After reading several threads regarding operating temperature problems I went out and ran my '90 non I/C (with vertical flow radiator vs. crossflow of I/C trucks) truck up to temperature. Air temp here is 92 deg. at the moment. Per other threads I shut it down and put my hand on the radiator. Definitely felt a temperature difference as I moved around the radiator. Coolest area was in front of the fan toward the driver side. don't have temp sensor but temperature differential was significant. Do you agree likely partially plugged radiator or would area in front of fan blades naturally be cooler due to fan action? Hoping for opinions before I pull radiator and take it to shop. Thanks.

 

Is your truck running hot? What about when you're towing or under a big load? Depending on the baffles in the top of the radiator it's possible for the coolant to flow more in one area than another. I wouldn't worry about it unless it's overheating.

People tend to worry about running hot too much. Running to cold is actually worse because it costs more fuel. When I got my truck somebody had gutted the thermostat. I couldn't get any heat out of the heater at all. Put in a 190 thermostat and it's been running fine ever since.

Edwin

 

@edwinsmith - To date has not overheated. Have not towed or hauled heavy since operating temperature increase developed. Since purchased has run consistently on the third line of four delineating operating range on factory gauge and climb a little on grades or towing. Now operating on rightmost line of operating range of factory gauge and climbs to "H" line on grades when empty (have not towed since this started). Has never spit coolant, nor have I heard it boiling. Heater is hot, and on full fan does bring temp down some. At it's hottest, idling for 10-15 minutes returns it to third line of operating range. Maybe paranoia on my part, but odd how it was one way one day and seemingly different another day with no progression. Thanks for the reply by the way.

 

If you've always run proper coolant in it I'd suspect a flaky thermostat before the radiator. Cheaper to replace that than to have the radiator rodded. If that doesn't fix the problem you can always go the expensive route.

 

Problem resolved - changed out radiator which was definitely partially clogged first. Did so because it took until late yesterday for my thermostat to arrive. Had a backup radiator so put it in. I now have consistent temp across the entire core. However was still running at an elevated temperature but with the increased flow I could literally control the temperature increase/decrease by pushing down or lifting up on the throttle pedal. This was so noticeable that the only other conclusion was the thermostat was stuck open, which it was. So to poster Edwin, you were right on. But given the radiator was 27 yo and at least 50 % plugged based on the hand on the core temp test, I'm glad I did both. Truck now runs on the second line of operating range of factory gauge which it has never done since I owned it and gives me a lot of room for temperature increase when pulling heavy and or hills before I get past the operating range on the gauge up to the "H" mark. Thank you all who responded and prior posters who clued me in on the core temp hand test !!

 

Assuming your gauge is the same as mine that's exactly where mine runs unloaded on the level. I seldom run the A/C so far this spring. Waiting to see where it runs this summer since I haven't had the A/C fixed before now.