Yamaha - Water Tube Cooling System Component 6K5-44361-10-00. Overview. The Yamaha Water Tube 6K5-44361-10-00 is one of those parts you don't see working, but you'll definitely notice when it isn't. It carries cooling water up from the lower unit to the powerhead, keeping engine temps where they should be. When these tubes corrode, clog, or get misaligned, overheating isn't far behind. It's a simple piece, but it plays a big role in keeping your motor alive on long runs.. Key Features. • Direct Cooling Water Delivery - Moves water efficiently from the lower unit to the engine.. • OEM Fit and Routing - Designed to align correctly within Yamaha cooling passages.. • Corrosion-Resistant Build - Holds up against constant water exposure and marine conditions.. • Maintains Engine Temperature - Supports consistent cooling to prevent overheating.. Compatibility. Compatible with select Yamaha outboard engines using this water tube configuration.Commonly found in mid-range Yamaha outboards with s