so my first vette, and I need to know if I am reading into my company temps or if there is really an issue here. I know they like to run hotter.

Base c6 auto. Had the engine rebuilt earlier this year, new heads, cam intake, shorty headers stock cats, all engine accessories, belts, hoses,TB, intake, coils, fuel injectors were all new. Did a dewitts fan with internal trans cooler, and an external oil cooler.

got the car back during the winter and didn’t notice anything temp wise. When driving the temps are ok hovering around 195-205. Come summer (Houston area) temps would climb up to 220 is city traffic. I got caught on the highway at an accident where no one was moving and after 10 minutes the coolant temp was over 245. The heat index was 103 on this day Luckily traffic started moving. I was able to replicate this in my driveway to verify. Replaced the thermostat 160, and it got better, after 10 minutes at idle it got up to 227 but the heat index was only 93. After 20 minutes, it was pushing 237. Had a combustion test done, checked for leaks, and no issues there. So in my mind the only thing left is the water pump, correct?

and yes the condenser and new radiator fins were cleaned out with air and water for any debris.

 

100 degrees out, stopped, with the A/C blowing -- it doesn't sound like anything's wrong. Thermostat will only prevent your car warming up.

 

thanks. Just wanted input as I really do t want to go further down this rabbit hole if I don’t have to.

 

Water pump is good, no reason to replace it and the thermostat is working as it should, doesn't matter the number (160 or 190) because open is open.

 

Did you do the Dewitts dual fan conversion on this? Also check you fan connector to see if it has melted along with pull the fuse in the fuse box to make sure that has not melted int he fuse box itself. What can happen is it gets hot is melts and it can either partial disrupt or total cut off the electricity with the melted plastic. Turn car off plastic cools off and it starts again when you run it.

 

Where we feel add'l warmth from humidity, mechanical devices are unaffected by this factor.

When was the last time the coolant was replaced?

When sitting in traffic and the temp skyrockets, you might turn "ON" your A/C. This commands the fan to turn at 100%.

Also, if you've had your car tuned, you can change the parameters for fan duty cycle, inside the tuning tables.

Check your fan blades for melting or missing blades.

 

all checked all good. No issues with the Dewitt duel fan assembly.

 

fans checked. All good. Good to know about the humidity thing and the coolant was less than 3k miles on it before it was changed out again earlier this week. Will check on The tune and fan speeds. Thanks.

 

Strongly disagree. 245 is not normal under any circumstances for a non-boosted engine in Houston, even with 103 heat index stuck in traffic.

To the OP, are you running a Dewitts radiator or just their fan setup? I'm guessing the radiator but want to be sure. How much have you driven the car since the rebuild? Any change the coolant system wasn't bled properly?

 

running both the rad and the dual fan setup. The rad has the trans cooler and I am running an external oil cooler as well. The car has under 2k miles since the rebuild and we have the fans coming on as soon as the car starts and at max speed. I took it out yesterday and drove it in a mix of traffic and highway since the temp was in the mid 90’s. Hottest it got was 230. At highway over 60 she cooled down to under 200. Stop and go would steadily climb up slowly and maxed out a few times at 228/230. This was after the 160 therm was replaced and system was bled out. Going to take it out again the afternoon as the ambient temp is supposed to be 95+.

 

Agreed. Even here in ATX, I hover around 210-220 in traffic. I think that the only time I saw 240+ was when my water pump failed and my rad had a leak. In fact, back in July, doing some troubleshooting and had the car running in the drive way for about 10 mins. No issues with temp.
OP - coolant level good? Did they actually use coolant and not straight water? Could be an air bubble somewhere as well. Going to PCMusicGuy's last comment about the system not being bled properly, this would be a good place to start.

 

dexcool is what was used. Depending on readings today I will give burping another shot.

 

Have you confirmed the coolant temp sensor is functioning correctly? Or just try replacing it.

Is all of the OEM radiator shrouding, air dam, etc. in place?

 

Update. So I have replaced the 160 therm again, radiator cap, new coolant again, no leaks visible. Therm is opening as the hose gets hot really quick about 170. Car will run cooler going 40 or more, low 200’s. If I am in stop and go traffic it will fluctuate between 115 and 230. Sat in the driveway after driving it for 2 hours with the above readings and it got up to 239. Turn of AC, turned on heat to highest setting and blower fan lowest and it only came down to 237. Turned ac back in and now it only blows out hot air. Ac is gone. Hoping it is just related to the under hood heat. Going to let it rest for the night and see what it does tomorrow. To not the coolant, not the cap, not the therm, not the head gasket (passed combustion and pressure test).

 

Last year I experienced temps not decreasing while idling. Slightly brought up RPMs and temp drop quickly. Flushed the system and swapped T-stat but no change. Ended up swapping water pump and problem resolved. Had cars in the past where impeller started to slip on the shaft but wasn't the case this time. No idea why it wasn't flowing at idle.

 

well, it is rather going to be the water pump or simply that the Dewitt fans aren’t pulling sufficient airflow through the front at idle. Might as well handle both at once. Car will be driven back and forth from Houston to Phoenix so cooling is essential.

 

The fact that you are cooling down when moving and when you are slow are stopped the temps go up means either not enough air moving over the radiator when slow or stopped or not enough coolant flowing.

And if you have checked that the fans are indeed running and everything else is good, it is the water pump.

 

Photo or raditor install, or better yet, make dam sure that flaps on the fan mount, have the flaps opening on the down side.

If you installed the fan assembly up side down, with the flaps swing open from the opening side upwards, then air is not being pulled through raditor when car is stopped, but just being pulled through the flaps that have swung open isntead.

Hence stopped and fan is running, fan should be sucking the flaps closed, so fans are pulling air through the radidtor,


If such is correct, and using oem raditor that has miles on it and the condensor in front of it with miles on it as well, may be time to break out the hose wands to reverse clean them.

Last one, get under the car, and if you have additional coolers in front of the condenser, make dam sure you have at least a 1" gap between then bottom of the condensor and the cooler, so when car is at stop light stopped, the air going to the conndensor and raditor can pull cool air from the bottom, isntead of just through the cooler in front of them. Hence see this problem all the time with intercoolers mounted too close to condensor with now gaps between there bottoms, and the only air though the condenser and radiador, is only the not air through the Hot intercooler itself.

The bigger the gap,

The more cooler air that is drawn through the condenser and radiator when car is stopped.
And yes, air filter system like the vararam , block this cooler air flow as well through the condener and radiator, and causes the motor to run hotter as well.

 

I'm old school here, so take this as a suggestion of a test in an around town setting (meaning low speed) where you would overheat. Get yourself a piece of about 2" thick Styrofoam, about 4" wide and 12" long. When you're in the stop-and-go situation with the engine temp climbing on you, pull over, pop the hood and slip the Styrofoam between the hood and wipers to allow the hot area to vent over the windshield. If that helps, then you're having a heat lock situation under the hood. If that works, then you need to figure out how to vent the under hood area of excess heat. Have a friend that had a restomod 54 Vette, he did that as one step in figuring out what could be done to fix his overheating problem. In my youth, we removed the hoods on a couple of cars due to overheating, so it's been around a long time.
Good luck.