[Barry Rooker]

My 2001 DD60 was running a little hotter each year after having been a steady 180 degree machine. Then last year in April on I-40 it hit 230 & I knew that was just too hot. Anytime the fan went from it's standard 25% to 100%, the temp gauge needle would plummet. Yes, I'm told by Newell that my hydraulic fan runs at 25% at a minimum and goes to 100% upon default.

We re-cored the radiator this summer and it became an "ambient + 90 degrees" machine. Nice. But on a test spin today, with 95 ambient, it hit 210. And stayed there. Tapping on the new gauge didn't help. Infra-red gun shot at the DD60's thermostat housing confirmed the temp.

Now 210 isn't bad, it's fuel efficient in fact, but there's no margin for hotter weather or pulling a big grade. My fan used to come on at a lower temp. There's gotta be a temp sensor or switch (in the DDEC programming?) feeding that Vickers solenoid in the chunk of anodized aluminum where the hydraulic lines come from the pump & go to the fan motor.

Any ideas?