lived in SD, I then drove cross country to NY .
I had a lot of problem here with mechanics,and had a InDY here replace the coolant lines to the transmission radiator,the lines blew out , then try to fix it and put non OEM fluid,over time[a year] the year started to fail, I rebuilt to engine sooo I figure I have to fix the transmission too.
I am going a few more minor repairs and the that,s it for me. Really the biggest problem is have mechanics work on the car that are not certified bmw guys, leason learnt.

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