Do you hear a gurgling sound from under the dash after shut down. You should have mentioned this before. I can take you thru the "air pocket" removel process. But you have to drain it from the block as well as the radiator and refill -Burp/Bleed.

Make sure your water pump isn't weeping first.

 

 

Didn't catch the overheating problem until you responded a few posts down. With 275K on the motor and original fan clutch, I'd be willing to guess its probably past its service life. My 1992 Flareside went out at about 120K and when it did, I noticed the temp rose higher than normal sitting in traffic. It will also affect the efficiency of the air conditioning at idle. If you do decide to change it, you will need a special tool to keep the pulley from turning while you unscrew the clutch from it. I made my own from some spare flat metal after I realized that I could not hold the pulley and turn the wrench at the same time. You said the fan spun freely, where when its cold should have some resistance on it. If you check it before starting the vehicle in the morning and you are able to spin the fan with little effort, I would say its bad. For reference go to an auto parts store and ask for a fan clutch for your vehicle. Turn the clutch and see how much resistance there is and then compare to yours. Mine spun about 1/2 to 3/4 turns easily while still mounted to the vehicle. The one I replaced it with moved about 1/8 of a turn with resistance. This is about all of the advice I can give and its from my own experience. I am not a professional mechanic but I do all my own work except for automatic transmissions and major engine repair. I'll try to fix just about anything to save money and my philosophy is 'If its already broke, how much more broke can I make it?' I've spent a few more $$ a couple of times because I messed up something else in the process of a repair but its all a learning experience. I also invested in a subscription to Alldata for all my vehicles and have gotten on forums and asked questions like you. I figure if I am having the problem, someone else probably is also. BTW when I changed both my Bronco and Expedition, the instructions recommended changing the water pump as well but I chose not to.

Hope you get it fixed soon.