Yamaha - Water Pump Housing Cooling System 6E0-44311-00-00. Overview. If you've spent any time maintaining small Yamaha outboards, you know the water pump housing takes a beating over time. This housing sits right where all the cooling water starts its journey, so wear from sand, silt, and heat cycles is just part of its life. When it starts to score or warp, you'll notice it in your engine temps pretty quickly. Swapping it out restores proper water flow and keeps your motor running the way it s