My fans work great, I just replaced the thermostat (installed correctly) the water pump is good, it's full of coolant and for some reason it keeps trying to overheat. i have no leaks either but it keeps overheating. I'm stumped... i need some real advice.

 

check the coolant sensor on the left bank head. (right side if looking at the motor) it is just below the exhaust. if it is reading wrrong it would definately be the problem.

 

Did you bleed the system??

 

What year and engine do you have? You first need to determine whether your gauge is telling the truth or not. Has your water pump been replaced shortly before the overheating started, by chance? Older v-belt set-ups used a conventional rotation water pump, serpentine uses reverse rotation. If there was a mix up, it will cause overheating.