The coolant temperature sensors have nothing to do with overheating while the car is moving and you have plenty of natural air flow. They simply report the temperature to the Engine Computer or dash gauge. From your description, the best suspect is a leaking cylinder head gasket. Your mechanic can perform a fast chemical test at the radiator to identify that. It involves drawing air from the radiator, while the engine is running, through a glass cylinder with two chambers partially-filled with a special dark blue liquid. If combustion gases are present, the liquid will turn bright yellow.
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Saturday, August 27th, 2016 AT 12:58 PM