1998 ranger engine temp problem

Summer 2004 drove death valley. 112 at stove pipe wells. no problem. Temp gauge centered all the way across, up and out.

Summer 2005 and 2006 had temp problem in hot weather when air temp over 90 degrees. No noticeable change in symptoms between 2005 and 2006! At 90 degrees go up a slight grade and temp up 3/4 to redline within a mile or two at 55mph. At 98 degrees drive 55 on level and 3/4 to redline. Drive up Sandia mountain, about 3000 feet,on warm day and redline. Drive the interstate at 95 degrees and ok. Slow at exit and go up short rise at 45 and gauge up to 3/4. A/c shuts off in all cases.

Tried downshifting to provide more coolant flow with no effect. Fan works but is strange. Resistance provided by fan thermal clutch is not discernably different whether very cold or very hot. A thermal clutch that seems to do nothing! But there is substantial fan speed when truck stopped and hood up. Since A/C and temp gauge use separate sensors this seems to confirm sensors ok. Replaced thermostat. New hoses. Flushed radiator. Fluid clean at drain prior to flush. No help. Temp of radiator to touch same top and bottom which seems to indicate hot water flow not blocked. Inspected radiator visually and with hose. There does not appear to be any restrictions to air flow. I've tried purging air and replacing radiator cap. No coolant leaks. Problem started at about 100,000 miles. Its a 9 month a year vehicle.

Took it to shop I usually deal with. They took it for test drive on a 70 degree morning and told me there was no problem. Nobody listens! They did comment that water flow seemed ok.

Summer 2004 drove death valley. 112 at stove pipe wells. no problem. Temp gauge centered all the way across, up and out.

Summer 2005 and 2006 had temp problem in hot weather when air temp over 90 degrees. No noticeable change in symptoms between 2005 and 2006! At 90 degrees go up a slight grade and temp up 3/4 to redline within a mile or two at 55mph. At 98 degrees drive 55 on level and 3/4 to redline. Drive up Sandia mountain, about 3000 feet,on warm day and redline. Drive the interstate at 95 degrees and ok. Slow at exit and go up short rise at 45 and gauge up to 3/4. A/c shuts off in all cases.

Tried downshifting to provide more coolant flow with no effect. Fan works but is strange. Resistance provided by fan thermal clutch is not discernably different whether very cold or very hot. A thermal clutch that seems to do nothing! But there is substantial fan speed when truck stopped and hood up. Since A/C and temp gauge use separate sensors this seems to confirm sensors ok. Replaced thermostat. New hoses. Flushed radiator. Fluid clean at drain prior to flush. No help. Temp of radiator to touch same top and bottom which seems to indicate hot water flow not blocked. Inspected radiator visually and with hose. There does not appear to be any restrictions to air flow. I've tried purging air and replacing radiator cap. No coolant leaks. Problem started at about 100,000 miles. Its a 9 month a year vehicle.

Took it to shop I usually deal with. They took it for test drive on a 70 degree morning and told me there was no problem. Nobody listens! They did comment that water flow seemed ok.

I have a 99 Ranger that was having problems with temperature. I live in the South so its very hot here. I noticed that during the hotter parts of the day, if I was driving with the AC on and having to stop in traffic that the temp would slowly start to climb towards the overheat area. If I turned the AC off, it would start to go down.

A mechanic friend told me it was the fan clutch. I changed it out yesterday and I guess we will see if it works or not. I did notice more fan noise when idling after the change. I will post more as I find out, but i bet you might start looking towards that.

There is supposed to be a plastic seal strip at the top and bottom of the radiator ... that keeps trash from getting sucked between the radiator and the ac condensor ... check to see that these strips are in place and doing their job. Make sure this area (betweem the radiator and condensor) is debris free.

Also if you've never replaced the water pump, you might consider it. Just a little wear/errosion of the tips of the pump impeller vanes will greatly affect its performance.

Well, today the truck almost overheated, so the fan clutch didnt do it. I am changing out the thermostat, and flushing and refilling it as I type. I will check those areas and see if there is any debris there.

God I hope it isnt the water pump. Those things suck to replace!

Exterior of Radiator is clean, including between the radiator and A/C radiator.

The fan resistance is no more than an ounce or two at the fan tip. I don't know how it actually works. Could be a combination of viscosity and trubulent flow or ???? I'd be interested in knowing about fan turning resistance, hot and cold. How about the one that was just replaced?

The truck has a little over 126k and I plan to keep it for another 50 or 100 or so.

I think I'll replace the fan and water pump and think of it as preventative maintenance! The problem could be a combination of tired pump and fan -maybe more.