Yamaha - Water Tube Assembly Cooling System Water Transfer 6EE-G4360-10-00. Overview. Water tubes are one of those parts you don't think about until cooling issues start creeping in. I've seen engines run hot just because this tube was bent, clogged, or not sealing right after a lower unit install. It's what carries water up from the pump to the powerhead, so it has to be straight and sealed every time. When it's right, the cooling system just does its job and you don't have to worry about it..