Momentary overheat
Thread Starter
Drifting
Joined: Oct 2014
Posts: 1,733
Likes: 403
From: Atlanta, GA
Momentary overheat
2015 Z51 M7. 27,000 miles
Sunny day. Mid 70s. I wasn't driving hard. I was on a phone call and needed to pull over and stop to write some info down. Sat in a shaded area for maybe 5 minutes at idle. Noticed the AC stopped blowing cold air. Then I noticed the engine temp (permanent needle gauge) was at 260. My car NEVER runs hot. Usually steady at 200. Maybe 210 while in stop n go in mid summer in epic traffic in Atlanta.
When I started driving again, engine temp creeped back down and the AC resumed normal operation.
So, last two days I've been watching the engine temp. Now it's been hovering at 205-210. I always watched it before and I KNOW it's always been steady at 200 prior to the temp spike.
Any ideas?
I'll probably take it by Chevy soon when I can find time.
Sunny day. Mid 70s. I wasn't driving hard. I was on a phone call and needed to pull over and stop to write some info down. Sat in a shaded area for maybe 5 minutes at idle. Noticed the AC stopped blowing cold air. Then I noticed the engine temp (permanent needle gauge) was at 260. My car NEVER runs hot. Usually steady at 200. Maybe 210 while in stop n go in mid summer in epic traffic in Atlanta.
When I started driving again, engine temp creeped back down and the AC resumed normal operation.
So, last two days I've been watching the engine temp. Now it's been hovering at 205-210. I always watched it before and I KNOW it's always been steady at 200 prior to the temp spike.
Any ideas?
I'll probably take it by Chevy soon when I can find time.
Thread Starter
Drifting
Joined: Oct 2014
Posts: 1,733
Likes: 403
From: Atlanta, GA
Update:
just had had her at the dealer. Could not duplicate.
Of course
I explained to a couple techs that this car, since I've owned it, has had a rock steady engine temp of 200. Maybe 205-210 after a hard acceleration tops. But lately the temp range has been "sloppy".
Sooooo, this other tech would like to have it for longer when it's convenient for me. The next few weeks suck for timing plus I have a road trip from Atlanta to Daytona in 4 weeks.
just had had her at the dealer. Could not duplicate.
Of course
I explained to a couple techs that this car, since I've owned it, has had a rock steady engine temp of 200. Maybe 205-210 after a hard acceleration tops. But lately the temp range has been "sloppy".
Sooooo, this other tech would like to have it for longer when it's convenient for me. The next few weeks suck for timing plus I have a road trip from Atlanta to Daytona in 4 weeks.
Race Director
Joined: Mar 2001
Posts: 19,965
Likes: 6,770
From: Bonneville Salt Flats
I had what sounds like an identical issue once and only once with my '01 C5... though, I never monitored the temps that closely, before or after. So, I cannot speak to that aspect.
However, after I thought about the issue at the time, I was not sure that the fans had turned on when it overheated. As I say, this has never happened again in the intervening 7 or 8 years. I still have and drive the car semi-regularly without further incident.
However, after I thought about the issue at the time, I was not sure that the fans had turned on when it overheated. As I say, this has never happened again in the intervening 7 or 8 years. I still have and drive the car semi-regularly without further incident.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Melting Slicks
Joined: Jan 2001
Posts: 2,996
Likes: 304
From: MOORESVILLE NC
Update:
just had had her at the dealer. Could not duplicate.
Of course
I explained to a couple techs that this car, since I've owned it, has had a rock steady engine temp of 200. Maybe 205-210 after a hard acceleration tops. But lately the temp range has been "sloppy".
Sooooo, this other tech would like to have it for longer when it's convenient for me. The next few weeks suck for timing plus I have a road trip from Atlanta to Daytona in 4 weeks.
just had had her at the dealer. Could not duplicate.
Of course
I explained to a couple techs that this car, since I've owned it, has had a rock steady engine temp of 200. Maybe 205-210 after a hard acceleration tops. But lately the temp range has been "sloppy".
Sooooo, this other tech would like to have it for longer when it's convenient for me. The next few weeks suck for timing plus I have a road trip from Atlanta to Daytona in 4 weeks.
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
When the temperature goes that high the fan should be screaming at near maximum speed and easily audible with the car at idle.
Thread Starter
Drifting
Joined: Oct 2014
Posts: 1,733
Likes: 403
From: Atlanta, GA
I was on the interstate for a little...20 minutes. Temp rose quick from engine start to getting on the interstate to about 215. Quicker than I recall on previous normal days.
While at speed, temp was 215ish.
Then after I exited the freeway I was in some minor stop and go. Nothing crazy. Thats when it began to creep up eventually hitting 255. Cant say for sure if the fan was on then. The A/C was on and actually NEVER kicked off while the temp hovered in the 250s.
Next drive (about an hour later), I definitely heard the fan and the temp stayed around 215.
Dealer visit tomorrow.
While at speed, temp was 215ish.
Then after I exited the freeway I was in some minor stop and go. Nothing crazy. Thats when it began to creep up eventually hitting 255. Cant say for sure if the fan was on then. The A/C was on and actually NEVER kicked off while the temp hovered in the 250s.
Next drive (about an hour later), I definitely heard the fan and the temp stayed around 215.
Dealer visit tomorrow.
Racer
Joined: Aug 2000
Posts: 323
Likes: 51
From: Arlington tx
I was on the interstate for a little...20 minutes. Temp rose quick from engine start to getting on the interstate to about 215. Quicker than I recall on previous normal days.
While at speed, temp was 215ish.
Then after I exited the freeway I was in some minor stop and go. Nothing crazy. Thats when it began to creep up eventually hitting 255. Cant say for sure if the fan was on then. The A/C was on and actually NEVER kicked off while the temp hovered in the 250s.
Next drive (about an hour later), I definitely heard the fan and the temp stayed around 215.
Dealer visit tomorrow.
While at speed, temp was 215ish.
Then after I exited the freeway I was in some minor stop and go. Nothing crazy. Thats when it began to creep up eventually hitting 255. Cant say for sure if the fan was on then. The A/C was on and actually NEVER kicked off while the temp hovered in the 250s.
Next drive (about an hour later), I definitely heard the fan and the temp stayed around 215.
Dealer visit tomorrow.
Thread Starter
Drifting
Joined: Oct 2014
Posts: 1,733
Likes: 403
From: Atlanta, GA
i know all of you are the edge of your seats about this. LOL
They're hooking up a bunch of sensors to her then going for a drive. Possibly a rogue indication. No codes came up from interrogation.
Who knows...
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
With the driving you were doing coupled with ambient temperature this time of year you were probably just on the cusp of a "limp" overheat and continued low speed driving and extensive idling would have caused the overheat condition. The sensors are more reliable than relays, fan motors, thermostats, etc. so generally an overheat indication really is an overheat condition.
Racer
Joined: Mar 2015
Posts: 345
Likes: 108
Overheating
Ask the dealer to check the A/C pressures with their scan tool and compare them to expected values. A/C pressures are one of the triggers that starts the fan. If your A/C was not blowing cold when the overheat happened, it might be related to the A/C system.
Drifting
Joined: Apr 2013
Posts: 1,743
Likes: 453
From: Saint Clair Shores Mi
OP: I hope they find it for you. I used to live in ATL, nothing worse than over-heat in ATL traffic on I-75 or I-285 in the middle of 6 lane traffic, no place to go, and for sure nobody will let you over!!
I kind of agree with several posts above, it sounds like your fan is not coming on and it's intermittent.
Best of luck and I hope they find it.
I kind of agree with several posts above, it sounds like your fan is not coming on and it's intermittent.
Best of luck and I hope they find it.
Racer
Joined: Sep 2017
Posts: 380
Likes: 93
From: Alaska
As I am still studying these (as opposed to having one) I'm curious to know if it's possible on the initial overheat (260° ) some coolant escaped.
I ask as it makes me suspect there could be a small amount of "air" in the system.
I've never had an air lock in a cooling system of any GM product I've used, ever, but is that a possibility?
I know an indication problem is far more likely, but, if it turns out to be not an indication problem, could they try pulling a vacuum on the cooling system and see what the coolant level does when it is released?
For clarity, I do mean a hard vacuum like I could do with a Mity-Vac, I'm sure they have something fancier.
I ask as it makes me suspect there could be a small amount of "air" in the system.
I've never had an air lock in a cooling system of any GM product I've used, ever, but is that a possibility?
I know an indication problem is far more likely, but, if it turns out to be not an indication problem, could they try pulling a vacuum on the cooling system and see what the coolant level does when it is released?
For clarity, I do mean a hard vacuum like I could do with a Mity-Vac, I'm sure they have something fancier.
Last edited by Nexxussian; Nov 8, 2017 at 03:53 PM.
Team Owner
Joined: Aug 2000
Posts: 24,110
Likes: 1,331
From: Spring Texas
