The heart of the Cooling System is the flexible Impeller located in the sea water pump. A spare should be kept on board at all times for quick service in the event of overheating. Badly bent blades and/or missing blades indicates time for replacement. *Tech Tip* Most people remove the pump from the engine to replace the impeller, make sure you put the pump back on the same way it came off. This pump will go on with the inlet and outlet reversed causing the pump to not draw in water.
*We have seen this impeller spin on the hub, the flaps looked fine but the internal metal hub was separated from the rubber and was very hard to see.