Yamaha - Water Pump Repair Kit Cooling System Service Kit 6J8-W0078-A2-00. Overview. The Yamaha Water Pump Repair Kit 6J8-W0078-A2-00 is one of those kits you grab when you want to refresh the entire cooling system instead of just swapping one part. On 2-stroke motors, once the pump starts wearing out, you'll usually notice weaker water flow or temps creeping up. This kit gives you the main components to bring the pump back to full performance in one go. If you're doing maintenance or fixing cooling issues, this is a smart, complete solution.. Key Features. • Complete Pump Service Kit - Includes key components needed to rebuild and restore water pump performance.. • OEM Fit Precision - Built to Yamaha specifications for proper alignment and reliable operation.. • Restores Cooling Performance - Helps bring back strong water flow and proper engine temperature control.. • Durable Marine Components - Designed to handle heat, friction, and long-term marine use.. Engine & Boat Compatibility.