21st Century Overview - Cooling

Cooling with water keeps the engine parts at normal operating temperatures, which prevents wear and damage.   (Small engines may be air-cooled.)   The water pump forces the coolant, which is water and antifreeze, through hoses to engine spaces ("jackets") around the cylinders, in the cylinder head, and intake manifold, where it collects heat and passes it through the radiator, which cools the water by the air flowing through it.   A fan draws air against the engine for additional cooling.   A thermostat controls coolant flow and thereby engine temperature.