Yamaha - Water Pump Repair Kit Cooling System 6E0-W0078-A4-00. Overview. When you're servicing a Yamaha water pump, it's usually not just the impeller that needs attention. I've opened up plenty of lower units where the whole pump was worn, not just one piece. A full repair kit like this lets you go through everything at once and know it's done right. It saves time, prevents repeat issues, and keeps your cooling system strong every time you hit the water.. Key Features. Complete Pump Rebuild Kit - Includes essential components needed for a full water pump service.. Restores Cooling Efficiency - Helps bring water flow and pressure back to proper levels.. Matched Internal Components - Designed to work together for consistent fit and reliable operation.. Durable Marine Materials - Built to handle heat, friction, and debris in real-world conditions.. Engine & Boat Compatibility. Designed for Yamaha 2-stroke outboard engines using standard water pump systems. Commonly used on smaller horsep