overheating 2002 S10 Blazer 4.3L
 

Last year my son was driving to west coast and radiator blew, tank split on the side. Local repair shop replaced radiator. He stayed about 2 months and then headed home, started experiencing overheating limped in stopping and letting cool and replacing water as needed. Since I've replaced thermostat (twice), water pump, fan clutch, all hoses, ECT sensor, checked for blockage in condensor/radiator, radiator cap, no oil in water or water in oil, no white smoke from exhaust, dumped coolant and burped to get air out of system. Truck overheats mostly on open highway when AC is on, turns it off and it will cool back down, cools fine while sitting still at idle. Any thoughts on what else this could be.

have you changed the rad cap? sounds stupid, but i have seen a guy replace his whole cooling system and the rad cap was bad

yes, did that also. Did just find out that he had been using yellow prestone instead of dex-cool which means it was probably mixed. I've heard stories about that guming up the system, starting to wonder if maybe the flow in the radiator may not be what it should. Just working on flushing the system now to see if that helps.

Anybody else had any expereince with that ?

not myself, but i know it causes problems, try draining it and running strait water for a day or so to really flush it out, then put the dex-cool back in it

ok, thanks, flushed it out a couple of times and just ran it, heats up to about 210-220 but stays there on open highway under load. Flush may have helped, also need to make sure I got all the air out of the system and see what happens. If not I'll go back and flush it out a few more times.

thats still pretty high for my liking, what degree thermostat was put in it?

Put a 195 degree in which is what was spec'd. Sitting at idle it will stay right around 195 until you get it out on the highway with a load, starts going back up then.

i would try a 165 on it, may help a bit, 1 more thing, is there a lot of crap in front of the a/c rad? and also does the trans get hot too? a trans cooler may help things. could also be an o2 sensor causing it to run lean or a bad cat, could be many things now that the coolant system has been replaced, but i would try the cooler thermostat, i only run a 195 thermo when it is winter (quicker warm ups in -30)

ok, thanks, I power washed both rads and cleaned out everything in between. Hate to throw a cooler on, used to run fine but something has changed. Thought about the cats but he's not getting any o2 codes indicating sensors maybe bad. May try the cooler tstat and see what happens.

sounds like a good plan, 195 deg thermostats are only for winter i have met people who dissagree, but my engine runs real consistant with a 165 in it