Overheating is caused by anything that leads to a loss of coolant, prevents the cooling system from getting rid of heat, or causes excess heat in the engine itself.  There are several components or conditions that can cause overheating;  water pump, radiator, heater core, hoses, freeze plugs, head gasket, radiator cap, deposits and build up, thermostat, cooling fan, fan clutch, shroud, fan belt, ignition timing, or exhaust system.  It’s important to discover the cause of overheating before you become stranded and do major damage to your engine.