How Hot is Hot?

[George Fletcher]

I was recently at a Hunter rendevous and the Yanmar representative stated the the 4JH, (mine is a turbo), should run at a water temp of 165 degrees.I have had the boat for two years and the temp gauge reads about 175 degrees at 2,800 RPM cruise. At 3,000 RPMs the temp rises a couple of degrees to about 180.It has been this way since day one. The Yanmar service reps in San Diegoc had the boat out at high RPM cruise a year and a half ago because of a complaint on excessive soot on the stern. They made no metion of any abnormal temp indication.They also checked the eng/prop combination and it was found to be correct.Is this a normal indication? Is the wrong thermostat in place or is it defective?Or is my temp guage out of calibration with the thermostat?What to do, if anything?

 

[Gordon Torresen]

Hot heat

If your temperature gauge goes anywhere and stays there no matter how hard the engine is run, you are in good shape. The absolute reading can be found but it is somewhat immaterial. If you truly run at 180F, that's great. Diesels like to be hot but the cooling system has to put a cap on the heat.

 

[George Fletcher]

Thanks Gordon!

Thanks for the response on the temp of the cooling system.If 180 degrees steady at high cruise RPM is OK then,I'm cool!Thanks again.