on wednesday i drove from pueblo co to denver co about 150 miles and about 100 miles in my temp fell to the first line on the gauge it was pretty cold maybe 25 degrees so i was thinking i might just need to cover my radiator for the winter but i also think my thermostat may have got stuck open but im not sure cause this was the first time i drove the truck in those cold of temetures so tell me what u guys think by the way the truck doesnt run funny or anything the only problem was the heater wasnt getting verry hot

 

Your thermostat probably has stuck open.
If you get a new one, pony up the $$$ and get it from Cummins.

Mark.

 

it should only be like a 15 dollar part from napa

 

Don't waist your time, get it from Cummins the first time!