My 2500 has over 223K and was just wondering about changing out the T stat. Changed coolant at 100K IAW owners manual. I've notice lately the truck warms up rather quickly and climbs above the normal range then drops back down in the cooler weather. Wondering if the T stat is sticking. Since I like to practice preventative maintenance I'm leaning toward changing it out. Anyone else with similar mileage experience this?

 

Tstat is the easiest thing to replace on these trucks. I replaced mine with the colder temp version.. 180F I think it was ..

I get hotter than I used to as well, I think my radiator might need to be replaced..

 

i changed mine when it started to do what you are experiencing, but don't get one from any auto parts store. use only one from cummins , it will cost more but it's worth it