Strange Over Heating Issue
Hey all new to this forum. I'm driving 2002 BMW 325xi. I recently had my expansion tank blow had that replaced. About 2 weeks after car overheated so figured air must be in system. Bled system 2 times with Mechanic thought it was fine then overheated again. Its only overheating when at idle after driving in the city for a while. I can drive in on the highway for 45 mins or longer doing over 80mph and temp gauge stays in the middle. No loss of power, no leaks, headgasket is fine, fan moves when car is hot tension in the morning when cold and sometime after gets to operating temp. Haven't replaced water pump or thermostat yet, but know i need to just need to stop it from overheating!!!!! I don't let it get to the redzone cause the overheat is gradual so turn the heat on and goes back in the middle. Any suggestions on problem will be greatly appreciated. I'm very mechanically inclinded and step dad is US Marine Mechanic and even he's stumped we think it may be the Fan clutch but not sure PLEASE HELP!!!!