Engine temperature

[dougstinchcum]

My 315 turbo Yanmar runs at about 175 degrees Farenheight while crusing. After trolling for 30 minutes or so at idle speed the temperature drops to about 135 degrees F. Should the thermostat hold the operating temperature closer to 175?????

[Denis]

I don't have any specific information on Yanmars, but a thermostat should keep the engine at optimum operating temperature. The engine temp. sensor should be reading the block temperature and the thermostat should open and close to let the cooler water from the heat exchanger in to regulate the temp of the block.

[chiefrcd]

Doug, I have the same issue and after trolling a few hours when I go to run up the engine, it's like a old city bus...black smoke for about 30 seconds, then it's fine. I'm sure the engine is too cold after trolling.

[dougstinchcum]

I'm going to talk with Lew Grimm about this. I'll let you know what DYC says. Maybe we'll be elping each other change thermostats.