High Radiator Temps

AZ-Z71 · July 5, 2003

Installed a 3" body lift back in November. Truck ran great but the temperature outside was below 100. Now here it is summer and the temp crawls up over 100 durning the day. Here is the delima.

The temperature guage flucuates between normal to under boil over while at a drive through. Originally I thought it was the fan clutch but the test for that seem to check out. I took home a/c foam 3"x3" and glued it to the fan shroud to seal the gap tight. Originally 3" of the top of the radiator was still sticking out over the shroud. I removed the weather striping at the top of the shroud, ground off the little lip and attached a piece of metal to cover the 3" over the top of the radiator to hook it back into the shroud. (Got the idea from Mountineer Toms pictures of his lift). This has seemed to work for the most part.

Now the temperature creeps up slower than before but still gets pretty high. I noticed that when you turn the A/C on the engine RPM guage does not go up. I figured it should raise the engine RPM over 500. I changed the IAC valve (at the tune of $100) and that did not work.

Any ideas or is this something that I have to live with since I have a body lift?

One option is to idle up the engine while in line with the accelerator to 1000 rmp and that seems to stabilize the temperature increases.

The other option is maybe to remove the billet grill maybe it has too much restriction.

Radiator fluid appears to still be good looking. 87,000 miles on engine.

mtnvol1 · July 7, 2003

I had a problem similar to this, but without the lift. Here we rarely get to 100, but we have high humidity. My truck was at 100,000 miles. The fluid also checked fine, as well as several other things. The only thing I wound up replacing was the thermostat. You did not say if you checked that, so I believe that would be the next thing to check. Good luck. Let us know what you find.

MountaineerTom · July 7, 2003

I havn't had any problems with mine cooling, even before I did the mod to the fan shroud. I figured it couldn't hurt by doing what I did, plus it cleaned it up a little bit.

Not sure waht else t tell you. Checking the T-Stat, like mentioned already, would be a good idea.

AZ-Z71 · July 7, 2003

I thought about that. I'll go ahead and check it and or change it and let you all know what I find.

Tom,

That little trick with the metal covering the top really makes a big difference out here in Arizona. That was one of the first things I did and it definately makes a difference in regular 100 degree temps.

dcairns · July 7, 2003

are you running the original dexacool stuff? I have heard some people have problems with it doing strange things like turning to gel. Don't know how big a problem it is or if it is simply bad maintainance by the owner, but I will probably change mine more frequently than they recommend.

AZ-Z71 · July 8, 2003

Still have the Dexcool in there. I've been keeping a real close eye on the resivor tank, looking for discoloration or a "mud" look. Hard to see what is going on in the radiator since it is a closed system. So far it still looks good. If I go and check the thermostat then I will be flushing the engine. I have the procudure from the dealer manual on how top do that with regular drinking water. I'm up in the air on using pink or green.

I've seen what this stuff does on a 96 blazer I had. Open the radiator and it looked like someone poured mud in there. The resivor was also muddy looking. At first I thought someone may have over heated and then used some pond water or water from a puddle to fill it in a pinch and it had sediment in it. I flushed it several times and never could get rid of the "mud". Also thought it had something to do with someone adding green coolant in there when there should have been dexcool. Ended up trading that one back to the same dealer that sold it to me.

varmint2506 · July 8, 2003

Generally with a sticky T'stat you will notice the temp. creeping way up then will drop back down fairly quickly. The T'stat will sometimes stick closed which will run the temp up and when it releases the temp will drop due to the surge of cooler water to the engine. If it runs hot constantly, the T'stat may be sticking open which runs the water thru the system to fast and does not give it enough time to cool off in the radiator.

MarkD · July 8, 2003

W/ 87k miles, I would service the cooling system (flush, rinse, replace). Use distilled water (bottled gallons from grocery store) if you go back w/ Dexcool.

I would also step up to a heavy duty clutch fan to pull more air through the radiator/condensor at idle/low speed.

bigtruck21 · July 9, 2003

If it runs hot constantly, the T'stat may be sticking open which runs the water thru the system to fast and does not give it enough time to cool off in the radiator.

If it sticks open, it would be like those failsafe tstats, and would not run hot, but run extra cool almost to the point of making the vehicle add more fuel (choking it). It's not the amount of time spent in a radiator, but the flow through the radiator which determines how cool it will get. More flow=more cool.

varmint2506 · July 9, 2003

It's not the amount of time spent in a radiator, but the flow through the radiator which determines how cool it will get. More flow=more cool.

If you increase the water flow you will have to increase the air flow to achieve proper cooling. If you have a T'stat stuck open or no T'stat at all, the engine will likely overheat when sitting at idle or in slow moving traffic. The higher flow of water with lower air flow will not have time enough to cool properly.

AZ-Z71 · July 9, 2003

I think you are on to something with the thermostat. I noticed that if you idle up the engine while sitting in a line it will cool it down. I'm only talking about 1000 RPMs. Here is what happens. You drive the truck and the temp seems normal. You stop say for like five minutes in line and it will creep up there. You take off again and it drops back down, usually very quickly, like 10 or so degrees almost instantly after driving a couple of minutes. Here is the funny thing now why I think it is the thermostat, the other day I turned the truck off, the temp was correct according to the guage, ran into the house for a couple of seconds came back out and started the truck and the temp shot way up there then back down a couple osf seconds later. It is like the thermostat is stuck open/closed. Usually the temp will be what it was when you shut it off or cooler. That was kind of weird.

Tree_Hugger · July 9, 2003

I think you are on to something with the thermostat. I noticed that if you idle up the engine while sitting in a line it will cool it down. I'm only talking about 1000 RPMs. Here is what happens. You drive the truck and the temp seems normal. You stop say for like five minutes in line and it will creep up there. You take off again and it drops back down, usually very quickly, like 10 or so degrees almost instantly after driving a couple of minutes. Here is the funny thing now why I think it is the thermostat, the other day I turned the truck off, the temp was correct according to the guage, ran into the house for a couple of seconds came back out and started the truck and the temp shot way up there then back down a couple osf seconds later. It is like the thermostat is stuck open/closed. Usually the temp will be what it was when you shut it off or cooler. That was kind of weird.

That actually sounds like your fan clutch......

MikeZ71 · July 9, 2003

AZ- Spend the extra money and install electric fans!

I did it this past weekend but have not been able to fully test it yet in the desert.

During the summer I like to go out to the desert (geocaching and exploring) and I generally don't drive much faster than 20mph due to the bumps. E-fans were the way to go for me. I should have ice cold AC at these slow speeds along with good cooling of the radiator.

Just make sure you have a GOOD ground! I got a hard lesson in that!

knightrider2000 · July 9, 2003

I added 2 14 inch fans behind my radiator that i picked up form my local parts store and keeps the a/c alot colder at idle, check the ac with some ac gauges, and it droped the high side reading 25 pounds, mechanics told me that sould also extend the life of my compressor since it is operating at a lower pressure. Havent really be able to tell much of a difference in the engine cooling gauge stays about 2 notch's shy of 210, but i dont know how accurate it is.. and it hasnt hit 100 here in ARK yet...

Matt G.

AZ-Z71 · July 9, 2003

TreeHugger,

I checked the fan clutch and it is tight. No free spinning and no indication of leaks. I know that it is engaging because you can hear the excess wind noise when reving it up. Initially I thought it was the fan clutch but was later told it was not by the GM parts people. Then I did the test to confirm that and it looked to be fine to me as well.

Knghtrider2000,

2 notches below 210 is where mine always ran. Driving right now it is running there. Stopped for longer than five minutes will drive it over 210.

MikeZ71,

It used to run perferct a year ago in the desert at temps above 100 while in 4-wheel drive low/high. No problems. Even with the a/c on.

OK, so I picked up a new thermostat. What is another $20? Since the coolant has been in there almost 90,000 I guess it would not hurt to drain it now before 150,000 and if I'm going to drain it, I might as well change the thermostat if needed or not so I don't end up changing it a few months down the line if the thermostat is not broken now. (Figuring if it is not broke now, could break later with almost 90,000 on original) I'll run that and see how that works.

Covering the backside of the radiator where the 3 inches stuck above the fan shroud does seem to work to a point. Prior to doing this the temp was running at 210 even. Fitting the fabricated metal shield over the three inches seems to have dropped the temp back down to two notches below 210.