difficult find
 

I have a 2000 x5 with a 4.4 I have recently replaced the expansion tank, high pressure steering hose, pcv valve, intake gaskets, throttle body gaskets, oil return lines, valve cover gaskets,upper and lower control arms. I did all this work myself but I can not find this leak! I assumed it was a coolant leak because I have had to top off every 2 weeks for the past month, I checked the vally pan and nothing same with all the coolant lines nothing leaking, no coolant in the oil so head gasket is fine. The leak is on the right side of the vehical, it is dripping down on to the thrust arm and it is blue. any ideas would be helpful

radiator?? you need to see where the leak is running from. There should be a trail of dried antifreeze somewhere...that's the problem with coolant leaks...they can run wherever they want.

Could be the sensor for the wiper fluid - either that or if you have headlight washers there could be a leak

HEADLIGHT WASHER hose sounds good if the fluid is blue

The coolant is blue and oily feeling, the washer fluid can be blue and is alcohol based.

A quick pic of the area will help us figure out the possibilities of the area. There are numerous connections that can leak between the aux waterpump, heater valves, coolant temp sensor, etc.

Well after the fluid hits the ground and evaporates it does not leave a ground stain like coolant normally would. so this sounds like a washer fluid like. But I still don't know why my coolant level goes down when i dont have a leak could it be that I did not put enough coolant in when I replaced the resevoir? any suggestions?

If you bled the system after all the coolant system work, have you tried pressure testing the system and the cap.

do a pressure test to see if the leak is really in your cooling system. if it's really coolant, the leak you indicated might be from o-rings on the transmission fluid heat exchanger to radiator connections.(2 o-rings there. inlet and outlet)

I just did this same repair myself, but it was my understanding that the OP had a 4.4. Wasn't the transmission cooler just on 4.6/4.8 models?

all transmissions need cooler. :) it's in the same location on 4.4 and 4.6(M62 engine). It's on the driver side on 4.8(N62) which is similar to 3.0 design.

JTis, how did you find the leak from there. It's pretty deceiving location as most people would think radiator is punctured or it leaks from the thermostat right above the heat exchanger.