Join Date: Sep 2010
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Yanmar 1GM10 Thermostat and Temp Sending Unit
I have a 1GM10. I replaced the strainer, thermostat, impeller, and all hoses after purchasing the vessel last fall. For 3 weeks this season, the motor ran fine at 2400 RPM for extended periods. It was negelected and sat in salt water prior to my purchase. I flushed the engine continuously prior to replacing all the parts. The exhaust elbow appeared slightly corroded, but sound. I started overheating last weekend after running at 2000 RPM for 10 minutes. Pulled the thermostat to check for obstruction (none) and the temperature sending unit to check operation. The thermostat opens fully at 125F. The sending unit switches at 150F. Are these temperatures too cool? Automotive thermostats generally are 160F to 180F (although they are pressurized systems and the Yanmar is raw water cooled and not pressurized). I have ordered a new exhaust elbow to try next. Any other suggestions?