A water pump, aka coolant pump, is a belt-driven device used in motor vehicles to maintain the circulation of the coolant from the radiator to the engine.
The combustion of fuel and air produces mechanical energy (motion), but aside from that, it also expels heat energy. Without a water pump to cool the system, heat can build up inside the engine and cause overheating.
Depending on the car model, the drive belt could be a fan, serpentine or timing. A timing chain can also be used in place of the belt. However, with a timing chain, the water used for cooling can end up mixing with the oil once the pump fails and cause the engine bearings to fail.
The exterior of the water pump of various cars may differ from each other, but the interior parts perform the same function and thus will be similar in construction.
A car water pump keeps the temperature inside the engine at acceptable levels by dissipating heat. It is essentially the heart of the automotive cooling system, because the car water pump function is to continuously circulate the engine coolant from the radiator to the engine and back to the radiator.
Without it, you will not enjoy a comfortable ride.
Car water pumps are shaped like a disc at the center and are made of a steel-and-aluminum material. The inner part of this device is circular and has chambers. In the middle is a spindle with paddle-like protrusions radiating outwards.
Of these protrusions, one is connected to the radiator while another attaches to the engine. Once a car pump malfunctions, both engine and car will overheat, which in turn may lead to many other problems.
The water pump is positioned just behind the fan belt and are usually bolted on the engine mount. In some cars, it is located on the front, while in others, it is on the side.
A hose connects it to the radiator, another set of hoses connects the pump to the engine, while a fan belt connects the pump’s central spindle to the engine output.
The pump is powered by the engine and typically operates through a belt-and-pulley system, but a gearing chain could also be used.
It operates by applying the concept of centrifugal force. When the engine runs, the fan belt turns. The turning fan belt will then cause the axle and the connected vanes to rotate. This rotating motion creates a suction force, which pulls water from the radiator.
The massive power generated by the vanes forces the water against the exterior walls of the pump, pushing it to the engine block and the cylinder head.
From the cylinder head, water then flows back into the radiator. The cycle starts again and repeats this process over and over as long as the engine keeps on running. The thermostat ensures that the amount of water flowing through the system is enough to cool the engine.
The coolant pump can move over 7,000 gallons of coolant in an hour. At peak RPM, the pump can recirculate the coolant over 20 times in a minute. The circulation rate depends on the speed of the engine. If the engine speed is slow, the pump will also work at a lower circulation rate.
When the engine speed increases, it generates more heat. As the new conditions require more cooling, the impeller will operate at higher speeds.
Here are the main car water pump parts:
Housing – It refers to the shell encasing the pump and is typically made from iron or cast aluminum. Nowadays, stamped-steel is also used.
Weep Hole – The weep hole is located in the housing of the pump. It is a small part, but it has an important role. It ensures that the leaking coolant escapes instead of being trapped. If trapped within the pump, the leaking coolant will affect other components. More about weep holes in the section below.
Impeller – Unlike the housing, which is made from metallic elements, the impeller can be made from metal or plastic. It ensures the perfect distribution of the coolant. The rate at which the impeller distributes the coolant is dependent on the engine’s RPM.
Seal – As the name suggests, it ensures that the coolant cannot enter the bearing assembly. Coolant leakage is mostly due to seal failure. These leaks can cause the water pump to fail.
Bearing – The bearing assembly supports the shaft to help it achieve a continuous, controlled, and stable rotation.
Hub or Pulley – The hub or pulley is connected at the top of the shaft. It ensures that the pump has enough power to rotate the impeller and drive the coolant through the engine.