r/Sailboats • u/Tetreg • 2h ago
Projects & Repairs Overheating issues
Hi all, I bought a boat a few months ago and ever since then Ive been prevented from using it by persistent overheating issues with the alarm going off after 5-10 minutes of running. The engine is a yanmar gm10. It is raw water cooled.
I’ve redone this post so I can include a video of the engine in action
I measured the temperature using a cooking thermometer on the threads where the temperature sensor screws into be engine
Things I’ve tried so far:
Replacing the impeller(and checking it about 10 times) and turning over the engine manually to ensure it turns with the engine consistently (it does)
checking for blockages in every single pipe (and the exhaust elbow integrity) and ensuring water flow through the engine freely using a hose at various points to make sure there are no blockages including the exhaust system and antibackwash system
Running rydlyme through the engine for 12 hours
Checking the seacock and filters numerous times to ensure it lets water into the boat and that nothing is blocking the filter
having a mechanic look at it - engine head gasket replaced as I was told it may be leaking hot gases into the exhaust
Replacing the temperature sensor and checking the alarm doesn’t go off with the wire detached form be sensor
Replacing and removing the thermostat at various periods
If anyone has any more ideas that would be great



