Yamaha - Water Pump Body Assembly Cooling System Component YF1-43847-34-00. Overview. When you're rebuilding a Yamaha water pump, the body is what everything depends on lining up right. I've seen pumps struggle just because the housing was worn or scored, even with a new impeller installed. The Yamaha Water Pump Body Assembly YF1-43847-34-00 gives you that solid foundation so water moves clean and efficiently through the system. It's one of those parts that keeps the whole cooling setup working