07' Z06 Overheating or am I being crazy?

2184 Views 23 Replies 9 Participants Last post by Jonathan Lemans Blue C6, 25 d ago

maynard4711

Discussion Starter · 7 mo ago

I have an 07 Z06 that I got back in May of this year; it had just under 39k miles on it when I purchased it and right now it's somewhere close to 45k.
In the last month or so I've noticed that when I'm cruising the coolant temp stays between 217 and 223 depending on the speed I'm running but coming to a stop it shoots up almost instantaneously to just under 230, between 225 and 230 most of the time. I really don't recall it ever having this much fluctuation... I've always kept a pretty close eye on it and I don't recall it ever getting much over 220 or 221 up until recently.

I've checked for airflow obstructions and I've watched the thermostat cycle using a IR thermometer.
The fan comes on somewhere around 225 but it seems like it always stays on high (as I understand it these fans have an auto speed adjust).
I've seen in other forums where the temp should not exceed 220, and is usually somewhere between 212 and 217, is that under load or is that idling?
What is the standard idling temp for these things after it's warmed up? What is the standard temp with this car under load, after warm up?

Since the car is getting close to 50k, should I go ahead and get a coolant service done?
Lastly, does anyone know any good Vette mechanics in the Nashville, TN area?

I'm probably just being overprotective getting myself worked up for nothing.
Any feedback or input would be greatly appreciated.

Chuck

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racingvette

· #2 · 7 mo ago

You need to understand how GM commands the coolant fans, which is within the PM calibration
PCM commands what the percentage of the fan's rotation is
Looking within your Z06, the fans are only commanded to rotate 14.9% and that does not begin until 219 F deg
And does not go even then 89.9% speed of rotation until 233 Deg

PCM will also command the fans higher rotation when the A/C is on, so you may see cooler temps then and now with it off the temps can be higher

If wanting the temps to be lower than have someone tune the PCM calibration and change the values shown below
Stock Tstat is like 192 deg so as you see the coolest temp PCM can command is 89 C so with tune start commands fans on then and up the rotation throughout this table

Also swap Tstat with like a 175 % and with setting higher fans rotation will help bring down the engine bay temps
which also means the air in intake and gas in fuel rails be cooler and better charge to the cylinders

Only reason GM forces the higher temps is for smog reason but learned their lessons as look at the design of C8 which has more and larger coolers and engine temps run cooler

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krafty1

· #3 · 7 mo ago

For one thing your car is going on 16 years !! You should have changed your coolant 3X's already to this point and is due now also. I would also put in a new tstat,but NOT a 175. You will eventually have issues. GM engineered motor to run optimum in the 195-210 range.

racingvette

· #4 · 7 mo ago

GM does NOT optimize the calibrations, they can care less about performance
Their calibrations are about meeting SMOG and to limit GM new warranty claims

Any GM vehicle will gain on average 30 HP gains for an all stock engine with a PCM tune.
C8s coolant now run cooler than past Corvette gens so the run hot cyberspace theory is not valid
Engine makes more power with colder air/fuel charges to cylinder, not hotter and by running cooler
reduces lean AFRs which then take some load off the fuel injectors that are a bit too small to handle long
term high RPM/loads, such as in racing.

Lastly, GM learned the hard way with the lost class action lawsuits of Z06 owners who when racing due
to hot coolants caused PCM to go into limp mode and reason C8 is designed to run much cooler and a Tstat of 175 Deg is not going to prevent the fans control by PCM to run less than 89 C if PCM is tuned

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maynard4711

Discussion Starter · #5 · 7 mo ago

krafty1 said:
For one thing your car is going on 16 years !! You should have changed your coolant 3X's already to this point and is due now also. I would also put in a new tstat,but NOT a 175. You will eventually have issues. GM engineered motor to run optimum in the 195-210 range.

Thanks for the info! I bought the car in May and I have a folder with all the service records; it has been serviced a couple times between being sold new and now.
You think that the age is a factor on why it's running hotter that what I think it should? To my knowledge, since I purchased the car, I've never seen it anywhere near 195-210 once it's warmed up.
I planned on getting it serviced once it hits 50k miles but I'm certainly fine with doing it sooner if you think it will help the current issue.

maynard4711

Discussion Starter · #6 · 7 mo ago

racingvette said:
GM does NOT optimize the calibrations, they can care less about performance
Their calibrations are about meeting SMOG and to limit GM new warranty claims

Any GM vehicle will gain on average 30 HP gains for an all stock engine with a PCM tune.
C8s coolant now run cooler than past Corvette gens so the run hot cyberspace theory is not valid
Engine makes more power with colder air/fuel charges to cylinder, not hotter and by running cooler
reduces lean AFRs which then take some load off the fuel injectors that are a bit too small to handle long
term high RPM/loads, such as in racing.

Lastly, GM learned the hard way with the lost class action lawsuits of Z06 owners who when racing due
to hot coolants caused PCM to go into limp mode and reason C8 is designed to run much cooler and a Tstat of 175 Deg is not going to prevent the fans control by PCM to run less than 89 C if PCM is tuned

I'm open to any and all suggestions, just don't want to screw the car up.
This is the first one I've owned and I looked for a really long time to find it.
Thanks very much for the input.

racingvette

· #7 · 7 mo ago

Specially formulated optimum service intervals, the coolant can last up to 5 years or 150,000 miles. (Maintenance needs vary with different uses and driving conditions. See your Owner's Manual for more information)
Helps provide resistance to corrosion by protecting brass, cast iron, steel, solder, and copper components. Also provides superior high-temperature protection for aluminum components
Non-silicate formula retains excellent heat transfer characteristics for optimum water pump life
Long shelf life: storage-stable for 8 years

If past owner did proper maintenance and kept records, see when they last changed the Dex-Cool
Being a simple job you could just change it and go from there but of course is weather cooling down
you might not see higher temps till next summer

But the 427 CI LS7s always run hotter coolant temps and if not getting warning on DIC then you're seeing close to normal readings

Jonathan Lemans Blue C6

· #8 · 6 mo ago

2

maynard4711 said:
I have an 07 Z06 that I got back in May of this year; it had just under 39k miles on it when I purchased it and right now it's somewhere close to 45k.
In the last month or so I've noticed that when I'm cruising the coolant temp stays between 217 and 223 depending on the speed I'm running but coming to a stop it shoots up almost instantaneously to just under 230, between 225 and 230 most of the time. I really don't recall it ever having this much fluctuation... I've always kept a pretty close eye on it and I don't recall it ever getting much over 220 or 221 up until recently.

I've checked for airflow obstructions and I've watched the thermostat cycle using a IR thermometer.
The fan comes on somewhere around 225 but it seems like it always stays on high (as I understand it these fans have an auto speed adjust).
I've seen in other forums where the temp should not exceed 220, and is usually somewhere between 212 and 217, is that under load or is that idling?
What is the standard idling temp for these things after it's warmed up? What is the standard temp with this car under load, after warm up?

Since the car is getting close to 50k, should I go ahead and get a coolant service done?
Lastly, does anyone know any good Vette mechanics in the Nashville, TN area?

I'm probably just being overprotective getting myself worked up for nothing.
Any feedback or input would be greatly appreciated.

Chuck

Hello, Jonathan here, (Victory Red, 09 ZO6)

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maynard4711 said:
I have an 07 Z06 that I got back in May of this year; it had just under 39k miles on it when I purchased it and right now it's somewhere close to 45k.
In the last month or so I've noticed that when I'm cruising the coolant temp stays between 217 and 223 depending on the speed I'm running but coming to a stop it shoots up almost instantaneously to just under 230, between 225 and 230 most of the time. I really don't recall it ever having this much fluctuation... I've always kept a pretty close eye on it and I don't recall it ever getting much over 220 or 221 up until recently.

I've checked for airflow obstructions and I've watched the thermostat cycle using a IR thermometer.
The fan comes on somewhere around 225 but it seems like it always stays on high (as I understand it these fans have an auto speed adjust).
I've seen in other forums where the temp should not exceed 220, and is usually somewhere between 212 and 217, is that under load or is that idling?
What is the standard idling temp for these things after it's warmed up? What is the standard temp with this car under load, after warm up?

Since the car is getting close to 50k, should I go ahead and get a coolant service done?
Lastly, does anyone know any good Vette mechanics in the Nashville, TN area?

I'm probably just being overprotective getting myself worked up for nothing.
Any feedback or input would be greatly appreciated.

Chuck

Good morning! Jonathan here,(615.587.0943) from Hendersonville TN.

I don't check the Forum every day, best to call or text, if you'd like to talk.

I've had some "issues" with my 09 ZO6 cooling.

I'd rather talk on phone than fill in all the information, here...

Currently have 2 Vettes with 427s, an 05 with a fairly modified 08, 6.2 with LS7 ported heads, and accompanying upgrades, cam,etc., .

An 09 Z06, with American Heritage Racing heads, Billy Boat mufflers, otherwise stick drivetrain.

That said, I have 2 area Mechanics that I use.

#1 , Wesley Hendley 615-587-1746, Goodlettsville TN, formerly worked for KMF Racing Engines of Dickson TN.

He now Owns the Business.

He built the 08, 6.2/7.0 heads , 521 rwhp engine and installed it and the accompanying drivetrain upgrades. All NA.

It's a screamer!

#2 is Erin Carpenter, of CARMA PERFORMANCE, 1035 3rd Avenue S. Nashville Tennessee 37210
615-730-8654, he tuned the 6.2/7.0 and adjusted drive-ability issues.

He really stands behind his work!

Tell him Wesley and Jonathan Hendley, blue 05 w that 6.2/7.0 heads engine, sent you.

He and his Shop do all kinds of performance upgrades and tuning, with lots of C5/C6,C7 experience.

#3 is Not local, but he is a Expert imhop on C6s and Z06 s.

Stephen Gilbert, of Southhaven Mississippi, rt by Memphis. I'd need to give him a heads-up if you want to talk to him, as he doesn't answer calls from unknown #s.

Best to you, glad to help a Brother in Vettes if I can,

Jonathan

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Jonathan Lemans Blue C6

· #9 · 6 mo ago

PS, I did do a complete flush and service, added high quality coolant and coolant booster w additives for neutralizing currents that causes corrosion. Operating temperatures are better, warm-ups faster.

Bruno

· #10 · 6 mo ago

Just to give you a reference, I took my car out this past Monday our temps were around the upper 40's low 50's. I was on the highway running 75 ish and watched my coolant temp climb to 198*. Shortly after that the fans must have kicked on and the temp dropped quickly to 192*-194* and stayed there. My car been tuned and my fans come on earlier and run faster the the stock program.
I change my coolant and brake fluid every 3 years now. If you ever see what expired coolant or contaminated brake fluid do to your car, you will find that changing them early and on a regular basis will save you a lot of headaches.
My car is a '13 with 15,500 miles on the odometer, it will sit from mid December until usually mid March. Lots of idle time for things to go wrong.

Jonathan Lemans Blue C6

· #11 · 6 mo ago

Sounds like it's running good to me!
How's your oil temp?
CARMA PERFORMANCE, Erin Carpenter, 615-730-8654 , would be my go to on temp issues

Bruno

· #12 · 6 mo ago

Oil temp usually mirrors the coolant temp. I think a few times when I was doing several WOT pulls trying to get some good data for my tuner I may have reached 210*- 212* max.

Eighthtry

· #13 · 6 mo ago

I have a 2018 Z06/07. Summer temps run plenty warm. Winter temps run 175-180 with similar oil temps. Summer runs every bit of j210-215. I do not track the car. That is running down the freeway. I am not sure why the differences.

Jonathan Lemans Blue C6

· #14 · 6 mo ago

Bruno said:
Oil temp usually mirrors the coolant temp. I think a few times when I was doing several WOT pulls trying to get some good data for my tuner I may have reached 210*- 212* max.

Interesting, my 09 only gets up to 169°+-2/3 at 80-85 mph cruise, and occasional 100 mph+- bursts...I will need to check with my Z06 expert friend tonight, and see if the oil system is is same 07-09. Going to see him somewhere around 8pm tonight, 12/3/22

pbstull

· #15 · 6 mo ago

I have an 07 as well with a Magnuson SC. I put in a Dewitts (drop in interchange) a few years ago and it cools much better now. Definitely worth the expense and install time.

maynard4711

Discussion Starter · #16 · 2 mo ago

Thanks everyone for the input...
RECAP: My coolant temps were running between 220 and 226 at freeway speed and would spring up to 230 in traffic.
It actually got worse over time and stayed between 225 and 228 at freeway speed and would spring up to 230 in traffic - occasionally 232.
The oil temp was staying between 190 and 210 depending on speed / load.

UPDATE: I changed the oil to 5/30 Amsoil, changed the thermostat to 180 degree and flushed the coolant / changed the coolant to Amsoil... and, I added an Amsoil coolant boost.
Coolant temps now have not gone over 217 in traffic and usually stay below 208 on the freeway... I've even seen it at speed as low as 199.
I haven't seen the oil temp above 169 degrees +- 2/3 and I've been driving it around for about 3 days now since I've done the work.

BIG Thanks to Jonathan Lemans Blue C6 for taking time to talk on the phone and for all the input!
This thing is running like I want it and couldn't be happier. The Amsoil even quietened down that old LS rattle, lol.

I don't mean to make this a commercial for Amsoil but give it a try if you're not using it already... I'm impressed.

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Bruno

· #17 · 2 mo ago

I have been using AMSOIL for several years now and have become a preferred club member. Between the extra discounts, free shipping, free preferred club membership I won’t use any other product. I am about to put their trans oil in my tranny when I do my spring oil change. My TR6060 has the dreaded 1st to 2nd hang up when cold. I’ve read the other owners have changed to their fluid and no longer have that problem.

maynard4711

Discussion Starter · #18 · 2 mo ago

I haven't heard about the 1st to 2nd hang up when cold. I'm pretty sure I haven't experienced it yet, hopefully I won't.
I have experienced the CAGS (computer aided gear selection) that forces you to skip 2nd gear straight to 4th.
I had no idea what it was and it scared me to death... I just new my transmission or clutch was going out... and right after I bought the car no less.
I called every mechanic I knew. Ended up finding the answer to that one on one of these forums.

So far I'm loving AMSOIL. Great product!

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Bruno

· #19 · 2 mo ago

You probably don't have the trans shift issue because you have a T-56 Tremec not a TR6060. As for the CAGS I just have my tuner eliminate the feature.

Jonathan Lemans Blue C6

· #20 · 2 mo ago

maynard4711 said:
Thanks everyone for the input...
RECAP: My coolant temps were running between 220 and 226 at freeway speed and would spring up to 230 in traffic.
It actually got worse over time and stayed between 225 and 228 at freeway speed and would spring up to 230 in traffic - occasionally 232.
The oil temp was staying between 190 and 210 depending on speed / load.

UPDATE: I changed the oil to 5/30 Amsoil, changed the thermostat to 180 degree and flushed the coolant / changed the coolant to Amsoil... and, I added an Amsoil coolant boost.
Coolant temps now have not gone over 217 in traffic and usually stay below 208 on the freeway... I've even seen it at speed as low as 199.
I haven't seen the oil temp above 169 degrees +- 2/3 and I've been driving it around for about 3 days now since I've done the work.

BIG Thanks to Jonathan Lemans Blue C6 for taking time to talk on the phone and for all the input!
This thing is running like I want it and couldn't be happier. The Amsoil even quietened down that old LS rattle, lol.

I don't mean to make this a commercial for Amsoil but give it a try if you're not using it already... I'm impressed.

Your #'s are very similar to mine now, in my 09 Z06. I don't use the Forum to promote AMSOIL, but when a product works THIS well, you just have to put it out there!
Thanks for the kind words 🙏

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