Corvette Performance - 98 C5 Cooling Issues

So before I unload all my .223 rounds into this car I thought I'd ask your advice.

I have a 1998 Chevrolet Corvette LS1 auto. Only mods are CAI and ZO6 exhaust. I live in deep south Texas where temperatures are currently reaching anywhere from 97-104 degrees.

With that said, this damn car keeps reaching temperatures over 220 degrees at a light with A/C on and keeps steady at 218 degrees cruising at about 65mph. Yesterday I achieved 232 degrees at idle, which doesn't seem too safe. It has no problem warming up from a cold start. In the evenings when the car hasn't been on all day, temperatures will not drop below 200 degrees at any mph after warming up. At idle the car tends to warm up quick and sometimes will drop a couple degrees if i switch the A/C off and also when i get moving at about 45mph. So this is what I've done in the past.

1. I've checked the radiator for any bags, cardboard, leaves, shirts, underwear or anything else that might get sucked up.

2. I've gone at the radiator with a pressure washer several times to clean it out.

3. I flushed the system twice and added new fluids twice.

4. I installed a 160 thermo and had a buddy set the fans to compensate for the 160 thermo.

5. I checked to see that the fans work and know they do since they're always on.

My next step is changing the Water pump and after that the radiator. What am I missing? What should I try before taking those step? Any help is appreciated.

What else could it be?

I know you have cleaned the radiator but it might be worth pulling it completely to clean. I helped a friend with a very low mileage 04 install a cam and when the radiator was out he figured he would give it a quick clean. Well you should see what was in the fins of that radiator including dirt and sand some of which we couldn't get out. If you have the fans settings set lower and a lower thermostat and still seeing high temps, it may indicate the radiator is just not exchanging the heat properly.

Also, I am sure you know, but look between the radiator and the condenser.

Could also be solidification inside the radiator. The veins do develop calcium particularly if you use water other than distilled to fill. And too if it's the original radiator it's getting pretty old and likely needing a disassembly and rodding out.

I know you have cleaned the radiator but it might be worth pulling it completely to clean. I helped a friend with a very low mileage 04 install a cam and when the radiator was out he figured he would give it a quick clean. Well you should see what was in the fins of that radiator including dirt and sand some of which we couldn't get out. If you have the fans settings set lower and a lower thermostat and still seeing high temps, it may indicate the radiator is just not exchanging the heat properly.

Also, I am sure you know, but look between the radiator and the condenser.

This area will suck up anything on the road. I had coffee cups, hay, news paper and such stuck in there.

Its just weird how it warms up so quick. Have had 2 f bodies in the past and never had these issues.

I clean out my radiator all the time. I pulled out my stock radiator to install a DeWitts radiator and this is what came out of my stock one after many cleanings.
http://farm6.staticflickr.com/5192/7434487248_d5b52b8e5b.jpg

DeWitts radiator.
http://farm6.staticflickr.com/5469/7434468028_ee0d93361c.jpg

Steve A.

^ Jesus christ dude! Honestly your temps aren't EXTREMELY high. I wouldn't have went with that 160 man, thats too cold and your going to have condensation inside. I think if your tuner would just have the fans activate sooner you would be fine. Car operating at around 210* is optimal.

So running at 230-235 is OK?

My biggest question is why even with the 160 thermo and fans always on do I still see temps of over 225?

i would say that something is amiss with your radiator. my 04 with 408, a4, electric waterpump, 180 thermostat rarely sees 200 unless i beat on it, hard. thats in south mississippi heat. stock radiator(cleaned out more than once).
dave

I would say something is definately off and I suspect the inside of the radiator. I live in Corpus Christi so it's just as hot here and my corvette never goes above 200. It used to run over 200 degrees also, but when I pulled the radiator for a cam swap last year I cleaned and flushed everything real good, installed a 160 thermostat, and now operating temps are always 185-200. Best of luck!

Could possibly be a faulty sensor as well.

For got to fill you guys in but I think it might be the thermostat. I let the car run for a while and it got up to 205 quick. My friend asked me to pop the Hood to see if the fan were turning on. You could obviously here them but stuck his hand behind the fan he noticed it was nothing but cool air but my temps were still high. I revved it up to 2k and the temp started to drop. Also the hose past the termo was cool to touch. I'm just gonna swap it for another 180 and see what happens.

98 C5 with the SAME THING.... I have less than 95k, so i wanted to rule out a head gasket. Even had it tuned 'factory' on HP Tuner. Anyone wanna buy a used Vette?!


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Im also in Texas and my 02 Z06 would get hot too. Winter Fall and Spring im always 172-190 but at certain times in summer it gets hot. Standing still with ac on when its 100+ out aint easy to keep cool. Highest I saw was 235, but 210-220 is notmal down south. Mine would always cool back down once I got some air flow.

This is a common, and often "heated"(pun intended) discussion on Corvetteforum. I, personally have seen up to 238ish in my Z. BUT... It was ONLY when the AC was OFF and at idle in traffic plus 100* weather. I wouldnt call it "normal" to run this warm by typical automotive standards;however, I would say it seems to be "acceptable" by C5 standards. I cant recall the exact info, but something regarding the HI fans, or 2nd fan, comes on when the AC is engaged. Otherwise, temps have to rise pretty high for it to kick on and by then it takes allot to cool it down. I just leave my AC on. No problems at all. Just for the record, my previous C5 was the exact same way. So DONT go throwin .223 lead at the car. BUT, if youd like to simply get rid of some .223, hit me up! ;)

1998 C5 black auto 60k $15k