Water PumpThe heart of the cooling system is the water pump. Its job is to move the coolant through the cooling system. Typically the water pump is driven by the crankshaft through pulleys and a drive V-belt (Figure 12–37). Some pumps may be driven off the camshaft. No matter how they are driven, they all basically work the same way. The pumps are centrifugal-type pumps (Figure 12–38) with a rotating paddle-wheel-type impeller to move the coolant. The shaft is mounted in the water pump housing and rotates on bearings. At the drive end, the exposed end, a pulley is mounted to accept the belt. The pulley is driven by the crankshaft. The pump housing usually includes the mounting point for the lower radiator hose.