IMPULSOR YAMAHA 9.9/15 HP

Function and technical context

The impeller is the central component of the water cooling system in Yamaha outboard engines, responsible for pumping water from the intake located under the hull to the internal cooling circuit of the engine block. In the 9.9 and 15 hp models, this component works in a continuous regime of demand, driving the flow of water through ducts and galleries to maintain operating temperatures within safe operating margins. Its correct performance is critical: when the impeller wears out or reduces its volumetric efficiency, water circulation decreases significantly, causing progressive overheating of the engine, possible internal cavitation in the cooling galleries and irreversible damage to the cylinders and cylinder head.

When to replace this part?

Impellers require visual inspection every 100-150 hours of operation or at least once at the beginning of each boating season. Typical symptoms of wear include weak water flow in the discharge pipe, frequent overheating of the engine even in cold water, abnormal noises in the water inlet area and progressive loss of revolutions. Preventative replacement of the impeller before it completely fails is an investment that avoids costly boating repairs and significantly extends the life of the engine and its internal components.

Equivalent manufacturer part numbers