1999 XLT SOHC - Water Pump or Thermostat

[slaughterrt]

Hey guys. Thanks in advanced for your help. Driving home from work today, I had to pull over because my Explorer started to overheat. The vehicle went from Cool to Hot/Overheating on the temp gage in a matter of a couple miles. I pulled over and popped the hood, only to notice our favorite burning coolant smoke. Also saw that the pressure built up in the coolant reservoir because the cap had popped off and coolant was spilling over everywhere...very messy. I also could hear a gurgling sound coming from the radiator (assuming this was the coolant back flowing into the reservoir). After further inspection and cooling down the engine, I didn't see any signs of leaky hoses or leaks from anywhere else. All of the coolant overflowed from my reservoir. My googling has narrowed it to one of two culprits: either the water pump or thermostat. Is there any quick way to diagnose which one is causing the problem? Keep in mind that I am about 30 miles from home and would prefer not to get a tow. Will do what I have to, but any advice would be helpful.

 

[1996xlt]

My guess would be thermostat most of the time when they fail its in the closed position keeping the coolant from flowing where its needed. The reason I say that is if it was the water pump (if it seized) you would've heard the serpentine belt squealing followed by the smell of burnt rubber (ref: belt) in addition to coolant.

 

[96whitesport]

Pull the stat, refill with water or coolant, start it and see if it runs cool, if so drive home and monitor your temp, this would avoid towing. it also may throw the CEL for low engine temp which is no biggie