Wait until it does. If the coolant is low, start the engine, and slowly add the water or coolant necessary to fill it up. By running the engine, the coolant keeps moving and reduces the chances of this type of damage occurring. Water Pump Water pumps come in many designs, but most include a rotating impeller, which forces the coolant through the engine block. In most rear wheel drive cars, the fan is installed on the end of the water pump shaft.
Many water pumps have a spring-loaded seal to avoid leakage of water around the pump shaft.
Modern pumps are fitted with pre-packed ball bearings, which are sealed at each end to eliminate the need for lubrication. Impeller type water pumps must turn rapidly to be efficient, and worn or loose drive belts can permit slippage which is not easily detected. Tank Several cooling systems make use of a clear plastic container, which is connected to the overflow tube from the radiator. This container provides extra storage space for the coolant when it expands and is called the expansion, or overflow tank. It is also known as the coolant reservoir, or overflow canister.