Yamaha - Water Tube Cooling System Component 6GH-44361-00-00. Overview. When you're working on Yamaha cooling systems, the water tube is one of those parts you don't think about until something goes wrong. I've seen engines overheat just because of a damaged or misaligned tube during a lower unit install. The Yamaha Water Tube 6GH-44361-00-00 is what carries water from the pump up into the powerhead, so it has to be right. If it's sealed and aligned properly, the whole cooling system does its jo