Yamaha - Water Pump Housing - 6BX-44311-00-00 - F4 (Sept 2009 & newer)Yamaha Water Pump Housing Cooling System Component F4 6BX 44311 00 00 Overview On small four stroke Yamahas like the F4, the cooling system doesnt have much room for error. This water pump housing is what keeps the impeller properly contained and directs water flow through the engine. When it starts to wear or get scored, cooling efficiency drops off fast, and thats when problems start. Swapping it out during service keeps things running cool and