btorlv

I was driving around for 10 min. slowly looking for a parking place. The alarm sounded, I pulled over and parked immediately. The temp went up to 250. I opened the hood, car belched out about 2 cups of coolant. Waited about 10 min., restarted the car, the fan immediately came on and after I shut the car off, the fan stayed on for about 10-15 min. I came back to the car about 2 hrs. later opened the cap and took about 8 oz. of distilled water to fill back up. We drove the car about 50 miles home and the temp stayed about 192-195. This is the 2nd time this has happened to me. The 1st time I had to have it towed to the dealer. They kept it for 2 days and they couldn't find anything wrong with it. The dealer thought the fan connector was probably loose. I see that a couple of you have had the water pump replaced. I am not sure if the fan was running when I was looking for a parking space. Not sure if this is a fan issue or a water pump issue. We were planning on taking it on a 1000 mile trip to Monterey next week, but not sure if I trust it at this point. Will take it to the dealer and see if they can find the problem.

Vetteman Jack

Good luck - hope the dealer can figure out what is going on with your car.

C8-Vette

Sometimes air can be trapped in the system and cause overheating at slow speeds. Try removing the coolant cap (only when cold)warm up the engine for 10 minutes, and with the cap off rev to 2000 rpm for 2 or 3 minutes. Have someone observe the coolant bottle for air bubbles.
Hopefully this may solve the problem.

Crossed Flags Fan

Things to consider....
Was the AC on at the time, and if so, was the radiator fan working at the same time? The radiator fan should be on whenever the AC is on. If it isn't there note this when you bring the car back.
Did this happen the second time under the same conditions, that is, were you driving slowly with the AC on?
Make sure you have the dealer test the car under the same conditions - driving slowly and as close to the same outside temp.
Now that youve added water you should make sure that the coolant mix is at least 50/50.
What year, model do you have?

PUGPROUD

Make sure nothing blocking air inflow and think about removing license plate...both short term measures till you find root cause. Also think about checking function and perhaps changing thermostat to lower temperature setting.

btorlv

Both times were the same conditions, 75/80 F with air on and driving 10 15 mph. The first dealer said it might of been the fan connecter after they called tech support. the vet is a base coupe with the Zf1 kit. this time I hope they change the fan out and I'M seeing some members have had the water pump replaced.

Bradysdad

Good advice on checking for airflow blockage. Potentially picked up something like a plastic bag which attached itself to the radiator. But the other suggestions....on a new $60K+ car? You shouldn't have to worry about removing the plate or changing the thermostat. If there is a design issue, GM needs to take care of it, not the consumer.

Good luck with resolution and please keep us posted.

Larry/car

I think you have a thermostat that occasionally hangs up. I would have dealer replace it with a like unit of same temperature range. I had a car act up just as you are describing and a new thermostat solved the problem. (192/195 degrees you observed later, seems low. My car consistently indicates 220 +/- a degree or two with a matching oil temperature)

btorlv

Thanks, my biggest worry is I will get the car back with a note stating unable to duplicate customer's concern. Took me 10 years to pull the trigger on a Vette. And let me tell you these baby's don't go on a flat bed all that easy the last time we had to use 2x4s to clear the front end and mine is stock height.

Larry/car

Intermittent problems are a bitch to solve. Technicians tend to replace suspected components until problem goes away. My overheating issue was on a Chrysler a few years back. Like I mentioned previously replacing the thermostat cured the problem. Thermostats normally are designed to fail open, evidently the valve can bind and spring tension can't over come the resistance. When the engine cools off the demension of components change freeing the stuck valve. The valve now operates normally until it binds again. Anyway that is what I would replace (fairly easy), hopefully after replacement problem never returns.

Red08

btorlv

Last time it over heated the Dealer refused to replace the Thermostat said GM did not approve it after talking with tech support.

Larry/car

I think I would pay the replacement myself, for now. Document with the dealer and if it doesn't over heat within an agreed period of time, warranty!!!! Other than an air bubble (unlikely though the C4, if serviced incorrectly occurred but wouldn't be intermittent). What else could it be? Fans are running, water pump doesn't pump intermittently (pump vanes are firmly attached to drive shaft) pumps water or it doesn't, radiator not likely (air flow through core problem? baffle seals not correctly installed). The cooling system is basically open circulation with the thermostat controlling the flow. No or reduced flow the engine will overheat. Just what does Tech Support think it is? Inquiring minds need to know!

Steve_R

A lower temp t-stat won't make it run any cooler once it's up to operating temp.

OP, let us know the outcome.

BJ67

As long as the car is moving over 35mph, the engine temp will be consistently cooler than with the factory stat.

40flier

Start the file for lemon law claim.

btorlv

Dealer cant duplicate concern. The Concern is both times the car overheated the fan was not running. This time the fan only came on after I restarted the the car for 15 sec and when I shut it down the fan ran for 10 min. Cant understand why they wont replace fan or ecm that controls the fan. Don't want to get stranded or have motor burn up. it is no fun to drive the car at this point always watching the temp gauge and trying to get over to the shoulder on a busy L.A. freeway.

Dif

IMO, your dealer doesn't sound very cooperative and you need to go to a different Dealer to start with.
Brand new Thermostats have been know to fail.
Just a suggestion, but if your fans are not running when they should, and the Dealer will not do anything, disconnect your battery for 5 minutes and hook it back up.
Then keep an eye on how the fans run taking note if they run differently or not.
Good Luck whatever you decide

ferd1971

I just drove my C7 nearly 200 miles last weekend and my temp stayed at 220 degrees without any problems.

btorlv

There taking off water pump to inspect it, at least that's a start. Fans are running well at this point. that's what tech support told them to do. At least there looking into it and not just handing me back the car.