Dodge Repair: 2000 Dodge Durango Overheating, upper radiator hose, dodge durango

Question
I have a 2000 Dodge Durango, 4.7, 4wd, that overheated on me the other day. I drove it to work fine in the morning, slightly cool in the morning where I live. On the way home, a ten minute drive max, I got about three miles from home and the check gauges light came on and I was overheating and getting hotter really fast. I stopped immediately and let it cool down for a while, 10 to 15 minutes. It was out of coolant at that moment. I limped it back home and tried to figure out the problem. Noticed immediately, that the upper radiator hose was blown at the "T" where the pressure cap is at. I reattached it at and added water, but it still quickly ran hot again. Local mechanic told me it might be air locked and gave me instructions on how to fix that issue. He said to open the pressure valve and leave it open, fill the radiator with water, crank it and let it get warm and run for 10 to 15 minutes and see if that helps.I did what was suggested, but it was still running hot. But while I was doing that I did notice some things that might be of some use to you. First, I noticed that there was no fluid flowing through the upper radiator hose AT ALL during the course of the attempted breaking of the air lock. Kind of figured there should be fluid running from the hot engine to the radiator to cool off. Second, I noticed that the upper radiator hose was EXTREMELY hot but the lower one was warm but not hot at all. I do not understand this cooling system as the coolant is not poured directly into the radiator but into the overfill. and yet the pressure cap is located on the upper radiator hose. My question is where is the issue? Thermostat? water pump? radiator or electric fan behind the radiator? Second, explain to me how this cooling system works because I have never seen anything but direct pour to the radiator. Thank you for any light you can shed on this problem.

Answer
From you description it would appear that your thermostat is not opening. The thermostat on this vehicle is located at the radiator inlet side of the engine, which is where the lower radiator hose attaches to the engine. The cooling system operates the same way as in other engines with only exception being the location of the thermostat. You still fill the coolant at the cap location and the coolant still flows from the top of the engine, out to the radiator and flows back into the engine through the lower hose. Hope this helps.