My '94 Protege overheats especially while the engine sits at idle speed. Coolant level is OK. No oil/coolant cross- contamination and no smoking from tailpipe. Both fans operate. Belts not slipping. I did discover that if I increase the engine rpm while the car is not moving it lowers the gauge back to/near normal. My theory is that the water pump is failing to circulate enough coolant to maintain the proper temperature within specs. But, before I change it (which involves removal of the timing belt and my consuming several aspirin), I would appreciate any advice/opinions especially if you have dealt with this problem. Thanks!
Your theory is probably correct. The two most likely causes are restrictions in the radiator due to age and internal deposits, and a water pump with eroded impelllars (a worn uot pump).
The radiator can be checked with a pyrometer that “sees” temperatures. You can “map” the radiator with one, looking for anomolies in teh heat dissipation.
The water pump can be flow tested.
Thanks for your help!
That answer is perfect. Just also run the heater and fan full out on the way to repair shop.