Yamaha - Water Pump Repair Kit Cooling System Service Kit 6A1-W0078-01-00. Overview. If there's one maintenance job you don't skip on an outboard, it's the water pump. When it's fresh, you get strong water flow and steady temps without thinking twice. But once it starts wearing out, overheating can sneak up on you fast. This kit is what you grab when you want to service it properly and know your cooling system is ready for the next long run.. Key Features. Complete Service Kit - Includes essential components needed to restore water pump performance.. Strong Water Flow Output - Helps maintain proper cooling circulation through the engine.. OEM Component Quality - Built to Yamaha specifications for reliable fit and operation.. Preventative Maintenance Ready - Ideal for scheduled service to avoid overheating issues.. Engine & Boat Compatibility. Designed for Yamaha outboard engines using this style of water pump system. Commonly used across a range of Yamaha applications where consistent