Is this happening at hwy speeds ? I've only had a clutch fan be bad once . It was fine as you describe until forced then would climb . I not only found the increase from applying more gas , but also from cruising over 60 it was very noticeable increase . It was the clutch fan . Put the new one on and never saw the gauge rise above normal after . On the hwy , the fan was not spinning enough to pull the air through , as a result , it starts to block the airflow resulting in the temp rise . That's how it was explained to me . I'd just look for a pick-pull part and try one to see if yields the same

 

If your fan clutch is good you will hear a roar coming from it when you first start it. If you don't then it's bad.

 

I've tested the fan clutch a few different ways. And the coolant looks good. I notice it mainly in stop and got traffic. When I accelerate and let off gas the temp goes up. Then if I'm sitting at light it takes a long time to come back down. But as soon as I touch the gas it starts coming back down fast. I burped the system. New rad cap. Checked the fluid. All the hoses are the right temp. It only gets to about 210 or 215ish but that's too hot for me. And it fluctuates alot up and down. I've tested the fan clutch the ways I know and it seems alright. Maby time for a 180 tstat. With a 195 tstat that's in it. It's running 210 so in theory with a 180 it should be running 195. Right where it's supposed to

 

How did you test the fan to see if it is working properly?
Second you do know that the fan has a heat clutch in it, once the fan reach's the temp it needs it will be real stiff to rotate, once cooled down the clutch will release and spin freely, So I would bet you either have a bad clutch in the fan, Or your radiator is clogged and you are only getting have the water flow you should be getting.. Here is a question for you, Do you even have the radiator shroud on the radiator ? I have to ask cause we aren't there to see for ourself., and one other question Did you change your grill to one of those flat stainless goofing looking inserts? These trucks are real picky on a lot of things, and if you change the air flow on the radiator and keep dropping the hammer at every light or just speeding around you will over heat...


My bet is the fan is shot or radiator is clogged

 

I do have a shroud. And I tested it by heating it up and checking the resistance on the fan when hot. There is resistance when hot compared to cold. How much resistant is supposed to be there. I can still turn it fairly easy. I would like to stick with the stock t stat and fix the actual issue. How hard is it to Change the clutch fan. There's only 56k original miles. I just can't image all this stuff going bad already.

 

If you heated it up and can still turn it easy then the clutch on the fan is shot, replacing them is easy, there is a big nut on the back side of fan get a wrench and a dead blow hammer smack it loose spin off, spin on new one and your done.

 

Okay I'll try a clutch fan. The only one offered in my area at parts store is a severe heavy duty counter clock wise rotation. Is that right? Counter clock wise. And will the heavy duty be too much for the truck? I don't want it to be running all the time

 

Look at how your blades are angled, and determine which way the fan would need to spin to draw air thru the radiator. (as opposed to pushing it thru.) That'll tell ya what direction it spins.

 

No testing needed! No roar = bad. Start it and rev the motor about 1500-2000 rpm, You should hear it. If you keep the rpms up it will go away usually with in a minute(depending on temp).

 

These trucks aren't picky about much and the cooling system sure ain't one of them. I can't even get mine to get up to 190.