Engine cooling

Water pumps – cooling for a long engine life

The water pump is the central component in the coolant circuit. Mechanical water pumps are a well-established solution.

The electrically driven coolant pumps provide demand-based engine cooling, reduce power requirements and cut frictional losses, fuel consumption and pollutant emissions.

Pierburg production sites produce more than seven million mechanical and electrical water pumps for motor vehicles and utility vehicles every year.


Variable mechanical water pumps

With its variable mechanical water pumps, Motorservice offers another innovative state of the art and up to the minute thermal management product in the aftermarket sector. Regulated and demand-based cooling saves fuel and thus reduces CO2 emissions. The options for regulating the volumetric flow include electromagnetic couplings, thermostat modules with thermostat valve, electronically actuated rotary slide valves with worm gear, covering the impeller with an electro hydraulic of pneumatic adjustable ring, and pneumatic bypass flaps inside the pump module. As a result, the pumps are in line with the current trend towards smart accessories in combustion engines.


Mechanical water pumps

The cooling liquid of the water pump absorbs the heat from the engine block and cylinder head and releases it into the ambient air through the cooler. Depending on their design, mechanical water pumps are located either externally on the engine in their own pump housing or are flanged directly on the crankcase and are driven by a V-belt, toothed belt or the engine directly.

Motorservice water pumps have the following quality features: 

  • High-quality sliding ring sealing cartridge
  • Maintenance-free, long-life rolling bearings
  • Flow-optimised impellers made from plastic, steel, aluminium or brass
  • Gaskets and O-rings are included in the scope of supply

Electrical water pumps

Electrical water pumps make a significant contribution to emission control on modern engine designs. 

A delivery rate that is not dependent on the engine speed enables demand-based cooling. This reduces the power requirements whilst also cutting down on frictional loss, fuel consumption and pollutant emissions. 

Pierburg has made this technology ready for series production and is the world’s first series-production supplier of electrical water pumps.


Water circulating pumps

Water circulating pumps are used where cooling or heating functions need to be performed independently of the coolant circuit. In independent heating systems, water circulating pumps are used, for example, to rapidly heat the passenger compartment. 

Ever since they were launched on the market in 1996, more than 50 million water circulating pumps have been produced in Pierburg’s plants.


Further information

High temperatures occur during combustion in the cylinders of an engine. Because these temperatures would damage the
engine, cooling is required. The coolant absorbs the heat from the engine block and cylinder head and releases it into the ambient air through the radiator.

A pump is required for transporting the cooling liquid. This water pump – also known as "coolant pump" – circulates the cooling liquid around a closed circuit. Mechanical water pumps are located either externally in their own pump housing or are flanged directly on the crankcase depending on the design. They are usually driven directly by the engine.

A mixture of water, glycol and different additives is used as cooling liquid. 

The thermostat controls the coolant circuit depending on the temperature of the cooling liquid. When the engine is cold, the thermostat remains closed so that the operating temperature is reached as quickly as possible in a small coolant circuit. Only when a specific temperature is reached does the thermostat connect the large coolant circuit via the radiator.

1 Radiator grille
2 Cooler
3 Water pump
4 Thermostat
5 Temperature feeler
6 Cooling jacket
7 Heater control valve
8 Heat exchanger
9 Water jacket
10 Radiator fan
11 Hose
  • Water pumps are typical wear parts, which must sometimes be replaced several times during the service life of an engine.
  • In the event of engine reconditioning, the water pump should always be replaced to safeguard operational safety.
  • With water pump malfunction the engine overheats, which can result in serious engine damage.
  • Water pumps are attached to the outside of the engine block and can be replaced without having to open the engine.
1 Pulley
2 Leakage bore
3 Scraper ring seal
4 Impeller
5 Pump housing
6 Bearing
7 Bearing shaft
  • Water pumps may be of open or closed design. In the case of open pumps, the engine possesses a flangemounting face to which the pump is fas tened and sealed by means of a sealing ring or a flat gasket. The mating piece of the pump housing is part of the engine. Closed pumps in contrast constitute a complete as sembly.
  • Various types of closed and open pump impellers are used in the mechanical water pumps. The latest calculation methods and flow simulation tools are used to optimise the pump impellers in terms of the hydraulic requirements, the pump efficiency and the geometry, taking into account the manufacturing process.
  • The housing is produced from aluminium or grey cast iron. Various attachments are fitted to the pump housing, such as brackets for hoses, thermostats, plugs, etc.
  • The sliding ring seal is responsible for ensuring tightness between the housing and the bearing shaft. The quality of the sliding ring seal has a significant influence on the durability of the water pump.
  • The leakage hole is used for discharging small quantities of cooling liquid that enters through the scraper ring seal for lubrication and sealing.
  • The water pumps are driven via V-belts, poly-rib V-belts or gears depending on the installation location on the engine. This is achieved either via the toothed belt of the camshaft control system, or via the V-belt or ribbed V-belt of the crankshaft.
  • Mechanical water pumps for utility vehicles are driven by the crankshaft via V-belts, poly-rib V-belt or gears.
  • If the pulley is not already part of the pump, it must be screwed to the flange of the drive shaft.