John Deere 280 II overheating

[pnhigg]

New here. I have a John Deere 280 series II machine that has recently started running warmer than I'd like. If the machine is operated at or near full throttle the temp will slowly (over 30 minutes) move from straight up on the gauge to over near the red. If the machine is let idle or fast idle the temp with move back to normal gradually (about 5 mintues). It does not seem to matter how hard the machine is being used, as yesterday I simply moved some pallets a long distance and the machine was run at full throttle, but other than it moving itself, it engine was under no significant load. During that time the temp had moved to about 1/2 way between straight up and the red. What I have done: removed the radiator and flushed it. Fins are clean top to bottom. new thermostat removed water pump as the impeller is plastic and I wondered if it had been damaged. dealer mechanic said it was fine (looked good to me as well, though was simply a visual inspection) Using a laser thermometer on the in and out hoses on the radiator, there is about a 50* drop in temp from what goes in the radiator to what comes out. Hoses are not collapsing Coolant is a 50/50 mix and is full fan is not slipping as well as I can tell (no noise, and it blows a lot of air through the radiator and out the back of the machine.) Hydraulic cooler is clean as well. I am not loosing coolant Does anyone have any suggestions. I cant think of anything else that might be causing the engine to heat up as it is. Any help is greatly appreciated. Thanks in advance Patrick

 

[skidsteer.ca]

Patrick
I'd say try a aftermarket guage in the motor and see if the factory one is lieing to you.
A 50 degree drop across the rad is pretty good rad perfomance. My 773 bobcat has a wiring glitch that caused the guage to read erractic and to the high side, a gremlin I never could find.
But anyway thats my suggestion, you may have a guage problem not a temperature problem.
Skidsteer.ca