YAMAHA WATER PUMP KIT 6H4-W0078-00

Function and technical context

This water pump kit constitutes the central element of the cooling system in medium power Yamaha outboard engines. The pump drives the flow of seawater through the internal galleries of the engine block, absorbing the heat generated by combustion and dissipating it to the outside through the cooling discharge. The correct operation of this unit is essential to maintain the optimal engine temperature and prevent overheating, a phenomenon that can cause severe damage to cylinders, head gaskets and internal components of the block. Any degradation in the impeller or loss of tightness in the seals directly compromises the effectiveness of the cooling system, reducing the useful life of the impeller.

When to replace this part?

Typical symptoms of wear include abnormal temperature rise on the cabin gauge, visible reduction in water flow at the cooling outlet, and water dripping or leaking around the pump housing. It is recommended to inspect the condition of the impeller and seals during each seasonal maintenance, especially after prolonged operations in waters with a high concentration of sediment, algae or contaminants that accelerate wear. Preventive replacement of the kit prevents emergency engine repairs and ensures reliable performance throughout the sailing campaign.

Compatible Yamaha engines

Equivalent manufacturer part numbers