Yamaha - Water Tube Cooling System 6D8-44361-10-00. Overview. The water tube is one of those parts that just needs to work, no questions asked. It's responsible for carrying cooling water from the pump up into the engine, and if anything's off-alignment, corrosion, or damage-you'll start seeing temperature issues. I've run into overheating problems that came down to nothing more than a compromised tube. Keeping this piece straight and sealed makes all the difference in reliable cooling.. Key Features. Direct Cooling Water Transfer - Delivers steady water flow from the lower unit to the powerhead.. Rigid Tube Design - Maintains proper alignment under vibration and engine movement.. Corrosion-Resistant Construction - Built to handle long-term exposure to harsh marine environments.. OEM Precision Fitment - Matches factory specifications for correct routing and installation.. Engine & Boat Compatibility. Designed for Yamaha outboard engines with standard water pump cooling systems. Commonl