6.4 hemi thermostat

[Skyline]

my 2018 2500 tradesman 6.4 just under 10,000 miles. Over the last few weeks I noticed I have to constantly turn the heater temperature up and down . So yesterday change display to read temp was 18 f. Out side driving on rural highway at 55. The temp ran up to 217 tstat would open temp drop to 182 sometimes only a low of 194 Went by dealer had a tech go for ride with me he says temp range is normal Seems a wide range any one know how to find the spec for open and close temps. Thanks

 

[Liquid]

My 2015 2500 6.4 is doing the same thing. Brought it in and dealer said it's a common problem. So much so that the thermostat is backordered at least a month... That's not good for northern Minnesota!

 

[68PowerWagon]

Yeah my 16 has a wide range too. On cold days it will run up to 205-210 & then run all the way down to about 178. I just thought that they maybe designed a larger coolant system than they actually needed. So it is staying open too long? Usually when a tstat goes bad it stays shut & you over heat. Sounds like it might be doing the opposite. I have noticed even in the summer it swinging pulling a load. Just not as dramatic as I mentioned above.
I posted last week that my heat does not get very hot until the ambient temp is in the 40's or above. This might be the issue with mine as well.

 

[Skyline]

Thanks for the replys at this point my dealer won't do anything the tech said they usually fail in open positions