RGraham, I have a JD 310SG that is doing the exact same thing. Did you figure out what was happening with yours?
What I'm seeing is after a few minutes of warm up the temp gauge begins to climb to the top.
Coolant in the radiator is warm, not hot. I can take off the cap and put my finger in it. But gauge shows very hot.
Levels seem right.
I haven't done anything yet, but am figuring on replacing thermostat and sensor.
I kind of suspect the sensor since it runs fine doesn't seem to be overheating, although of course I haven't run it long.
What do you think?
rScotty
Well, I got it fixed and thought I'd share the results so as to help anyone else with the F450 error code and erratic gauge readouts. It always ran fine, but eventually the temperature gauge would climb to max immediately upon starting the backhoe. That's when I knew something was wrong.
I changed the thermostat sensor (old one was OK), checked the thermostat operation with a thermometer (opens at 180F), and then traced all the wiring for bad connections & shorts.
The standard procedure for resetting the error code wasn't working on my dash readout either.
Went to talk to JD dealer and they said it was probably the engine controller. They saw it a lot on SGs that have the engine controller in the engine compartment where it gets vibration, heat soak, and fluids.....but never at all in machines that had the engine controller in the cab as later models had them. It is roughly a $1600 part & a charge to re-program the new one for my machine. There is also said to be a wiring harness that allows the new engine controller to be moved into the cab where it is on newer model 310s. So I figured I'd consider doing that until I found out that the harness to move the controller costs as much as a new controller does. it is the same price as the controller all over again.
BTW, the engine controller also controls the injectors....but that function seemed to be working fine on mine. The only obvious symptom was the F450 error code that couldn't be erased and strange temperature gauge readings.
So I went home and disconnected the engine controller, cleaned all the terminals, checked the wiring again, and reinstalled it. Everything worked fine for about ten minutes and then the gauges went wonky again.
I elected to have the service truck come out and replace the controller. It's an upgrade; the old one is worth a $200 core charge. Replaced the main hydraulic suction hose at the same time and new JD trans/hyd. fluid. Bill just short of $3K. Everything works like new again and the panel readout in the cab is working normally.
rScotty