A car's radiator may need to be replaced if it experiences consistent leaks, if there is extensive rusting on the interior and core, or if it cannot process coolant properly. Each scenario can be caused by a lack of consistent maintenance, a faulty part or damage from an accident.
The radiator plays a vital role in the safe and continuous operation of a car because it is responsible for regulating the engine's internal temperature. As the engine burns gasoline to power the internal mechanisms, large amounts of heat are produced as a by-product. If the heat builds up without ever cooling down, it can cause other parts of the engine to wear out or break, as they are not designed to withstand long exposure to high temperatures. The radiator uses special coolant, though many models can use simple water as well, to draw out the heat from the engine and expel it.
Depending on the type and severity of the radiator issues, it may be possible to perform a repair instead of replacing the entire component. For example, some leakage issues are the result of coolant build-up and not a rupture in the internal system. Flushing the radiator can remove the blockage and return it to a normal functioning level.