This particular Sykes water pump is a centrifugal pump, which cannot shift air. In order to get the pump working, it must first be primed (the air must be evacuated from the centrifugal pump. This is done by means of the priming pump, which, in this case, is an eccentric vane pump. This priming pump is pulley driven, and the pulley has a taper lock. This video demonstrates the removal and refitting procedure for the pulley.