High engine temp warning after changing thermostat
Thread Starter
Instructor
Joined: Aug 2006
Posts: 163
Likes: 0
From: duluth minnesota
High engine temp warning after changing thermostat
I just changed to a 160 degree thermostat on my c6 refilled the overflow a few times as it went down-until it stayed in the full range. When i drove the car the temp stayed at 185 ish,then the gauge went down to the bottom 100 degree area and the dic display read - Hot engine air conditioning off- I drove home 5 miles and the coolant temp was shown as XXX ,the oil temp was only 175, and the engine did'nt really seem hot. Any ideas what happened.
Instructor
Joined: May 2005
Posts: 196
Likes: 0
From: Bradenton FL
Try putting back your old one and see what happens. I didn't have problem with my C6 but had similar problem on my c5. After I changed thermostat I drove down road to test it. About 2 miles from my house I was sitting at red light, temp went past 200, kept climbing, light turned green, then I pulled over, few seconds later, engine shut off. I opened hood and it over heated. To be safe, I called AAA then towed it to my house, put old thermostat in, car was fine, ordered new 160 thermostat. Installed new one then no problem. Hope that helps.
Thread Starter
Instructor
Joined: Aug 2006
Posts: 163
Likes: 0
From: duluth minnesota
I guess it was caused by filling the resivour while the car was running, I disconnected the neg.battery cable,reconnected it and the message was gone ,the gauge read fine while, while at 55 mph it held at 165 degrees. Thanks.
Team Owner
Joined: Oct 2004
Posts: 27,420
Likes: 64
From: San Clemente CA
Thread Starter
Instructor
Joined: Aug 2006
Posts: 163
Likes: 0
From: duluth minnesota
I only drove it a few miles maybe it will happen again tomorrow if i go farther. THanks again guys. Eric
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Check the connector to the sensor on the drivers side head near the alternator. Disconnect it and reconnect. If the temp is falling to 100 the sensor may be bad (or the connector)
Safety Car
Joined: May 2000
Posts: 4,821
Likes: 347
From: Albuquerque NM
Been there, had that happen. Scared the wee outta me!
It's not a physical problem, your engine is fine, you don't have air pockets, you don't have an actual overtemp condition.
The PCM has detected that you are running a lot cooler than it thinks you should and it's response is too display these warnings. Who knows why it was programmed to to this. You need to get your tuner to turn off the undertemp trouble code and you will be fine.
It's not a physical problem, your engine is fine, you don't have air pockets, you don't have an actual overtemp condition.
The PCM has detected that you are running a lot cooler than it thinks you should and it's response is too display these warnings. Who knows why it was programmed to to this. You need to get your tuner to turn off the undertemp trouble code and you will be fine.
Le Mans Master
Joined: Dec 2005
Posts: 7,753
Likes: 210
From: North Western Connecticut
.. mine did the same thing! You think it's full but it's not. Took my about 5 mins to get it properly refilled. If you had the stat in upside down it would over heat the engine in nothing flat and I don't think it can be installed that way........
Race Director
Joined: Aug 2005
Posts: 13,592
Likes: 187
From: Hudson WI
NCM Sinkhole Donor
Been there, had that happen. Scared the wee outta me!
It's not a physical problem, your engine is fine, you don't have air pockets, you don't have an actual overtemp condition.
The PCM has detected that you are running a lot cooler than it thinks you should and it's response is too display these warnings. Who knows why it was programmed to to this. You need to get your tuner to turn off the undertemp trouble code and you will be fine.
It's not a physical problem, your engine is fine, you don't have air pockets, you don't have an actual overtemp condition.
The PCM has detected that you are running a lot cooler than it thinks you should and it's response is too display these warnings. Who knows why it was programmed to to this. You need to get your tuner to turn off the undertemp trouble code and you will be fine.
Le Mans Master
Joined: Feb 2006
Posts: 5,762
Likes: 4
From: Chandler Arizona
165 is really cold. I have a 160 and it stays at 178 on a cold day while cruising. I've never seen anything less than that once the car warms up.
Team Owner
Joined: Aug 2003
Posts: 38,314
Likes: 35
I just changed to a 160 degree thermostat on my c6 refilled the overflow a few times as it went down-until it stayed in the full range. When i drove the car the temp stayed at 185 ish,then the gauge went down to the bottom 100 degree area and the dic display read - Hot engine air conditioning off- I drove home 5 miles and the coolant temp was shown as XXX ,the oil temp was only 175, and the engine did'nt really seem hot. Any ideas what happened.
If you think its an air pocket, put the car on ramps so that the pocket rises towards the top, start it up with the lid off the reservour and see if the coolant level goes down. If it does then add more coolant/water mixture.
I'd definitely rule out an air pocket first and foremost as this is perhaps the most common "error" in installing a thermostat.
Safety Car
Joined: May 2000
Posts: 4,821
Likes: 347
From: Albuquerque NM
I'm thinking you got an air pocket. But the post by C6 Speeder definitely deserves a lot of consideration.
If you think its an air pocket, put the car on ramps so that the pocket rises towards the top, start it up with the lid off the reservour and see if the coolant level goes down. If it does then add more coolant/water mixture.
I'd definitely rule out an air pocket first and foremost as this is perhaps the most common "error" in installing a thermostat.
If you think its an air pocket, put the car on ramps so that the pocket rises towards the top, start it up with the lid off the reservour and see if the coolant level goes down. If it does then add more coolant/water mixture.
I'd definitely rule out an air pocket first and foremost as this is perhaps the most common "error" in installing a thermostat.
I don't know why some do this and some don't. My guess is the computer expects to see a certain temp with in some finite time after startup, low ambient temps and low load during warmup may cause it to not come up fast enough with a low temp stat. I do know that after turning off that code it hasn't happened again, and still running considerably cooler than stock.
Advanced
Joined: Apr 2006
Posts: 88
Likes: 0
From: RINGWOOD NJ
Thats exactly what happened to my o6 only a certain serial range does it. A friends built the same week as mine also did it . Had to have the code changed when I had it tuned, problem never appeared again.
Instructor
Joined: Dec 2006
Posts: 145
Likes: 0
From: broussard La
An Old Thermostat Trick
Years ago I read something that Smokey Yurchan[sic] did to his cars its worked for me for many different cars. Here goes by the way I have read this from some other guys here also so I'm not the only one. I drill acouple of 1/8 or slighly large hole . I also insist on fail open thermostats. The good ones always have 2 springs. The holes prevent AIR POCKETS. they also allow enough water to help prevent serious overheating. I just changed my 07 C6 to 160' it drastically lowered the temps from 203-208 to 183-189. this is my experience ,no reprograming in my case. no water wetter either. I do use the AC all the time and keep the dust out. I hope it works out for you try the holes, there is already one there with a swivel thing that must go IMOP