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krudawg · 12-13-2017, 01:58 PM

We are about 10 miles from our destination in Sedona AZ. I'm towing our toad and decide to turn on the dash heat to warm things up. About a mile or so later we pull into a rest stop. We are stopped there with the engine running in neutral for about 5 or 6 minutes. Before leaving I walk around the rig to do a visual inspection of my toad and all is well. We prepare to leave the rest stop and decide to turn off the dash heat off and while turning the switch a creepy sound was heard behind the dash - I'd describe it as a valve trying to return to the closed position, like a vibration or loud clicking noise. The sound kept going for at least 30 seconds. As we leave the rest top I am accelerating to merge in traffic and once merged I reduce speed to 63-65mph. Instantly alarms are sounding with a message of COOLANT HOT and check engine light. I pull over and shut down the engine and work my way to the rear of the coach expecting to see steam escaping or water on the road. To my utter amazement there was no steam or spraying water. I climbed back into the coach and turned the switch on and the temp gauge pegged on Hot. I waited about 10 mins and checked the gauge and to my shock it was showing the first line off COLD. I fired up the engine and drove to the destination keeping an eye on the temp gauge (like I continueily do while driving) and noted that over a period of 5 miles I watched the temp gauge move from the first line near cold to half way up the gauge to slowly dropping back to the first line near cold. Outside temperature for the entire trip was mid to high 60's. Any ideas???

Gordon Dewald · 12-13-2017, 02:01 PM

A guess would be the thermostat.

Outbound · 12-13-2017, 02:30 PM

Thermostat or air in the system?

twinboat · 12-13-2017, 02:58 PM

Thermostat, low coolant, fan controller if equipped.

Franka548 · 12-13-2017, 08:06 PM

My guess would be that there was an air pocket in the heater core and that when you turned the heater on the core filled up and that now your coolant level is a little low. This can cause the up and down temps that you observed.
Frank

Lloyd in S.C. · 12-15-2017, 06:32 AM

I own the same coach. However I have not had this problem. Suggest you setup the information display so that it displays engine temp. See if it confirms the actual high coolant temp digital reading.

I agree with the others.... it does sound like you had air in the system, if that is true I would expect you will now be low on coolant as coolant will be used to fill the air pocket. May want to run it on high idle for a little while (while parked, turn cruise control on, hit set button will raise idle to 1,200 rpms).

L.

gatorcq · 12-15-2017, 06:58 AM

I suggest you post in the correct forum. In either CAT to the Cummins section. By the way, sometimes all it takes is let the engine idle first ti cool down, look at the temp gauge, check the coolant level as maybe it is low and you were going uphill. But please use the correct forum page, this will help you better