An automobile radiator is a heat exchanger used to cool an internal combustion engine. In a liquid-cooled internal combustion engine, the radiator is connected to channels running through the engine and cylinder head that liquid runs through. The radiator moves the heat from the liquid inside to the air outside.
An automobile radiator is made of a pair of header tanks connected by a core of small passageways that create a high surface area relative to volume. The core is made of stacked layers of sheet metal that is pressed to make channels, then brazed or soldered together. Radiators are also used to cool automatic transmission fluids, air conditioner refrigerant, motor oil or power steering fluid.