Yamaha - Tube,water - 6K5-44361-10-00Yamaha Water Tube Cooling System Component 6K5 44361 10 00 Overview The Yamaha Water Tube 6K5 44361 10 00 is one of those parts you dont see working, but youll definitely notice when it isnt. 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 isnt far behind. Its a simple piece, but it plays a big role in keeping your motor alive on