JDMricist_03

Hey guys, I've been having some problems with my '03 Z06 but right now the problem that worries me most is when sitting at a red light the temp creeps up from mid 190's to 230 in about 2 minutes but then drops back down to high 200's. It does this every time I stop for more than a few seconds like as mentioned, a red light or even drive throughs. Now I know it's not technically overheating but that's definitely running hotter than it ever has before I decided to drain and refill my coolant using 50/50 DEXCOOL and distilled water about a week ago. Prior to this, temps would be from 190 moving to around 217 stopped so I don't know why it gets so hot so fast now but takes so long to start cooling back down. As soon as I start moving the temp quickly goes back down to high 190's. This is all coolant temp btw. The radiator fans are spinning but for some reason it seems quieter than usual...I could be wrong though. My brother said when I drained and filled the coolant I could have introduced air in the system causing the temps to rise so quick on idle. Also, in case it's related (I don't think it is but I want to include as much info as possible) my climate control fan stopped working at about the same time.

Please help me get to the bottom of this as I am NOT trying to grenade my beautiful LS6 that I've never had any issues with previously. All help and advice is much appreciated and thanks in advance!

JR-01

Have you ever cleaned out your radiator and A/C condenser?

moekluse

Did you bleed it properly? If you did not bleed all the air out correctly, it will cause overheating.

bradley21ss

Mine does it too

Esser

My C5 did the same thing. After I cleaned out my radiator and condenser, my temps dropped about 20 degrees. I rarely see it go over 200 now.

Vanover

same here

TooMch

Another one for radiator/condenser clean out.

I had been doing this with a brush from underneath and was having even worse overheating than the original poster.

Also, it would overheat with the A/C on, even at highway speeds.

Finally, I removed the shroud cap and got behind the radiator with a piece of tubing that I drilled holes in attached to my compressor and blew quite a bit of debris out of it and the condenser.

So far my Temps have not gone above 217. It has not been near as hot but I've run my A/C and that hasn't caused any problems.

It's looking good,so far.

Vetteman Jack

with all the above. Make sure you have no air in the cooling system and clean out the radiator area. Those things should help bring down the coolant temp of the car.

laurent_zo6

All good advice above. You can also turn on your AC in traffic to cool down motor.

Vendor on Forum sells a high speed fan controller (also wireless):
http://www.saccitycorvette.com/HardWireCoolit.html

To clean my radiator, I use this: https://www.radiatorgenie.com
Just make sure to not get too close to the radiator fins.

Here is the info from manual:
Factory temp settings are low speed on at 226 degrees and off at 219 degrees. High speed on at 235 degrees and revert to low speed at 226 degrees. As stated both fans run at low speed and high speed and fans are commanded off by the PCM when the vehicle speed exceeds 35mph.
You can force low speed operation at 185 degrees by turning on the AC. High speed operation with AC on is still 235 degrees.

the kid C6

I thought it was turn on the heater ... or, turn off the A/C.

BlackbirdXX

Same here, low fan was shot, baked the stock radiator, changed to an ACP (dont bash me) added passive trans cooler, 170 in 70 degree weather, 196 in 100 degree weather and trans never tops 180 actually runs cooler then engine passing through coolant. 2 years no issues.

JDMricist_03

OMG! This has to be it! Thanks for that info, I had no idea about that and it totally makes sense because my A/C blower stopped working so I haven't used the A/C since and that's exactly when I started noticing my temps creep up to 228 in traffic!
I will also clean out the condenser and radiator too to see if that does anything but the engine bay is pretty immaculate but it's definitely something that shouldn't be overlooked so thanks for the suggestion guys.
Last question, how do you get the air out of the coolant system? I just drained it at the white plastic radiator drain plug and filled with 50/50 Dexcool and distilled water so idk how differently I could do it to make sure there is no air in the system.

After being such an import enthusiast for so long thinking they are far easier to work with than American cars I found this lovely car to be just as easy if not easier than anything else! I love my Corvette and am so fortunate to own one and can't think of driving anything else but it doesn't end there, even the community comes together in such a way I've never seen before on the import scene. Thanks guys, and thanks to Chevy for producing by far the best bang for the buck in not just numbers but driver satisfaction and ease of working with.

racebum

bobby777

Take off rad. cap and start car--see if it burps when warned alittle--out cap back on and drive--might have to do this afew times but all air will be out of system--let us know