Hello, I recently purchased a pretty nice 97 Ranger 4wd extended cab as a work vehicle. It runs good other than running hot. It takes a little while but the temp slowly climbs to the top of the gauge and even sets off the "check gauge" light. It will fluctuate when it gets that warm and cools down a bit but it is something that needs to be addressed. If it runs just sitting in the drive the temp does not spike, only when in motion and under load. I'm thinking of starting with the thermostat and cleaning the radiator fins. It's been cold here in Cleveland and I assume this will be a bigger issue when the weather improves.
Truck is pretty well cared for and has 105,000 miles.
Thanks, Steph

 

Your thermostat is 29 years of age.
As you said, the radiator might be dirty (externally clogged) but that doesn't jibe with overheating occurring while sitting.
Similarly, an internally clogged radiator would be the same, no?
How does the coolant and coolant reservoir look?

Maybe the water pump's vanes have corroded away?

Extremely slipping belt?

Do get back to us.

 

Yes, all that seems to make sense. So I guess I’ll start with the easy stuff (thermostat) and move from there. I never considered that the vanes in the pump may have deteriorated.

 

I want to add, check your fan clutch. If it's non functional, everything you described will happen. Even while driving, your not getting enough air through the radiator. You can Google "testing clutch fan" and save me a ton of typing lol, but I would start there.