Is there a trans thermostat? I have coolant leaking from up above the trans heat exchanger. All the hoses near the multi-connector above the trans cooler appear to have coolant on them. And then I noticed coolant coming from the radiator core face too. If there is indeed a thermostat, has anyone replaced this before?

Trans thermostat
 

On the 4.4 there is a trans themostat that goes to the trans cooler.

Part 15.

RealOEM.com * BMW E53 X5 4.4i RADIATOR/EXPANSION TANK/FRAME

Mine was weeping badly after I replaced my radiator. Its probably an O ring inside it, but I replaced the whole thing.

Does $74-80 sound right for that thermostat? Do I need to get new o-rings and those 'x-ring' connectors for the trans cooler?

Auto Parts at AutohausAZ - OEM Auto Parts - Discount Replacement Parts, Resources and Car Care Tips

has them for 67

I did not replace any o rings when I replaced the thermostat, I can't remember if there are any to replace.

Pic of Thermo with bad O ring
 

I did find the leaking O ring on the old thermo I removed.

http://www.xoutpost.com/members/luke...89-photo-5.jpg


Careful removing the metal clip, There is a Spring that will eject the top across the room. (Not that it happened to me) :rolleyes: