I have an intermittent problem causing engine overheat due to loss of sea water cooling circulation. This is with a Yanmar 3GM30F. I have already checked and claened the sea water strainer, (no blockage), replaced the water pump impellor, (nothing wrong with old one), checked all lines, etc. for blockage. After I get the pump primed and working again, everything is ok. This usually occurs when starting the engine after sailing witha good amount of heal and / or bouncing due to chop. More information.. The sea water strainer is factory mounted high enough above the water line that water will not free flow to the pump. Piping runs from seacock through the strainer to the sea water pump, then to the heat exchanger, then runs to the stean locker and up through an anti-siphon u valve, then back down to the engine compartment and up into the exhaust mixing elbow. Can anyone tell me why the hoses and antisiphon valve, (also appearing to be factory installed), is there? This is not shown on the Yanmar engine cooling diagrams. Also, any other suggestions? I am leaning towards the following... 1) Replace and lube the impellor again. 2) Removed the hoses and anti-siphon valve, piping directly from the heat exchanger output to the mixing elbow. 3) Disassemble and clean the heat exchanger.
Thanks for any suggestions and help.
Thanks for any suggestions and help.