My engine overheats when the air conditioner is running. When the air conditioner is off the thermostat returns to normal... I have replace the coolant, thermostat, radiator cap, radiator heat sensor, all hoses and installed a new radiator. Could my problem be a bad water pump? The timing and head gasket are fine...
Engine Overheating on 1998 BMW 740i
by Pollard in Victorville, CA on July 18, 2010
ANSWER by Chow , July 20, 2010
If the coolant has been bled properly, no leaks present, check viscous fan operation, thermofan operation, thermoswitch operation, remove and visually check waterpump.