Coolant dripping from the transmission oil cooler

[armiller1]

After I got the power steering pump swapped, I realized I was leaking coolant. It’s dripping from the trans oil cooler. I can’t see where it’s coming from. As far as I can tell, it’s not the alternator. Anyone have this happen? I’m not seeing much when I do a search.


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[armiller1]

Maybe I should be calling this the heat exchanger?


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[RSharma]

If you are sure that the alternator is not dripping coolant down onto it, then check the black plastic part (called a "Voltage Regulator" by BMW) that is mounted on top of the metal part (heat exchanger). There are three coolant hoses going to it. Two are the normal BMW clip type hoses going into the front and back of the voltage regulator. You can check those for leaks.

On the voltage regulator on the side towards the engine, there should be the third hard cooling line that seals using an o-ring. I believe the voltage regulator also has two o-rings on the bottom to connect it to the heat exchanger. Any of these o-rings can begin to leak because of age or because they were roughed up while doing another repair. I have also seen the actual voltage regulator itself develop a hairline crack on the plastic before.

[nmlss2006]

Probably - it's the engine oil heat exchanger, not the trans oil cooler. Edit: no it isn't. Ignore me. But rsharma is still right.

And, Rsharma is right.

[Sundaycruzer]

I have 2-3 of them if you need one


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[armiller1]

I didn’t realize that the voltage regulator was a separate part. Funny thing is, now the leak is minimal, if there’s any leak at all. The car was supposed to be dealer maintained, but the coolant system looked to be overfilled. The there are signs of leakage all over the place, but nothing is currently leaking. The system is still full as well. The top of the heat exchanger is full of crud now so I will have to clean it off somehow.

Thanks guys! I’ll let you know if I need any more help or parts.


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[nmlss2006]

If it's full of crud... simple green. Works wonders in engine bays. Apply, let it rest a bit DO NOT let it dry, remove with microfiber towel, repeat.

In difficult crevices, apply, let it rest a bit, apply again, THEN use not-overly-stiff brush to agitate, then wipe off with microfiber.