Can anyone share what the spec might be (if there is a specific one) at which the coolant temperature for a 2012 GS (LS3) 6MT is considered to be in the overheated range??? I am likely just missing it but I can't find a specific temperature spec at which to consider the car to be overheated...

thanks... bob...

 

I have a stock '08 (LS3) with an automatic.

As far as coolant temps go 200-220 is completely normal. I think that's a bit high, but it is normal.

The thermostat starts to open at 188, and is fully open at 206
Fan starts when:
Engine coolant hits 204 (Lo speed)
235 (Hi speed)

or

Engine oil temp hits 302 (Hi speed)

or

Tranny temp hits 270 (Hi speed)

When engine is turned off, fan will run for a max of 2 minutes if engine coolant is 235 or high pressure in A/C.

I would guess these numbers would apply to a 2012 GS.


Hope this helps.

M....

 

It is overheated if the temp goes over 256 degrees. Here is the description of the C6 cooling system.

Cooling Fan Control - Variable Speed Single Fan System
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal.

Cooling fan speed is effected by many different conditions and can be adjusted from 10 percent to 90 percent duty cycle (PWM), 90 percent is considered high speed fan. When multiple cooling fan speed requests are received the ECM uses the highest cooling fan speed of all the requests. The ECM commands the cooling fan ON under the following conditions:

• Cooling fan duty cycle starts when engine coolant temperature reaches approximately 95°C (204°F) and reaches high speed at temperatures above 113°C (235°F).

• Cooling fan duty cycle starts when A/C pressure reaches approximately 1100 kPa (160 psi) and reaches high speed at A/C pressures above 2480 kPa (360 psi).

• At engine oil temperatures above approximately 150°C (302°F) the cooling fan duty cycle will be commanded to high speed.

• At transmission oil temperatures above approximately 132°C (270°F) the cooling fan duty cycle will be commanded to high speed.

• After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 113°C (235°F) or the A/C pressure is greater than 1720 kPa (249 psi) the cooling fan duty cycle is set to 50 percent, low speed. If the coolant temperature drops below 110°C (230°F) and the A/C pressure drops below 1660 kPa (241 psi) the fan will shut OFF. The fans will automatically shut OFF after 2 min. regardless of coolant temperature.

Low Coolant Message
The engine cooling system utilizes an algorithm based low coolant level system which eliminates the need for the coolant level sensor previously positioned inside the surge tank. The algorithm measures the difference in engine coolant temperature readings over time as a function of engine speed, to determine if the cooling system has a low coolant condition. After vehicle start up, the engine control module (ECM) sends an engine RPM and engine coolant temperature message through the body control module (BCM) to the HVAC control module. The HVAC control module uses engine coolant temperature and engine RPM to determine if an increase in engine coolant temperature is due to a low coolant level condition. This system is capable of losing 2 full liters of coolant before triggering the Low Coolant indicator. Because the surge tank holds approximately 0.8 liters when filled to the proper level, its possible that the Low Coolant indicator will not be triggered, even though the surge tank is completely dry.

Engine Coolant Indicator(s)
COOLANT OVER TEMP
The IPC illuminates the COOLANT OVER TEMP indicator in the message center when the following occurs:

• The PCM detects that the engine coolant temperature exceeds 124°C (256°F). The IPC receives a class 2 message from the PCM indicating the high coolant temperature.

• The IPC will also illuminate the CHECK GAGES indicator and a chime sounds when this condition exists.


Bill

 

Good stuff, Bill

 

thanks guys... I appreciate the help... good info... Need to absorb it now... bob...

 

To put those numbers in a more "useable" perspective:

Cruising the highway after 15 minutes, coolant will normally be ~190, controlled by the thermostat.

As you stop or get into traffic; coolant will start to climb, that's normal and anything below 235 is still normal.

If coolant gets above 235, it's time to start paying attention. Redline is 255, I've never come close to that even stuck in traffic on a hot day. I don't even remember seeing above 235 in traffic, but my local temps don't go over 100'; people in Phoenix might see something warmer than I.

The highest temp I've seen on our A6 transmision, stuck in traffic on that hot day, was 219. Running a fast twisty road with lots of power and paddle shifting, can get it to 230 or even higher. Caution starts at 230, redline is 270.

Any oil temp below 260' will not harm the engine, I consider 302' oil the redline because the radiator fan goes to high at that temp.

 

Also, fan is commanded on when the A/C is in use, regardless (virtually) of water temp, so don't be surprised to hear the fan in this case.

 

It's about 90 out there today and my coolant is hovering in the 180's.Short highway 1 exit trip.Is that normal or on the low side??I was wondering if this thing might have a 160 stat in it.

 

Most of the time my temp runs 192 cruising on the highway. Every once in a while, I will notice it will drop to 187, but return to 192 after a short while.

 

Next time just look at the gauges; they have their respective redlines clearly marked (coolant shows 260º on my '12 GS) . And contrary to most cars on the road, where the coolant temperature gauge is BUFFERED, meaning the needle doesn't move from 190º to 235º, on the Vette is shows exactly what the temperature is, so you can watch it move as driving conditions change. The most important number from all the ones thrown above is the 235º one. If everything is fine with your car, it shouldn't go above that. Unfortunately, freaking cheap GM had to eliminate the low coolant sensor on the reservoir, so now if you get the stupid message, it means your reservoir is empty plus you're a QT+ low inside the system. Not good at all. Therefore it pays to check your coolant reservoir often. If you start losing coolant after reservoir has stabilized (sometimes new cars are not completely purged, and takes a few weeks to stabilize), it means you have a leak somewhere. You don't want to find out by your dash light, because it's too late. Good luck.

 

fyi on 2005 192

 

192 is normal operating temp on the highway, definitely not overheated.

As previously stated, above 235 is getting warm and 255 is redline.

 

I gone to 226 to 235 once idling in traffic jam.

 

160 degree t-stat and a chuck cow tune and it stays at 178 degrees yesterday at 100% outside

 

So you have a stock t-stat or a 160 in yours?Mine does the same thing I think.

 

Stuck in heavy traffic in 90plus degree heat I see 207 with ac on. That was the hottest in 2 hours. To cool a thermostat promotes more rapid ring/cylinder wear. Not the place or time to get into how/why but I've read several articles by engine/engineers about cool thermostats and the affects they have. Good and bad and too cool increases ring/cylinder wear.

 

Is there a way to program the fan to start off on high speed and just eliminate the low speed? And would that be to much to long in high speed?

 

A diablo tuner can do that for you.Or any good tuner as well.Fans are set according to factory specs though for the best cooling when needed i guess.

 

Probably a good guess
I have found with out exception they know way more than anyone else- was a stupid question on my part really.

 

Good info.

Keep 'em cool. Drive 'em today if you can.