Timing belt and water pump for your car

Heavy duty – easy replacement: the water pump

The water pump is part of the cooling circuit, enabling permanent coolant circulation. By doing so, it is subject to high stress. Depending on car, this component can perform additional tasks. The water pump is very accessible in most engines and easy to replace.

Construction and location of the water pump

The water pump is a massive cast aluminium component with a shaft running through. It is screwed to the engine block. On one end the shaft is driven. Its other end has an impeller. Several constructions are possible with the aluminium turbine being the most common option. The water pump can be driven by a chain, a gearwheel or a timing belt. If the water pump is driven by a timing belt, it is often used for tensioning it as well. This construction is often found in the Volkswagen cars.

Defects of the water pump

The water pump is permanently operational. Deposits in the coolant, rust and ageing particularly affect the shaft. A malfunctioning coolant pump initially squeaks softly and gradually louder. If you ignore the squeak for too long, the pump may ultimately jam or disintegrate. In both cases the engine is under great risk. The water pump can start leaking as well, which is noticed by continuous loss of water.

Repairing the water pump

A water pump's construction does not allow for its disassembly or repair. This would be too dangerous as a defective or ill-repaired water pump would quickly lead to engine damage. It is easy to find and to replace: it is fixed to the engine block with several screws and can be easily removed and replaced by a new coolant pump. When the water pump is at the same time the belt tensioner, it is generally part of a full repair kit. For all other versions of this wear part, fixed maintenance intervals apply. It is not recommended to wait until it starts squeaking. At that moment the service interval has been surpassed and the pump will sooner or later start to leak. The water pump has a life span of 60.000 – 100.000 kilometres.

Stay away from too cheap coolant pumps!

Water pumps are subject to heavy stress and only branded quality can be considered for these parts. Cheap water pumps have a shorter life span and particularly problematic are spare parts of unknown origin if the water pump doesn't match the timing belt. The timing belt drives the water pump, and its tension is maintained by it as well. If the water pump jams, even if only for a short while, the timing belt could skip which would mean serious danger for the engine as pistons and valves no longer run synchronously. Even branded water pumps are so cheap that experiments with cheap spare parts are not worthwhile.

Costs for a new water pump

Costs do not so much depend on the brand, but rather on the car in which it is installed. The differences are considerable: prices for a Bosch water pump for VW Polo start at 60 euro (c. £54). High-performance water pumps from Pierburg for high-HP BMW cars cost four times as much. Nevertheless, the principle of branded quality should be observed. It is advised to replace the water pump according to service schedule – by doing so you guard yourself against the highest of all expenses: engine repair or the purchase of a new engine.