Bizarre overheat

[fisherman]

Local boat, new engine, always a bit warm, came back in one day thoroughly hot, After much head scratching, found there was an airlock around the fresh water circulation pump, which of course won't prime. Cured with force feeding from a hose. New one on me. Beta 50 or so hp.

 

[sarabande]

If it is an impeller style pump, any damage to the vanes from the heat ?

 

[jwfrary]

Local boat, new engine, always a bit warm, came back in one day thoroughly hot, After much head scratching, found there was an airlock around the fresh water circulation pump, which of course won't prime. Cured with force feeding from a hose. New one on me. Beta 50 or so hp.

Fitted with a calorofier?

 

[fisherman]

Fitted with a calorofier?

Goodness me no, in a fishing boat?
Fresh water pump is metal vanes, same as any car.

 

[Blueboatman]

The airlock may be a symptom only
Overheating raw water /heat exchanger circuit ‘cooking’ the freshwater side I would want to eliminate first .
or the freshwater side is pressurising somewhere ???
Or poorly fitted hose or dodgy thermostat/incorrectly reinstalled ..
I would measure the through flow of sea water first at rpm

 

[fisherman]

The head scratching involved stripping the heat exchanger, checking the pipestack, thermostat, and the sea water is going through fine. It was just the engineer could see no fresh water flow across the header tank, even with a hot engine. Began to think the pump vanes which are pressed on the shaft, might have come loose. That's when he found it was bone dry. Engine has been fine since.