A cars engine has a variety of moving parts, which in turn creates heat. If the engine block gets too hot you run the risk of seizing or severely damaging the engine. In order to prevent this, radiators are fitted to help reduce this risk. The failure of the car radiator is one of the most common causes of a vehicle breaking down. This is why its important to maintain a full coolant level, especially during hot weather or long drives.
If anything goes wrong with the radiator itself, such as a leak or broken hose, the temperature of the engine can reach a dangerous level within minutes. The engine must be allowed to cool down naturally before the vehicle can be driven safely.