Armyguy and mech cb, thanks for the extra info. I hadn't really thought about the fan clutch being a possible culprit (as I mentioned before, I've seen the fan turning when I had the engine running and the hood up), but it might explain why my temp gauge goes up while I'm sitting idle at any of the many five-minute stop lights around here...

 

I know it has been over a year now, but I wanted to follow-up and put some closure on this thread... Over a period of several months I replaced the radiator cap, had a flush and fill done along with thermostat replacement, and had the fan clutch replaced. The overheating continued on an intermittent basis, but was very much related to the outdoor temperature (generally problem-free during the winter months, but any day over 90 would be a bad day). I recently returned to the shop where I had the flush and fill done, and after some checking around they determined I had a crack in the radiator (one would think they could have detected this during the flush and fill). I had them replace the radiator, and the problem now seems to have been resolved. The temperature gauge is staying in the 210 range even with outdoor temperatures in the 90s and or 100s.

 

I have this same problem. The radiator has been replaced, radiator cap has been replaced, I haven't flushed the radiator yet, but I will and I will have the radiator checked, as the previous owner had it done about 5 yrs ago and she was ridiculously hard on this poor truck. It's a 2000 and I have already put over $4000 in repairs into this vehicle. Thanks for all the good ideas.
Did you have your idle drop? Or just overheat and die? Mine drops RPM, I have to put the truck into neutral and goose the gas pedal to keep the truck at idle, to limp it out of intersections when this acts up.

 

In my case the idle would remain fairly consistent whether the engine was cold, warm, or hot, so I can't help you there.
About the only major cooling system item I didn't replace before this problem went away was the water pump. While it's probably a stretch to think that bad bearings on a water pump might lug the engine, I still might look at that before tackling all of the electronics involved that could affect your idle speed...

 

the way i check clutch fan is when engine reaches temp 200 - 210 degrees by the way thats normal. put card board in front of radiator and block air flow with hood closed and car in park and keep an eye on temp and dont let it go over 220 and you should here fan start turning then shut off engine and open hood and try to turn fan if you can turn easy replace clutch

 

Hey guys, I was having the same problem as Canyon until this morning. I think it may have reached a head. On my way to work the water temp was going from 260 to 0 and back. When I stopped and popped the hood there was steam coming from what seemed to be the fan clutch. Or that area any way it is raining this morning, and I could hear a sort of ticking sound from the engine when I accelerated. I still have coolant in he system from a drain and flush I had done a few months ago. I don't know if its actually circulating though. So I guess I will change the thermostat, radiator cap, fan clutch, and water pump and see if this fixes the problem. Will post back when this is all finished. The only problem now is I have to get home...

 

blazer073,
If you do follow-up on this, please do so by starting your own thread rather than this one. Thanks.

 

Continued in https://blazerforum.com/forum/engine-transmission-35/engine-cooling-system-problem-48346/