I got stuck in a pretty major traffic jam today. I didn't get out of 1st gear or over 20 mph for about 1 hour. The water temperature hovered between about 212 and a high of 221. Oil temperature was around 230ish.

If I remember correctly, the first fan turns on around 225 and the 2nd around 235? My Z06 is stock and normally runs right at 194-196. So even though it got to 221, that is still well within the safety margin since the 1st fan wouldn't have kicked on yet?

Also, at what temperature do you need to pull over and shut it down?

 

You need to go see a tuner and get your fans re-programmed. Your temps are acceptable, but you better make sure you have a proper mix of Dexcool and distilled water and a good cap to keep your boiling point elevated. You may also want to remove the cap off the radiator and condenser and blow the garbage out. You'll be surprised at how much comes out. I programmed my fans to come on at 180 and 190 with a 160° thermostat. Also check the front of the condenser and make sure you don't have any obstructions such as a grocery store baggy. Make sure you also still have the air dam under the car. It is a critical component to forcing air through the radiator.

 

Yep, I've done all of the above. I just had the cooling system flushed about a month ago as part of routine maintenance. I also check for and clean out any debris every week when I'm cleaning my car. The airdam is still in place and in good condition.

The temperature is normally very cool and constant at 194. It's just this horrible traffic jam today where the temperature has gone higher. I literally went over 1 hour without moving more than 1.5 car lengths at a time. Thankfully I only had to go 12 miles because the backup was a total of 35 miles due to multiple accidents.

 

Those temperatures are not out of the ordinary for heavy traffic driving on a hot day.

Data I had saved about the 2-stage fan system:

T-stat = 195 F, opens fully at 202 F
Stage 1 Fan = on @ 229 F, off @ 222 F
Stage 2 Fan = on @ 239 F, off @ 230 F

I checked the stage 1 fan on/off running against my DIC coolant temps, and found it to be within a degree or two of the above data.

It certainly can't hurt to clean out the radiator.

 

I run 225-234 in stop and go traffic and that is normal. On the highway about 192 and this is with stock thermo and fan temps.

 

I don't like the idea of having a shop flush a cooling system because they don't ever use distilled water. Not using distilled water will leave mineral deposits all over everything internally and prevent thermal transfer. If it were my car, I would drain out as much as possible and refill with distilled water. 70% water and 30% is good for down here in the south, but you may need a higher amount of Dex due to being up in the nosebleed section. Less coolant= better thermal transfer. If my car hit 235-240, I'd shut it down. 230, I'd get nervous. Get your fans reprogrammed at the least.

 

The ONLY time the coolant temp will stay at a constant 194 F is when your are cruising down the road at light & constant throttle with good air flow through the radiator.

Every car will run hotter when in stop-n-go traffic, or just putting along at 10 mph. That is why they put fans on the radiator.

I would say there is nothing wrong with your car ... mine runs about the same in heavy stop and go traffic like you described.

 

Less coolant also means lower boiling point. It's pretty much been a 50/50 mix that gives you the best protection and boiling point temp.

 

Those figures for fan cut in are good. You'll get a coolant over temperature at 256 degrees which is about the time that I'd pull over.

From the figures you saw the fans were coping just fine. I'd see those temps quite often in Vegas

 

When I changed my coolant, I didn't flush the system as it was clean as day 1 inside the engine. I did remove one of the hoses off the water pump outlet and was able to blow almost all the coolant out of the block. The re-filled with premixed 50/50 of distilled water and Dex-Cool. Almost took the advertised system coolant capacity, so I was comfortable I got most of the coolant out of the block.

Another thing about flushing is that pure water is left in the block. It's a bigger challenge to know exactly how much coolant to add to end up with a 50/50 mix.

 

Yep, if it's in fact a 12 quart system, you had better be able to get 6 quarts of Dex in there to get your 50/50

 

Everyone, please get out your Owner's Manual .......

Turn to the Index in the back and look up ENGINE ..... and look down until you see "Overheated Engine Protection Operatng Mode" .... now turn to that page and READ what your Owner's Manual has to say about an overheated engine.

It says you can drive up to 50 miles with an overheated engine. This feature was first developed by Cadillac back in the 1980s. One of the car magazines didn't believe that this would work, so they got a Cadillac, drained ALL of the coolant from the engine, and then drove it around. If I remember correctly they ended up driving it 500 miles before they tore the engine down. To their amazement, the engine was unharmed.

This feature works by injecting fuel at the time it would normally be injected into the engine, but the spark only ignites the fuel every other fuel cycle. The unfired cycle is a "cooling" cycle for the cylinder. Notice the recommendation to change the engine oil ... this is because the oil has been exposed to higher temperatures than normal (though a synthetic should not be a problem with this), but also because the oil may have been contaminated by gasoline washing down the cylinder walls.

Your Corvette engine can live and function at much higher temperatures than engines could 50 years ago. You're not driving a BelAir with a 1960's small block, this is a modern LSx engine designed to normally run at around 200 to 220 degrees ..... engine overheat protection doesn't kick in until 265 degrees .... as Bugs Bunny would say .... UNLAX.

 

I'm going to have my fan turn on reprogrammed but I've always used the ol' "turn on the AC" trick which forces the fans on full time.

Even in 100+ ambient temps and stop-and-go traffic, my coolant hovers around 215 and oil temp around 225.

 

I'd consistently see coolant and oil temps of around 230 in LA traffic jams... it cools down pretty quickly once you get out of first gear and get some air flowing. Nothing to worry about.

 

If you don't get the temps in the red, then it is still within normal operating temps.
Modern cars are designed to run hotter because it burns more of the fuel and decreases emissions. Don't worry about seeing temps like you did, that is normal.

 

This is true. The 50/50 mix will raise the boiling point to 265 F with a 15 psi cap. Just using pure water with a 15 psi cap the boiling point is 250 F. With a 30% coolant and 70% water the boiling and a 15 psi cap is 260 F.

Good luck

 

I thought it would be worse than 260 F with a 30/70 mix, so it's not far off from a 50/50 mix. I understand that if you were to go buy a new coolant tank pressure cap from the dealer that they are all 18 psi now. The OEM pressure cap was 15 psi on my '02 Zee.

 

You don't seem to have a problem. As far as getting too hot you aren't even close. Besides, the PCM will let you know if the engine is too hot by going into limp home mode. Your oil temp is fine also. Distilled water isn't necessary either as GM says drinkable tap water is sufficient. Even with a Ron Davis Racing Radiator and an engine oil cooler I see coolant temps of 230 degrees on the track and oil temps in the 265 range. This is when running at WOT for 20 or 30 minutes in 80 to 90 degree weather.

Bill

 

These 4 steps will all contribute to help lower coolant temps

1. Reprogram fan settings to come on earlier
2, Install 160 or 180 degree thermostat
3. Throw in a bottle of Red Line Water Wetter.
4. Flush radiator and condenser fins with water or compressed air

 

Two summers ago, I had a problem with my car running too hot with the A/C on. Coolant temp (and oil temp) would climb to 240+ degrees unless I got on the interstate and cruised, and then they would only stop climbing, not go down, unless the A/C was shut off. I read somewhere that the radiator can become clogged with rocks and sticks and debris (actually through the radiator and condensor) so I pulled the radiator and used water and air to clean it. It took about 45 minutes to get the radiator and condensor clean and it made a world of difference. I can run the A/C in 90 degree heat and my coolant temps dont go above 210 degrees while idleing and sitting still (160 stat).