First you need to make sure it is actually not heating up. Do this by checking to see if the radiator hoses are getting warm after running for 10-15 min. Be careful they could be HOT. If the hoses are hot then the heater core is plugged and will need to be replaced. If hoses do in fact not get hot then the thermostat is most likely stuck open. removing it will tell the tale.
Heat, lack of lubrication, or coolant in the cylinders or oil pan.
The combustion process cause the engine to heat up.
what causes rear wheel rotors to heat up
FRICTION
No heat coming from the heater and the car overheating is usually the thermostat stuck closed. The thermostat is supposed to open up at a certain temperature allowing the engine to warm up quickly.
the sun
The heat from the friction of the tire rolling at a high speed on the street causes the rubber to slowly burn up.
If you run your car with the emergency brake on it will heat the car up.
The Greenhouse effect...
It generates heat (from kinetic energy of the car).
Car heaters need a few moments to warm up.
#1 cause Heat, #2 Heat, #3 Heat, #4 Sulfation usually caused by electrolyte loss because of heat.