IMPULSOR

Function and technical context

The impeller is the heart of the water cooling system in outboard and stationary marine engines: its flexible rubber vanes generate the flow necessary to absorb heat from the engine block and exhaust manifolds, maintaining the working temperature within safe ranges. Housed in the water pump of the transfer case or tail unit, it rotates at high dry speed during the first seconds of each start, causing progressive wear of the vanes with use. When the impeller loses efficiency, coolant flow decreases and the engine can severely overheat, with the consequent risk of damage to head gaskets, pistons and exhaust circuit components.

When to replace this part?

The most common symptoms of a damaged impeller are the absence or reduction of the cooling water jet on the outlet indicator ("tell-tale"), the temperature light coming on or the engine thermal safety limiter tripping. It is recommended to replace the impeller every 200-300 hours of navigation or, at least, every two seasons, regardless of the visual appearance of the paddles, since the rubber loses elasticity over time even if it does not present visible breaks. Changing the impeller preventively during seasonal maintenance is the most economical measure to avoid failure due to overheating at sea.

Compatibility

Equivalent manufacturer part numbers