I thought I might have had a problem with the fresh water side of the cooling system of my Universal M4-30 engine because it was heating water very slowly. I now think that it is just that the sea water is cold this time of year and it was taking longer than I expected. All was fine with lots of hot water after an extended motoring session at speed as opposed to idling at the mooring. However, it made me think about this side of the cooling system. Presumably, minimal fresh water circulates through the heat exchanger until the thermostat opens. My question is, what drives that water circulation. I know to check the impeller on the raw water pump side periodically, but I have seen no mention of doing the same for a water pump on the fresh water side. That pump appears to be pretty inaccessible on my engine anyway and nothing in the routine maintenance section talks about periodic replacement of an impeller there. So I am guessing it does not have an impeller that needs replacement, but I can’t find anything relevant in the manual. Thanks- Dave
David Knecht S/V Aries 1990 C&C 34+ New London, CT
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