Yamaha - Water Tube Cooling System Delivery 6E5-44361-00-00. Overview. The water tube is one of those parts you don't see unless you've had a lower unit apart, but it's critical to keeping your engine cool. It carries water from the pump up into the powerhead, and if it's not sealed or aligned right, you'll notice overheating pretty quickly. Over time, these tubes can corrode, clog, or get damaged during service. Having a solid, properly fitted water tube keeps your cooling system flowing like it should when you're out running hard.. Key Features. Direct Water Flow Channel - Transfers cooling water efficiently from the pump to the engine block.. Corrosion-Resistant Build - Designed to withstand constant exposure to water and marine conditions.. Precision Alignment Design - Ensures proper connection between lower unit and powerhead components.. OEM Fit Replacement - Matches original Yamaha specifications for dependable installation.. Engine & Boat Compatibility. Compatible with a wide r