My 1993 ranger 4X4 5 speed with the 4.0 V6 overheated in a drive-thru the other day. I started driving home because I don't live far and within a minute or two it was back down to operating temp. I checked my coolant and the level was fine but it was very very dirty. The oil level also seems to be ok and there is no coolant in the oil. Since then I've done two cooling system flushes and replaced the thermostat. I've noticed it only overheats when I leave the car running but I'm not driving. I checked the fan and it does spin when the car isn't driving.

 

Seen some interesting discussions on how a Thermostatically Controlled Fan Clutch works.

Yours spins by hand. Good....not seized.
However, they spin when cold. You don't need a fan when coolant and engine is cold.

When coolant/engine/radiator/water pump hub get HOT, that's when you need the fan.
So, spins cold.....drive it through the drive-through again (or whatever you need to do to get it HOT), pull over, shut if OFF (keys in pocket so you KNOW it's off), pop the bonnet, grab the fan and spin it.

It should not be locked, but the viscous fluid should have engaged to REALLY throw a damper (joke) on the proceedings.

It it just spins when HOT, it's shot.

 

The fan does spin by hand when cold. I'll check right now to see if it does or doesn't spin by hand when it's warm. It does seem like one of the previous owners has/tried to replace the fan clutch or water pump and messed up the nut :/

 

Ah, yes. The old hammer/chisel when the pipe wrench didn't work. Not the fan clutch, most likely water pump, because they'd have known which direction the threads went when putting it together, so no hex damage.

 

And you'd best locate a new fan blade, soon. That one is about to plant itself through the bonnet (hood).
Personally, I wouldn't get myself in line with that blade with ERHO (engine running hood open).
Not pretty.

 

Damn, I didn't see those cracks before :( I guess I'll just order a new fan blade and water pump/fan clutch assembly.