so if my thermostat is doing what it is supposed to do. then why is my truck over heating like this? i know that if i sit for a long time that my temp is going to rise a bit but go back or above the stock temp? that doesn't sound right. now could it be that the clutch fan isn't working properly? or i have to much heat under the hood due to my UNcoated headers? I mean come on, my truck shouldn't over heat like it does for just sitting in a spot for 10-20 minutes, and go back to stock when driving.

 

hey phat - what temp is your truck getting to when you are idleing with the ac on? if it is ~200-210* and you have the stock clutch in the fan then that is normal. the clutch will not engage the fan until it reaches ~195*, so there really isn't any air flow across the radiator, and worse the condensor, until it reaches the higher temp. mine did the same thing last summer when i dropped in the 160* thermo while waiting on my e-fans to come in.