Mike removing the old impeller
Like most marine diesels, Madrone’s engine is cooled with sea water. The water used for cooling is sucked in from the ocean and then pumped through a coolant-filled heat exchanger before being combined with the exhaust gasses and pushed overboard. The pump that drives the cooling water does it by spinning a rubber impeller with small rubber vanes.
Water pump with the impeller removed
When an impeller fails, one or more of the thin rubber vanes breaks off. If that happens, the water flow from the remaining vanes can push the broken piece deep into the heat exchanger and constrict the flow of cooling water.
New impeller installed in the water pump
So, we replace the impeller inside the water pump as a part of preventive engine maintenance, usually every few hundred hours. We try to do all we can to keep our engine happy and healthy!
