Radiators are heat exchangers used for cooling internal combustion engines. Internal combustion engines are often cooled by circulating a liquid called engine coolant through the engine block, where it is heated, then through a radiator where it loses heat to the atmosphere, and then returned to the engine. Engine coolant is usually water-based but may also be oil. It is common to employ a water pump to force the engine coolant to circulate, and for an axial fan to force air through the radiator. The radiator works by passing your coolant through thin metal fins, which allow the heat to flow to the air outside your car much more easily. A radiator fan blows air across the radiator in order to carry the hot air out of your car. A malfunctioning radiator may cause significant engine damage caused by overheating it is not advisable to run the car with a damaged radiator.