Water pump for window washer unit

A water pump for a window washer unit of a vehicle, the pump having a reversible motor, one inlet port and two outlet ports and being arranged to deliver water selectively to either one of the outlet ports in dependence upon the direction of rotation of the motor, wherein the pump comprises an impeller rotatable in a pump housing and a valve body surrounding the impeller, defining the outer periphery of the pump outlet from the impeller, and movable in dependence upon the direction of rotation of the motor to close the other of the two outlet ports, the valve body being in the form of a drum having a slotted hub which is urged by a clamping ring into frictional engagement with the drive shaft to constitute a slipping clutch, and the outer surface of the drum having at least one radially projecting stop cooperating with abutments in the pump housing to define predetermined end positions for the drum in which a radial opening in the drum is selectively aligned with one or the other of the two outlet ports and the remaining outlet port is closed off by the drum.