Normal Operating Coolant Temperature

[wutanec]

Learning so many new things about the ZR!
I was sitting in a traffic today and saw the temperature moving past the middle and closer to the upper end of it.
As soon as I drove off, It dropped below the middle line again.
I've attached a picture of the coolant temp gauge when it was at its highest.
it was after idling for a few minutes after a drive

Is this normal to see the needle so high?

Also after searching the forum, a lot of guys are stating specific temperature that they read. How are you guys getting the actual number for the temperature?

[We Gone]

If its still stock you can see temps up to 230 + or - 5. Best thing you can do is get a prom with the fans reprogramed Mine are both on 210 off 205 never see temps over 210 190s most the time.

http://zr1specialist.com/HAT%20Web/products/LT5%20Performance%20Engine%20Calibrations.htm

[wutanec]

If its still stock you can see temps up to 230 + or - 5. Best thing you can do is get a prom with the fans reprogramed Mine are both on 210 off 205 never see temps over 210 190s most the time.

http://zr1specialist.com/HAT%20Web/products/LT5%20Performance%20Engine%20Calibrations.htm

It is stock as far as I know. Interesting......would it be bad for the engine to run at ~230 for a prolonged time? what are the benefits of lowering the max temp down to 210?

[Dynomite]

I was sitting in a traffic today and saw the temperature moving past the middle and closer to the upper end of it.
As soon as I drove off, It dropped below the middle line again.


See Item #5 Post 120 - Thermostats, Fans, Radiators and Coolant Filling (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-6.html#post1584987828)


Keep the rpm above 2,000 rpm to assure adequate coolant flow when idling in traffic.


Also after searching the forum, a lot of guys are stating specific temperature that they read. How are you guys getting the actual number for the temperature?

Using the HVAC Display parameter #16 digital readout for continuous Engine Coolant Temperature in deg C where deg F=((9/5)(deg C) +32) can be accomplished by pressing the two Fan Buttons.

Press both Fan Up and Fan Down together waiting 3 seconds to enter HVAC diagnostics. Then press Fan Up to parameter #16 and then press Auto (between the two Fan Buttons) to read the Engine Coolant Temperature in deg C which Engine Coolant Temperature will be a real time continuous reading.

Post 9 - HVAC Temperature Display And Radiator Efficiency Test Runs (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp.html#post1580070560)

[wutanec]

wow Thanks so much guys, it is super helpful. The HVAC readout is really helpful to monitor the coolant temp.

By the way, is it normal to reach 235 degrees in normal driving situation? Yesterday driving home in a cool 76 degree day, normal LA stop and go traffic on freeway, the highest temperature I've seen was 113 (235.4) and cluster gauge needle was almost reaching the cross hatched part of the dial.

[efnfast]

C4's are famous for plugged radiators

[QB93Z]

In my experience, 235 degrees while driving is high for a coolant temperature for a properly operating cooling system. If you are standing in stop-and-go traffic in 90+ heat, you may see 235 degrees.

Do you have any modifications to your ZR-1?

Verify that the coolant system is properly filled and that the overflow tank (below the right headlight) has the right amount of coolant


I strongly suggest getting a Haibeck Chip for your ECM.http://zr1specialist.com/HAT%20Web/products%20index.htm


Verify that both of the radiator cooling fans are operating properly. These are the fans that are mounted to the back of the radiator (facing the engine).


Inspect the front of the radiator stack (oil cooler - AC Condenser - Radiator) for debris and obstructions.


Jim

[Dynomite]

If you are standing in stop-and-go traffic in 90+ heat, you may see 235 degrees.

Verify that both of the radiator cooling fans are operating properly. These are the fans that are mounted to the back of the radiator (facing the engine).

Inspect the front of the radiator stack (oil cooler - AC Condenser - Radiator) for debris and obstructions.
Jim

In addition to what Jim suggests...…..if you are driving in 100 deg F + heat......keep your idle above 2,000 rpm at all times (Under extreme temporary conditions in High Heat....turn your AC OFF).

See Item #5 Post 120 - Thermostats, Fans, Radiators and Coolant Filling (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-6.html#post1584987828)

Keep the rpm above 2,000 rpm to assure adequate coolant flow when idling in traffic.

[Hib Halverson]

Learning so many new things about the ZR!
I was sitting in a traffic today and saw the temperature moving past the middle and closer to the upper end of it.
As soon as I drove off, It dropped below the middle line again.
I've attached a picture of the coolant temp gauge when it was at its highest.
it was after idling for a few minutes after a drive

Is this normal to see the needle so high?(snip)

Know that the analog gauges in the late C4 IP are inaccurate. This was a problem because the digital display in "early, late-C4 IP" does not support engine coolant temperature (ECT). As you've already found out you have to program the HVAC to display ECT (in centigrade).

As your ECT comes down as cooling airflow increases, I would suggest...

1) Verify that the coolant is filled to the proper level.
2) Verify that the coolant is the proper mix, ie: 50/50 antifreeze/water
3) Make sure the front air dam is intact and functional
4) Verify the cooling fans are working properly.
5) Remove the top of the cooling stack and inspect the spaces between the HVAC condenser, the oil cooler and the radiator. Remove debris as necessary.
6) If the coolant is "dirty" or the high-fill bottle has a lot of "icky stuff" in it, when the top of the cooling stack is off, remove the radiator and, looking though its inlet and outlet, inspect the inside of the core for possible debris restrictions. Replace the radiator if necessary.

Cooling mods you can consider...

1) Since a 28-year old electrical component could be faulty, change the ECT sensor.
2)Buy an aftermarket calibration from Marc Haibeck which reduces the fan-on temperatures.
3) Seal all holes in the top and sides of the cooling stack with black duct tape. This prevents cooling airflow from bypassing the radiator.
4) The OP reads as if this is a California car. If so, flush the cooling system then reduce the coolant mix to 15/85 and add one bottle of "Driven CSP" or "Red Line Water Wetter". This works because water is a better coolant than is antifreeze and the higher the proportion of water the better the engine cools. That said, if you decide to do this you must use one of those two additives and you must change the coolant every two years regardless of mileage.
5) Replace the stock radiator with an aftermarket, all-aluminum unit made by DeWitts.

[Paul Workman]

Know that the analog gauges in the late C4 IP are inaccurate. This was a problem because the digital display in "early, late-C4 IP" does not support engine coolant temperature (ECT). As you've already found out you have to program the HVAC to display ECT (in centigrade).

As your ECT comes down as cooling airflow increases, I would suggest...

1) Verify that the coolant is filled to the proper level.
2) Verify that the coolant is the proper mix, ie: 50/50 antifreeze/water
3) Make sure the front air dam is intact and functional
4) Verify the cooling fans are working properly.
5) Remove the top of the cooling stack and inspect the spaces between the HVAC condenser, the oil cooler and the radiator. Remove debris as necessary.
6) If the coolant is "dirty" or the high-fill bottle has a lot of "icky stuff" in it, when the top of the cooling stack is off, remove the radiator and, looking though its inlet and outlet, inspect the inside of the core for possible debris restrictions. Replace the radiator if necessary.

Cooling mods you can consider...

1) Since a 28-year old electrical component could be faulty, change the ECT sensor.
2)Buy an aftermarket calibration from Marc Haibeck which reduces the fan-on temperatures.
3) Seal all holes in the top and sides of the cooling stack with black duct tape. This prevents cooling airflow from bypassing the radiator.
4) The OP reads as if this is a California car. If so, flush the cooling system then reduce the coolant mix to 15/85 and add one bottle of "Driven CSP" or "Red Line Water Wetter". This works because water is a better coolant than is antifreeze and the higher the proportion of water the better the engine cools. That said, if you decide to do this you must use one of those two additives and you must change the coolant every two years regardless of mileage.
5) Replace the stock radiator with an aftermarket, all-aluminum unit made by DeWitts.

Thanks Hib, for the post. Just wanted to include a tip:

A (galvanized) wire screen (with 1/4" squares from ACE HARDWARE, or wherever), fashioned and stretched across the gap between the AIR DAM and the bumper will prevent the majority of the debris, e.g., grass clippings (especially), from getting in there in the first place. It's a little mod well worth spending an hour on!:thumbsup:

[aafc]

I race my car a few times a year and cooling can be a problem at times.
Back about 8 years ago A/O ENGINEERING had a system called AUX a set of 1
2 or 3 small fans mounted into the upper wheel wells. I used 3 fans on each
side. Each fan was rated to pull 50 cu ft of air from under the car when the
main fans come on. This was fine as long as you are not settings in traffic .To
help cool the car I installed a switch so i could turn on the fans when ever
i though the temp would get to high.So sitting in traffic i turn on the fans
before the coolant gets to high. When the fans come they pull about 300
cu ft.
of air out from under the hood and also turn on the main fans to pull air
trough the radiator while car is not moving. So far this system has worked
very well for me, i just have to pay attention to the temp. My avg temp
when outside temp is 88-92 deg is between 185-200 deg.
That is with out turning the fans on and normal driving.

Right now i"am working on getting my auto transmission temp down as
much as possible due to high stall converter i run.
john
1990 white/black #2546
one of a few auto ( 4l80E ) EQ ZR-1's