Engine overheating: What is a normal engine and coolant temperature and what causes a car to overheat?
For most of the modern car, the normal operating engine temperature is in the range of 75 to 105 degrees Celsius. When it reaches 80-90 degrees, the thermostat allows the cooling fluid flow through the other cooling circuit. If the temperature continues rising, the radiator fan starts cooling the engine. An engine cooling system is a complex structure with many components which, if malfunctioning, can cause the engine to overheat.