[PetChemMan]

There are a lot of variables involved in judging whether your car is running too hot, but the bottom line is whether it boils over during the type of operation you give it. With a 50/50 mix of antifreeze/ water and a 12 to 15 psi radiator cap, you can run up to about 240 F before your coolant boils. In summer driving, if you can get the engine to maintain at least 190 F and no more than 220 F, you're doing fine. The most common causes of overheating are a bad thermostat, ( or one with too high a rating) , a blocked radiator, collapsed radiator hoses, bad viscous fan drive, slipping fan belt, or engine problems such as a blown head gasket or retarded ignition timing. Some aftermarket flex fans are inadequate, and electric fans can be worse yet.