I've noticed my temperature gauge does not work. It stays at about 110 even when off or unplugged (I did start it with the temp sensor unplugged and it did nothing but make the check engine light turn on which prompted me to make a trip down to Advance Auto Parts to have them reset)

The engine compartment feels hot after a less than 5 mile trip. The top radiator tube thingy (excuse my very technical description ) is hot but the bottom one is not hot at all. I bought a new thermostat to see if that helps but do you think it could be the:

1. Thermostat
2. Temperature Sensor
3. Temperature Gauge
4. Something more technical than a "thingy"

Any ideas? Ive searched this forum but could not find anything applicable to my situation.

 

Everything sounds normal to me. Are you losing coolant? I would put an after market temp gauge on it if your not going to fix the stock one. The only thing that my be wrong with it is the sending unit. The part connected to the engine. Get a book or two on your jeep. It will help you trouble shoot most problems.

 

After much checking I think my thermostat is stuck on the open position. I need to replace it due to a road trip but I'm limited by time and $$$. I know it's recommended to do a radiator flush but is it absolutely necessary?

It's a 1996 4.0l HO and the thermostat is up on the top of the block... If I don't have to do a flush, what's the minimum I can drain the radiator so I can replace it? Or do I even need to drain it at all?

 

Get a new T-stat and T-stat housing gasket. About 6-7 bucks at Autozone. Don't drain the radiator at all. Just pull off the T-stat housing. You're right, since it is on the top of the motor you actually will lose very little water. Maybe a pint to a quart at the most. Install your new T-stat and T-stat housing gasket, top it off with water, Let the motor run until Normal Oprating Temp. so you know your new T-stat is working and that it in fact fixed your problem. Then happy trails

 

A bad thermostat would not cause your gauge to stay at 110* whether the vehicle is on or off... This is either a gauge problem, a ground/wiring problem, or a sender problem.

Usually the gauge will 0 out when there is a problem. Perhaps the gauges itself is stuck.