My C8 Z51 on Z Mode seemed to be running hot in stop and go traffic on a 90 degree day. Coolant and Oil temp got up to 215/213- which seemed high to me. When running on freeway temp cooled down to 198-205 - Levels were checked and they were both fine. Is this normal?????

 

Normal

 

I live in the Phoenix area, and noticed temps in the 205-210 area while on Z mode and Track mode after mild romps. Nothing to worry about, system is pressurized and can handle higher temps than that. That said, I am considering adding the second front radiator as I saw someone on the forum do last year. Tracking the car here, even in milder weather, will start taxing the cooling system, as well as the engine oil and trans fluid.

Semper Fi!

 

Modern cooling systems run hotter than in the old days because it makes it easier to control emissions.

 

No problem. I would expect that on a 90 Degree day. That is not hot.

 

Running too hot. Also live in the Phoenix area, in my 5 years with the Z51 Stingray the hottest the oil ever gets is 190*. Typical day of 90 to 100° day oil runs 178° - 182*. With the Soler throttle controller this car gets plenty of high rev shifts, live in an area being retired and on the weekends where it's easy to exceed 100. Do you use any air restriction items on the front of your car?

 

My C8 never goes above 205 even when it's 100+ outside, and your Z51 has additional cooling.

 

Where are you? I'm in Florida with high humidity and temperature......172 on highway and around 180/185 stop and go.

 

i’m in Fort Lauderdale and if it truly is stop and go with an accident or such and you’re crawling along for 10 to 15 minutes, I’ll go to 215 to 220… No problem

I forget which Chevy website this was on, but one of the Tech websites put this up a year or so ago:

normal engine readings once warmed up

water temp 190 -210

oil press in the 30's

oil temp 170-190

 

Sorry, I meant traffic ligjt to traffic light. Stop and go for an incident/accident, 212 but fluctuates down from there.

 

I’ve seen 208-210 a few times in my stingray but my Z06 seems to run a little cooler.

driving on a hot day 160-170s in the Z, 170-180s in the stingray.

idle/traffic, 190-200 in the Z, 200-210 in the stingray.

seems like your car is normal

 

Not sure. While the coolant temperature is within the "Normal" range - indicated by the Service Manual as between 190 deg and 221 deg F when idling at "normal operating temperature", I think what you are asking is more like "is this typically what others see under the same conditions?" I'm not sure since conditions vary a lot - both ambient conditions and also operational conditions - but I typically do not see temperatures that high. Regarding operational conditions you mentioned Z mode, but Z mode is entirely customizable. The setting that might affect operating temperature is the engine/shift setting, since is will affect automatic gear selection. But so will use of the throttle and manual selection of gears - to some extent. The Z51 has considerable excess cooling capacity - much more than you could safely challenge on the street. Other than checking the coolant level and the front and side inlets to make sure they are clear - that's it. Do you have front/side inlet screens? What kind?

Operating Conditions: Engine = Idling - At normal operating temperature.
Parameter Normal Range: 88 to 105°C (190to 221°F)

 

I drove my Z51 through Death Valley during record heat and didn't exceed 200F (and I have front screens installed). But that is when the car was moving and not completely relying on the cooling fans to draw in air. It runs hotter in stop and go traffic.

The way the system works the thermostat controls engine coolant temperature until it is wide open but the engine is still exceeding its temperature parameters under those conditions. The cooling fans then turn on to move more air through the radiators (the fans may already be on if the AC is running). They are variable speed fans so the hotter the coolant the faster the fans run.

The faster the fans run the more power they consume which affects fuel mileage. So the computer only increases fan speed the minimum amount necessary to keep the engine within its operating parameters. This is why you see engine temperatures towards the higher end of the allowable temperature in stop and go traffic.

Running the the engine at the higher end of its normal operating temperature range doesn't hurt it.

 

I'll add a little to the explanation of the cooling fan operation. Its based on the Service Manual explanation - which may or may not be complete because its written to give techs a general understanding of how it works - not necessarily a complete explanation of every detail.

The front cooling fans are called "engine cooling fans". The conditions that cause them to activate include;
1)coolant temperature is warmer than a predetermined temperature.
2)engine oil temperature is warmer than a predetermined temperature.
3)A/C pressure reaches a predetermined pressure.
4)If the engine coolant temperature at key-off is warmer than a predetermined value, or the A/C pressure is greater than a predetermined
value, the cooling fan will operate at a low speed. The fan will shut OFF if the temperature or pressure drops below the predetermined
value, but will only operate for 2 minutes, regardless of the coolant temperature or A/C pressure.

The fans in the back are called "Engine Compartment Cooling Fans". Its described like this:
"The under-hood air temperature sensor is an input to the fuel pump driver control module. The engine control module (ECM) and fuel pump driver control module communicate via serial data. The ECM uses the under-hood air temperature sensor to determine the desired engine compartment fan speed which in turn is communicated to the fuel pump driver control module. The fuel pump driver control module controls the fan speed by sending a pulse width modulated (PWM) signal to the engine compartment cooling fan control module. The engine compartment cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal, allowing the cooling fan to operate at variable speeds."

So it relies on engine compartment temperature. And many have noticed the rear fans will actually start after the engine is turned off. Missing from the explanation of the operation of the Engine Compartment Cooling Fans is any dependence on coolant or engine oil temperature. The ECM controls it, and has access to those paramenters, so it may also use parameters to control the En gine Compartment Cooling Fans but it does not say so.

 

Interesting. I'm taking my car in tomorrow for the software recall, i'll ask about temps.
My Z51 see's over 200deg F in traffic (very few times in traffic tho), seems to run around 180-190 when moving, this is at 70-ish deg outside.

 

I've been surprised from day one at how much the coolant temps vary. My first miles were at 100+ degrees outside temp. The next morning as I left Louisianna temps went from 70+ to over 100 pretty quickly. I had about a 600 mile ride in front of me to Bowling Green. Saw a lot of 215 temps getting there. Didn't boil over until a couple days later mid way through Ohio.

 

Your C8 actually boiled over? What exactly did that? Stop and go? On the highway?

 

If it's been over 3 years don't wait like some suggest 5 to 6 years to do a quality coolant flush. I did my first coolant flush at 3.5 years, not an expensive job to stretch out the length of time. Possibly also look into replacing your thermostat with a cooler variant.

Feel the engine bay should be open as much as possible to allow for more free flowing air around the engine, exhausts and cats. What prohibits this is the engine appearance package along with a full package of front and side air intake covering screens, feel this does not help open flow going to the engine and around an air restricted engine compartment.

Not a big fan living in a high heat area like I live in having all my Intakes covered with screens and also combining the engine appearance package that doesn't allow open air flow which assists engine compartment temps. My engine compartment is as intentionally opened up as possible with no heat shields, better is my headers are cerakote ceramic coated and HJS cats are quality Kevlar blanketed. Have a lot of open air in my engine compartment is a plus.

 

Just to weigh in mine runs on the cool side.

In 80°+ weather, if it's rare that it goes above 172°. I can drive down the freeway in 4th at 75 mph and not get it hot enough to be able to check the oil. I have to do Stop and Go traffic or sit at idle for 10 to 15 minutes to get it up over 175. The service guy even commented that it took a long time just so he could get it up to temp to be sure of the oil level.

I drive for hours at 75 mph and it varies between 168 and 172.

 

That is what I get on 95 degree days we have often in SC. I often drive in Z-Mode but on rural back roads not sustained high speeds. Never use an Interstate. Don't often have long Red lights but if I do and have to sit thru 2, the coolant can get to 190 or a bit over. As soon as I am moving back to ~185 or less. 2020 C8 Z51 was the same as my current E-Ray!

SIDEBAR
BTW I had 1/4 inch hex Custom Car Grill AC Condenser protective mesh on the 2020 C8 Z51 for 4 years. Did not see a difference in coolant or oil temp on hot days. Have no mesh on the E-Ray. It does have a third coolant only Rad in the front center (same as the Z06.) It also has an extra EV Electronics coolant rad that covers ~20% of the in front right AC Condenser/Rad. The left front rad bottom ~25% is used for EV motor cooling.

Right AC Condenser/Coolant Rad is Covered ~20% with EV Electronics Cooler Rad


Center Rad Coolant Only No AC Condenser in Front