Yamaha - Water Seal Cooling System Sealing Component 6E5-44365-00-00. Overview. When you have been around Yamaha outboards long enough, you learn that cooling system seals are the kind of parts you do not ignore. The Yamaha Water Seal 6E5-44365-00-00 helps keep cooling water where it belongs so the system can do its job without leaks or pressure loss. It is a small part, but on older two strokes, offshore motors, and high performance models alike, a worn seal can turn into a bigger problem fast.