2007 Monaco Dynasty TAG 42' side radiator.
Now pass this off to senor moment and maybe engine temp has been fluctuating 15deg has always happened over the years I have been driving the rig but...
last spring I was climbing up I25 towards Santa Fe and notice the temp had gone over 210, stopped to let it cool down and noticed the expansion tank was hissing at some joint and the coolant was boiling.
Made it back to Colorado, bought a new metal tank. NOW..
Climbing up I25 from Colorado into Wyoming I am watching the temp.
It goes up and down with the hills, about a 15 degree range. 194 degrees on the flat and down and up to 208 on the up. I dont remember ever seeing this, or this old guy never noticed.
Reading here, many threads, Thermostat or Temp sensor. The Boiling coolant could have ruined the thermostat, my first though. The Temp sensor for $19 on AMazon, so why not.
ANYTHING ELSE? I bow to you , the knowledge base