Water and Oil Pumps

The water pump is usually of the centrifugal type: an impeller with radial vanes housed in a special compartment. The water pump activates the coolant liquid circulation in the cooling circuit and it is often driven by a V-belt or by the same toothed belt which drives the camshaft. The oil pump instead picks up lubricant from the sump and provides to send it under pressure to the engine lubrication circuit. It can be a gear or lobe type and is provided with a pressure relief valve: this is very important because it opens moving back, or at least upstream of the pump, a part of the oil when the pressure in the circuit exceeds a predetermined value. In engines with dry sump lubrication, the oil pumps are at least two, one for delivery and one for recovery.