Yamaha - Water Tube 1 Cooling System Tube 6CJ-44361-10-00. Overview. On a Yamaha outboard, cooling flow is everything, and this water tube is a key part of that system. It's what carries water from the lower unit up into the powerhead, and if it's not right, the engine will let you know fast. I've seen overheating issues come down to something as simple as a misaligned or worn tube. When it's set up properly, water flows steady and the motor stays cool even on long runs.. Key Features. • Direct Water Transfer Path - Moves cooling water efficiently from the lower unit to the engine.• Precision Fit Design - Ensures proper alignment for consistent and uninterrupted water flow.• Durable Tube Construction - Built to handle pressure, heat, and constant water movement.• Reliable Cooling Support - Helps maintain stable engine temperature during operation.• Corrosion-Resistant Build - Designed to withstand freshwater and saltwater environments.. Engine & Boat Compatibility. Designed for Yamaha