Yamaha - Water Pump Housing Assembly Cooling System Component 6L5-44360-01-00 / 6L5-44360-02-00. Overview. When you're working on the cooling system, the housing is one of those parts that can get overlooked until it's worn or scored. If it's not in good shape, even a new impeller won't perform the way it should. I've run into plenty of cases where weak water flow came down to the housing, not the pump itself. Replacing it keeps everything tight and lets the cooling system do its job without fig