Engine Temperatures Too Low
Thread Starter
Team Owner
Joined: Sep 2000
Posts: 25,002
Likes: 2,703
From: Far NW 'burbs of Chicago
St. Jude Donor '13
Engine Temperatures Too Low
2017 A8 Z51, oil cooler connected to the radiator.
During the summer, our coolant temp stayed below 200' and I didn't pay any attention to it. Oil temperature got more scrutiny but usually stayed 175'-200', if I was romping on the throttle it would get to maybe 225'. That seems normal.
Yesterday I was on a long highway trip:
Cruising speed 60-70 mph for over an hour.
Outside air temp 42'
Coolant temp 180'
Oil temp 166'-162'
When I got into a town, the oil went back up to 175', didn't note the coolant temp.
I'm wondering if the thermostat is stuck partly open, causing the coolant and oil (cooled by the coolant) to run low temps when there is lots of airflow through the radiator, but increasing somewhat in town with less air flow.
On our C6, coolant temp ran right at the thermostat temp (190') most of the time. No oil cooler on that car, so no comparison.
Can someone with a Z51/GS with the A8 tell me how your temps run in cold weather?
Thanks!
During the summer, our coolant temp stayed below 200' and I didn't pay any attention to it. Oil temperature got more scrutiny but usually stayed 175'-200', if I was romping on the throttle it would get to maybe 225'. That seems normal.
Yesterday I was on a long highway trip:
Cruising speed 60-70 mph for over an hour.
Outside air temp 42'
Coolant temp 180'
Oil temp 166'-162'
When I got into a town, the oil went back up to 175', didn't note the coolant temp.
I'm wondering if the thermostat is stuck partly open, causing the coolant and oil (cooled by the coolant) to run low temps when there is lots of airflow through the radiator, but increasing somewhat in town with less air flow.
On our C6, coolant temp ran right at the thermostat temp (190') most of the time. No oil cooler on that car, so no comparison.
Can someone with a Z51/GS with the A8 tell me how your temps run in cold weather?
Thanks!
Team Owner
Joined: Apr 2013
Posts: 26,224
Likes: 4,345
From: Chirper Island
I am far from the most knowledgeable person here, but yes those temps seem low from every experience on Corvettes I've ever had. My C7 runs 220 unless the AC is on and the RPM is up for extended times, and then it creeps up from there.
I also don't think that that's the way a thermostat works. I think once the car warms up, it opens, so it wouldn't affect your low temps being open, because it would be open anyway?
I also don't think that that's the way a thermostat works. I think once the car warms up, it opens, so it wouldn't affect your low temps being open, because it would be open anyway?
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
Hope it's not an epidemic, Jim. Looks like there's one on the Z forum, too. The guess over there is sticking thermo. Seldom read of that tho.
https://www.corvetteforum.com/forums...lain-this.html
https://www.corvetteforum.com/forums...lain-this.html
Drifting
Joined: Mar 2013
Posts: 1,705
Likes: 538
From: Hampton VA
I am far from the most knowledgeable person here, but yes those temps seem low from every experience on Corvettes I've ever had. My C7 runs 220 unless the AC is on and the RPM is up for extended times, and then it creeps up from there.
I also don't think that that's the way a thermostat works. I think once the car warms up, it opens, so it wouldn't affect your low temps being open, because it would be open anyway?
I also don't think that that's the way a thermostat works. I think once the car warms up, it opens, so it wouldn't affect your low temps being open, because it would be open anyway?
Safety Car
Joined: Mar 2018
Posts: 4,754
Likes: 1,650
A stuck thermostat could cause the problem you describe. It should be an easy fix but first wait to hear from another owner here that can tell you what the normal operating tempearture range is for the cooling system before you proceed.
Thread Starter
Team Owner
Joined: Sep 2000
Posts: 25,002
Likes: 2,703
From: Far NW 'burbs of Chicago
St. Jude Donor '13
We had this happen on our C5 many years ago- the coolant temp started running lower than normal, but not shockingly low. Since there was no oil cooler, the oil temp was a bit low but not much.
I took it to the dealer and they said the thermostat was partially sticking, it would open normally if the engine started to get hot but would not close as much as desired when the engine was running too cool.
Replaced under warranty.
So I suspect the same thing here, but am looking for numbers from other folks with similar C7's to help confirm my diagnosis.
I took it to the dealer and they said the thermostat was partially sticking, it would open normally if the engine started to get hot but would not close as much as desired when the engine was running too cool.
Replaced under warranty.
So I suspect the same thing here, but am looking for numbers from other folks with similar C7's to help confirm my diagnosis.
Race Director
Joined: May 2001
Posts: 15,323
Likes: 2,077
From: Guelph, Ontario
I know mine's doesn't have the Z51 option, and it's not a GS, however I have driven mine a lot in cooler weather (last winter I drove it quite a bit when it was at or even slightly below the freezing mark) and I have never seen the low oil temps you are seeing. If I was doing 60-70 on the highway the coolant and oil temp would both generally be in the 185-190 range. This is leaving it in drive, so that's with V4 operation. I notice if I put it in manual mode in the highway and it's entirely in V8 mode it'll run about 5-10 degrees higher in both oil and water temp.
FWIW, I find my car runs the same water and oil temp whether it's 30F outside or 90F outside, at least at a steady highway speed.
FWIW, I find my car runs the same water and oil temp whether it's 30F outside or 90F outside, at least at a steady highway speed.
Last edited by Patman; Oct 13, 2018 at 10:53 PM.
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
Le Mans Master
Joined: Oct 2014
Posts: 8,672
Likes: 2,726
From: Atlanta GA
As above , My coolant temps usually are always around 195 no matter how cold or how hot , highway or city , once in a while in a long traffic jam it might rise into the 200's but never does it run cooler .... my oil is always 10 degrees hotter that the coolant
Dave
Dave
Team Owner
Joined: Oct 2004
Posts: 25,583
Likes: 16,942
I'm betting there's absolutely nothing wrong with your car. It's your driving style.
Coolant temp is positively correlated with rpms. I've experimented with both my C7s, and if I drive in my normal style keeping revs up (2500-3000 minimum) before shifting I'm almost always at 200º and above. If I'm highway cruising and/or "granny-shifting," keeping the rpms at 2K and below around town or on the highway, it's not unusual to stay in the 180s. In cooler temps, it would be even lower.
Try paddle shifting in manual mode, shift at 3K and above, keep the revs up a bit, and you'll see much higher temps. I never use 5 and above except on the highway, and even there I almost never use 7. Since you're an A8, I suspect your driving in auto-mode most all the time, and it's shifting for fuel economy and keeping the revs very low.
Coolant temp is positively correlated with rpms. I've experimented with both my C7s, and if I drive in my normal style keeping revs up (2500-3000 minimum) before shifting I'm almost always at 200º and above. If I'm highway cruising and/or "granny-shifting," keeping the rpms at 2K and below around town or on the highway, it's not unusual to stay in the 180s. In cooler temps, it would be even lower.
Try paddle shifting in manual mode, shift at 3K and above, keep the revs up a bit, and you'll see much higher temps. I never use 5 and above except on the highway, and even there I almost never use 7. Since you're an A8, I suspect your driving in auto-mode most all the time, and it's shifting for fuel economy and keeping the revs very low.
Racer
Joined: Nov 2015
Posts: 260
Likes: 87
From: Brighton MI
Thermostat Specification temperature is when the opening process starts - Example a 195F thermostat starts to open at 195F & normally the coolant temperature will stabilize at 210F if everything is functioning as designed. A thermostat that opens early and/or does not close properly will cause coolant temperature to run lower. Many years ago 180F thermostats were normal & emissions/economy constraints tended to increase the thermostat specified. A lower opening thermostat such as 160F can increase power, while adversely affecting emissions, economy, & drivability.
Tech Contributor
Joined: Oct 1999
Posts: 41,037
Likes: 9,801
From: Charlotte, NC (formerly Endicott, NY)
Thermostat Specification temperature is when the opening process starts - Example a 195F thermostat starts to open at 195F & normally the coolant temperature will stabilize at 210F if everything is functioning as designed. A thermostat that opens early and/or does not close properly will cause coolant temperature to run lower. Many years ago 180F thermostats were normal & emissions/economy constraints tended to increase the thermostat specified. A lower opening thermostat such as 160F can increase power, while adversely affecting emissions, economy, & drivability.
Bill
Race Director
Joined: Jun 2005
Posts: 10,909
Likes: 2,701
From: Phila Suburbs 2023 C8 & 2013 650ix
Pro
Joined: Jul 2016
Posts: 555
Likes: 265
From: Idaho
17 GS A8 range device on, checked out the temps today on a road trip. Ambient temps 52-54, coolant temps after initial warm up remained steady between 180-185 and slightly less when not on the gas and cruising on a slight down grade. My yellow rpm ring shows up now and again when the outside temps are cool enough and the engine temp drops. This (yellow rpm ring) has happened a few times and has been discussed on the forum a few weeks back.
On hot days and the days my foot is heavier, all temps are higher and the engine temps are constantly 200+.
On hot days and the days my foot is heavier, all temps are higher and the engine temps are constantly 200+.
Racer
Joined: Nov 2015
Posts: 260
Likes: 87
From: Brighton MI
#14 - Bill - Thanks for posting the numbers from the Service Manual - I was looking for this information yesterday in the owners manual (evidently Chevrolet only trusts us with temperature of OEM stat if we spend the $ for the service manual).
Burning Brakes
Joined: Aug 2013
Posts: 817
Likes: 34
This happened to my 2014 Z51. The thermostat was stuck partially open and the temperatures drop like you described. The yellow lines would come back on the tachometer as well just like when the car is warming up. I was out my bumper to bumper warranty, but it was covered under the power train warranty. The thermostat and its housing were replaced.
Hope this helps.
Hope this helps.
Instructor
Joined: Jun 2006
Posts: 220
Likes: 30
From: Fairfax VA
Was running 186-196 from Virginia to Ocean City this weekend, 60's outside. Not sure if it's my imagination but the 0W40 seems to bring the coolant temps down slightly.
I wasn't getting much heat in my DD a few years ago, thought the stat was stuck open as the gauge looked low to me. Took it in, and the tech insisted that I would get a code if coolant temps were out of range after a certain amount of time. I poked around just now and found this link.(not sure I'd do the power braking exercise though). A separate reading from an infrared gun might help you decide whether you have an issue.
I wasn't getting much heat in my DD a few years ago, thought the stat was stuck open as the gauge looked low to me. Took it in, and the tech insisted that I would get a code if coolant temps were out of range after a certain amount of time. I poked around just now and found this link.(not sure I'd do the power braking exercise though). A separate reading from an infrared gun might help you decide whether you have an issue.
Last edited by Co-Vette; Oct 15, 2018 at 03:44 PM.