I've had this problem since I bought the car, but have just recently descided to adress the situation. When I first got the car I went ahead and got a hypertech chip, t-stat, and fan switch (didn't know any better about the chip at the time). The t-stat is 160* and the fan switch is 176* but yet the car exceeds 220* quite often. I figured the radiator was to blame, but it's a single core and flows like a champ. I replaced the hoses and waterpump also. So I got frustrated and left it alone for a long while....now the car is back to being a daily driver and i don't like it running as hot as it has been. Does anyone have any suggestions on what to try to make it run cooler??

This is what I've done so far:
Flushed the entire cooling system
Taken the t-stat out
Added about a 75% Dexcool mixture
And I've also tried running the fan fulltime

 

Did you try taking the t-stat out, after all those other
changes?
Is there a chance of an air pocket, trapped in the block?
When the fan is on, is there healthy flow of air?
(note that 'taking the t-stat out', is my knee-jerk suggestion
for diagnosing overheating problems. Try it again)
Do you sense that there is enough water flow into the radiator?

 

This worries me. by Dexcool you mean the orange stuff?? if so, it is not compatable with the 'Green Stuff' there is a not so good chemical reaction between the two. If you did mix them, do a full flush on the cooling system.

I would not try with the t-stat out, you need the small opening for everything to work right. you best bet would be a good 160 or 180* stat.

are you fans comming on at the temp they are supposed to? does the car heat up on the freeway also? do you have the black air dam on the bottom of the car?

 

Do you have the air damn under the nose of the car to push the air up to the radiator? A friend was running hot and that was his problem.

 

Check your air damn, type of coolant (use the green stuff), and put the t-stat back in. Without it the water doesn't have enough time to cool in the radiator before it is pushed back into your motor. Your coolant has to sit in the radiator for a bit for it to work correctly. If that doesn't work than i would put the stock fan switch back in along with nothing cooler than a 180* stat. There may be a mix match of chip/t-stat/fan switch going on that is preventing anything from hapening.

 

Well, I did a full flush already and then went back with the Dexcool. The air dam is intact under the nose, someone had already suggested it. And I just recently took the t-stat out as a shot in the dark.

The fan comes on when it's suspose to and pulls plenty air. The flow is great...if i revv it up with the cap off it'll shoot out of the radiator. I've even taken the hose off the radiator and ran it with free flow and it moved PLENTY water.

I'm at a loss here...it's friggin annoying.

Edt: Oh, and when i bought the chip/t-stat/fan switch... it was what hypertech reccomended that i use so i just went ahead with it. they claimed that it HAD to run cooler to prevent detonation...which i now know is

 

So did you put that Tstat back in? Did you put the cap back on so that the system could pressurize? If not I would suspect those as being your problems. Also, you could have a bad sending unit which is making your gage read high. Have a shop, or go buy, use an infared temp reading gun and point it at the hose by the t-stat. It should be in the 180 to 200 range regurdless of what the gage says.

 

Yeah, i tried it both ways...it's acts almost the exact same with and without the t-stat. I know the temp sending unit is functioning becuase when it gets to that "too hot" point, it will start to boil over into the overflow resivior.

I've been REALLY leaning towards bad hoses that are collapsing becuase as long as i don't exceed around 55mph....i'm fine...i can even run the A/C. But anything after roughly 50-55mph it'll start to heat up quickly....hell, it could be the pump too. Maybe i should just get a decent high-flow pump.

 

I would check your water pump like you said. Keep the t-stat in and if you can go back to the stock fan switch and chip and see what that does.

 

Well, it did the same thing before the chip/switch/t-stat change. it actually runs somewhat cooler compared to before. I thought about trying the stock chip, but it got water on it and it is ruined. I really need to go see craig and let him tune the **** out of it for me.

 

Try replacing all your hoses and then buy a new radiator cap. Maybe the cap is not holding pressure.

 

Why are you using Dexcool?
That choice, seems to be controversial.

 

I also have cooling problems. I have a Jet cooling switch, Hypertech 160* t-stat, Moroso 19 Lb raditor cap, 20% Zerex G5 antifreeze/coolent, 80% Disiteled water and a can of Pro Blend 40 Below water wetter. The car still hits between 200 & 220. Its been a ever going battle to keep it cool.

My next plan of attack is to install GoodYear Blue Hi-Miller hoses, a TPI duel fan, Griffen raditor and a 3" Cowl hood. I think this will finily cool things down. I've saw IAT sensor temps of 235* before. The factory hoods really seal up & retain heat in the engine bay on third gens, this is'nt the first one I've had this problem with. I think after you start making some decent power with these cars theres just not enough air flow to cool them off?

 

so you're water pump is new? If not, then I'd start there.

 

Chevypower,

If I am not mistaken, 200 - 220 would be considered normal operating temperature.

 

Just a thought but maybe it's the timing. I would guess you've checked that allready??

 

EEEEk I shudder when mine comes close to 200, I like to keep it at 160....