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I have had my 14 Z51 into the dealership now four times (totaling two business weeks) for an overheating issue, that they are unable to replicate (of course) and unable successfully troubleshoot. In short, overheating has happened roughly two dozen times where in the cooling fans will not come on automatically when required normally at 220d under normal driving conditions, usually while sitting at stop lights or in traffic. However, as I soon as I recognize the overheating condition, I turn the car off, immediately restart, fans kick on, temperatures fall right back down to 220d, no further issues.
Dealership has pressure tested system and ran diagnostic's. All system report green. Dealership open trouble call with GM last week, currently with no results.
I searched the forum and did not see any threads of the like. Have any of you experienced this issue, if so what was the resolution?
Did the coolant temp exceed 256 degrees? That is when the overheat warning is displayed.
At what temperature are you turning the car off? How are you determining the fan isn't running? Are you stopping the car and opening the hood to observe.
Low speed cooling fan operation starts at 204 degrees and high speed cooling fan speed starts at 235 degrees. Not sure where you got the 220 number from.
When you get this condition the last thing you want to do is turn off the engine. As soon as you turn off the engine you may reset associated codes. You need to keep it running until the dealership has a chance to see it when it is failing. If there are intermittent failures generating codes that is when they will be able to see them. From the mechanic's standpoint it may be hard to believe you if they can't get it to fail while they have the car.
By the way the fans are usually programmed to turn off once 35 mph is reached as they tend to hinder air flow above that speed.
Bill
Last edited by Bill Dearborn; Nov 17, 2016 at 12:29 PM.
I'm using the 220 number from what my car usually runs on gauge and maintains all the time while driving, to include stop and go. When I have experienced the overheating temps above 255, on two separate occasions I was sitting at a stoplight windows down - no fans on. Turn off, restart, fans kick on temp drops down to 220 gauge temp. Another time I was sitting still in a parking lot, car idling, goes to 255, all is quite under hood, turn off car, restart, cools back down.
Car does not overheat while driving since ambient air is keeping it cool. Unfortunatley every time this has happened I'm 30+ miles from the nearest dealer.
Latest overheat sent to Service Rep so he didn't think I was crazy. Outside temp was 61.
Mine has overheated twice the first time in they just checked the fan connecter and gave it back to me. Always overheated when in traffic going really slow. This time in GM had them take the pump off and inspect it plus change the fluid and replace the thermostat. Both times the fan was not running when it overheated. The difference I noticed now is the fan runs a lot more then it ever did and both the digital and analog gauges are only a few degrees different and before they were 20 degrees apart. Now when I'm in traffic I can hear the fan running at high speed and the gauge will drop from 220 to 210 and when its really hot the fan will run a few after I shut the car off which it never did before
I purchased my 2016 Z06 in July(I live in California and it was hot) and added a LMR thermostat housing with a 160* thermostat. This was working pretty good for about a month. I then added an upgraded radiator since I was going to the track. The car ran way hot at Thunderhill roadcourse but it was about 95* ambient and I did hit the limp mode. I then installed a month later the secondary radiator. While burping the coolant it boiled over at 220* at idle. I was really pissed off, since it was running way hot with the upgrades. Since I had the LMR thermostat housing and I had a 174* thermostat leftover from my Camaro ZL1 I immediately installed that and now the car runs really cool. https://www.corvetteforum.com/forums...post1593324808
The difference I noticed now is the fan runs a lot more then it ever did and both the digital and analog gauges are only a few degrees different and before they were 20 degrees apart.
The digital and analog gauges run off the same serial data signal coming from the ECM. The digital signal is displayed as digital numbers in the Tour Mode next to the speedometer and the analog gauge first converts the digital stream to an analog signal that is displayed using a volt meter calibrated to show temperature. The analog gauge is the least accurate of the two since there are small errors that can occur in the conversion and the meter has an accuracy tolerance as well. The ECM gets the engine temperature from one sensor which is wired directly to the ECM.
The analog and digital gauges can't read significantly different unless a wire is broken, or something is wrong with the digital display or wrong with the digital to analog conversion/meter. None of those types of failures could be corrected by changing the thermostat.
Bill, agreed on the sensors/gauge. If the car is truly overheating and not just having a gauge malfunction, then thermostat is probably stuck closed. This is easy to check and verify.
Another overheating issue
