Hello all.
I'm hoping someone can point me in the right direction.
2002 Ranger 2wd 2.3L 5 speed 140K miles

About 3 months ago everything was fine but then one day driving to work I had the temp gauge shoot immediately to hot. The engine shut off and I coasted to the side. I immediately restarted and all was normal. Finished my trip to work. It didn't repeat until about a week later. Again..
same thing. Restart and normal. No further problems until...

About 2 months ago I went out that morning to warm the truck up. When hopping in I noticed the temp gauge hadn't moved and I had no heat. So I figured thermostat. Low on funds I had to deal with it for the next month. It was running fine just no heat until about 2 weeks later. I noticed that whenever reving the engine or depressing the clutch the idle would stick at about 2K for a few seconds before coming back down. Decided to park it for a bit until I could work on it......

Finally had time to work on it. Did a coolant flush and replaced the thermo assembly. All seemed fine. Temp gauge was normal and I had heat but the idle issue was still there. Took it for a test drive but almost as soon as I started down the highway the temp gauge shot up and it shut off. Same as before but more frequently. If I restarted it would be normal range but a mile down the road it would repeat itself. Local mechanic said my radiator was clogged. My next step was new radiator and hoses. This changed nothing. Still pegging the gauge and shutting off. Once I pull over and restart the gauge shows normal right away. Still also have the sticking idle problem as well.
NOTE: I can not replicate the overheating problem in my driveway. It will not do it sitting still. Hours of idling and holding a 2000 rpm idle have not caused it. Doesn't do it until I hit the road although the idle issue is there all the time.
I dont know where to go from here and I hoping someone has a suggestion.

 

2002 Ranger will have a 2.3l DOHC Duratec engine which is much different than the 2.3l SOHC Lima engines used in earlier Rangers

So just a heads up if you Google "Ranger 2.3l engine", you will get conflicting information because there were TWO different 2.3l engines

For your engine there are TWO temp detecting devises
CHT(cylinder heat temp) sensor located between cylinder 3 and 4 spark plugs on top of engine, this is ONLY used by the computer, not the gauge

ECT(engine coolant temp) SENDER, not sensor, its on a metal tube behind the head, has 2 wire connector, this is ONLY used by the dash temp gauge

You never mention checking the coolant???????
I would assume you did check it cold and it was OK?

No heater would mean no coolant circulation thru the heater core in the cab, so either water pump is failing, coolant was low or heater hose/bypass/core was clogged up

Is the heater working now?

Shutting off means the CHT sensor is reporting over heating, not just the ECT sender
So either over heating is real or both devices are bad, high odds on the later

So was the over heating real?
Did you open the hood

Water pumps can have impeller shaft failure, its when the impeller/blades come loose from the shaft so don't spin at engine RPMs, it spins slower so at idle its fine, but when under a load circulation is not fast enough
Same symptom if impeller blades get worn down from electrolysis, OK flow at idle but not enough flow under load
And this symptom could also be confused with clogged radiator

Also, on the rad support will be a fan belt diagram, check it closely, I have seen fan belts routed incorrectly, so the water pump(an fan) is turning backwards, still works at idle but not when under load

 

Thanks for the reply.
Yep...coolant has been fine every time its happened.
And after changing the thermostat my heat did return. The reason the mechanic suggested the new radiator was based on feel. Hot on the passenger side. Stone cold on the driver side. But since changing the thermostat and radiator my issue seems to have gotten worse. Before I could drive it...maybe happening once a week but now it happens as soon as I get going down the road. So I ended up limping it back with it going hot, cutting off then after restart gauge was back in the normal.
Owned the truck for 2 years and this is the first problem I've had with it but I did run out and check the belt. It is routed correctly.
As to the overheat question? When I looked under the hood after it happened......Top hose was hot but not to the point I couldn't grab it. Reservoir was halfway between min and max. No coolant being blown anywhere.

 

I would change the ECT sender on the metal tube behind the head
It runs from passenger side and around to the back of the head, ECT sender is there, should have red/white and black/white wires attached

On the 2.3l this sender is also connected to computer, its not on the V6 models, so if it was bad it could shut off the engine