IMPULSOR 9.9/15 Y 9.8/14 4 T

Function and technical context

The rubber impeller is the heart of the water cooling system in 4-stroke outboard engines, responsible for continuously pumping sea or river water through the engine cooling circuit. Housed in the lower transmission case water pump, its flexible vanes generate the flow necessary to maintain engine block temperature within safe operating ranges. A bad impeller causes insufficient cooling which can lead to severe overheating, cylinder head damage, warping of gaskets and, in extreme cases, complete engine disablement offshore.

When to replace this part?

The most common symptoms of a worn impeller are the decrease or absence of the cooling water jet ("tell-tale" or snitch), the overtemperature warning light going off and an abnormal increase in engine temperature even at low revolutions. It is recommended to replace the impeller every 200-300 hours of navigation or at least every two seasons, regardless of its apparent condition, since the rubber vanes lose flexibility and efficiency with time and heat. Changing it preventively during seasonal maintenance is the most economical measure to avoid a serious breakdown at sea.

Compatible engines

Equivalent manufacturer part numbers