99 Ram 5.2 temperature rising when at a idle. Goes down when I start moving or even if I tap the gas. Pretty sure it has a 180 thermostat in it, truck usually stays cool since I've bought it. It will move up to 210 sometimes a hair past it after idling for 5 minutes.

Ive searched on the forum before asking so bare with me if the answer is out there! I did the newspaper test on the fan clutch after letting it reach operating temperature it tore the paper all up so it passed that. When i turned it off, the fan spun freely by hand with no resistance and it would keep spinning. After it cooled completely down it had a little resistance when turning the fan and wouldn't make a complete spin after it has cooled. Radiator is brand new as is the heater core, I did notice when I start the truck after letting it sit for a long you can hear the heater core filling up quite loudly and obnoxious. I'm guessing it's either the fan clutch or air in the system. Also both hoses are hot when normal temp range, top hose is really hot and bottom is semi warm.

 

It could be air in the system as you suggest, possibility from the new radiator install. I like to drill a small hole in the thermostat so that doesn't happen. If you did replace the thermostat recently, you could do that along with the test of the thermostat in a pan of hot water with a meat temp gauge. I have seen some guys just pull off the top hose to let the air out.

 

If it spins freely when the engine is hot, it's bad.

 

thats what I thought just wanted to make sure!