PUMP IMPELLERS
Use Neoprene Impellers for engine cooling, and for fresh or salt water transfer duties. Neoprene is the most commonly used material and is suitable for use where only small amounts of oil or diesel fuel are present.
Use Nitrile Impellers for bilge pumping, and for transfer duties where the water is heavily contaminated by oil or diesel.
Replace all impellers annually, or sooner if engine has high use. A correctly installed impeller may last for several years, but it is easier to replace an impeller than an entire pump.
Always carry spare impellers on board in case of emergency. The impeller is one of the most vital components of the engine cooling system and should always be treated as such.
Always grease new impellers. Firstly, it makes it easier to install the impeller into the pump bore, and secondly it gives added protection to the impeller during initial prime.