Yamaha - Water Tube Cooling System Transfer 6H3-44361-10-00. Overview. The water tube is one of those parts you don't think about until cooling issues show up. I've seen engines overheat just because this tube wasn't sealing right or got bent during a lower unit install. It's what carries water from the pump up into the powerhead, so it has to line up perfectly every time. When it's right, you get steady cooling flow and no surprises on the water.. Key Features. Direct Water Transfer Path - Carries cooling water from the lower unit to the engine for proper temperature control.. Precision Fit Alignment - Designed to match Yamaha specs for correct positioning during installation.. Corrosion-Resistant Material - Built to withstand constant water exposure in marine environments.. Maintains Cooling Efficiency - Supports steady water flow to prevent overheating issues.. Service-Ready Component - Ideal to inspect or replace during water pump or lower unit service.. Engine & Boat Compatibility