I bought a 2003 chevy duramax a couple months ago hauled a couple of cars with no problem I have now installed a edge attitude with juice programmer and a cold air intake and was hauling a car and it started to over heat I was running around 70 so I slowed down and the temp droped On the way home I had 2 toyota trucks on the trailor and it over heated agian so I unloaded one and it dropped but still stayed hot .Once the truck wasnt pulling anything it runs cool any help would be great. The truck has 164000 miles and is a duelly with cat deplete

 

Is your fan clutch working alright? a/c condenser, intercooler, radiator fins clean? Coolant level correct. What setting are you running the programmer on?

 

I was running in the tow mode on my edge and had the tranny in tow also The first two cars I hauled I didnt have the edge could it be over fueling my truck? I will check the raidator and clutch fan but if something was wrong with them wouldnt it overheat all the time?

 

not necessarily.

i have been running for the better part of a year with out any fan at all and it doesn't over heat (except once). granted it will run a little on the hot side when driving below 30 mph for extended time. i dont tow much so i have been able to get away with it like this

towing puts a much greater demand on the cooling system. when you add a programmer and increase the fuel the cooling system now has to dissipate the extra heat generated and can overheat easier.

i would, as suggested above, check the cooling system and maybe even a coolant flush and replace the thermostats.