Ok here we go. First off I will start with what is on the jeep. I have two fans. One electric and then the stock fan. Overflow tank is still holding coolant and I dont think needs to be replaced. I have a new stat (and yes it is in the right way)lol sorry I know people that have put them in backwards. New water neck for the stat. Radiator cap is still holding preasure as well. Now I know I need new hoses cause they leak but they are not busting. But with all that I am still running hot. Sometimes even in the red but it will jump back down sometimes back to 210. Now anyone have any advice please let me know.

Dave

 

Are you sure it is running hot and just not the gauge showing it is hot? Miine was running hot and I had no heat. I pulled the water pump and found I didn't have much left to my impeller. Might be a partial clogged radiator or maybe low on coolant or an air bubble.

 

What year is your jeep and what kind of system is in it? I had an 89 with a closed system I think. Had a problem similar to yours. It'll be hard to explain on this but really the hoses on the outgoing sign of the thermostat were empty, so the thermostat just had an air bubble in it. Thus it was not reading any of the hot coolant that was flowing through the engine and so I always over heated. To fix it I had to detatch that hose and fill it with water/coolant and quickly attach it with out spilling all the water. Let it run till it over heated and then I had to continue to do this until the entire system was full again. Hope that helps. Anyone else with any input please add.

 

This happened to me over the summer. When you changed your tstat you may have got a air bubble in your cooling system. If so, burp the cooling system and you should be good. It could also be a bad water pump or your rad. is shot.