[bigcat_lu]

Since Jan I noticed my 2012 X3 35i may have cooling system issue. The radiator fan comes on and stays on (may be off for 10 seconds then on again) after a short drive (~5 miles). Even in a cold start, after I turn on the windshield defroster for 2 minutes, it will have the same symptom. The car is only 35k miles, just did a coolant flush last Nov in dealer. Coolant level is fine, no leakage observed, engine temperature is normal , no warning sign at all. I checked the OBDII code, no errors. Next week I'm going to bring it to dealer. Does it sound like a thermostat failure? I searched on the web, sounds like changing the thermostat along cost 500. while dealer will recommend changing entire water pump for over 1500. The car is out of warranty. Is it worth to change the entire pump just because of a bad thermostat ( as the car only has 35K miles)?

[02420X3]

It sounds like the thermostat module is failing. The water pumps on 35i's aren't certain to fail, but often do. When my thermostat module failed, it was replaced under a Goodwill warranty. When my water pump later failed, and my dealer recommended replacing both, I pointed out that they had already replaced the t-stat. I paid for the water pump Replacement.

Again, the water pumps on 35i's aren't certain to fail, but often do. Ask your dealer the cost of replacing the thermostat module and the water pump separately, versus changing them at the same time - the labor should be less for replacing both at the same time. Do the math, and figure out what works best for you.