What's next, someone liking the C5's seats? 
Coolant Temp too low!
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 0
Coolant Temp too low!
Ha,
Am located at Northern CA, just overhauled my cooling system on my 30k miles C5Z06 by replacing the upper and lower hoses, 160 thermostat (w/ 3 small 3/16 holes tapped) and used all distilled water w/ 2 bottles Redline water wetter. I also cleaned up all debris on AC Condense and Radiator. Now coolant temp dropped to 172 w/ outside temp at 80 degree by going about 55mph. Is coolant temp too low for my car? should I changed it back to 180 thermostat w/o tapping holes on it?
thanks in advance!
racerkan
Am located at Northern CA, just overhauled my cooling system on my 30k miles C5Z06 by replacing the upper and lower hoses, 160 thermostat (w/ 3 small 3/16 holes tapped) and used all distilled water w/ 2 bottles Redline water wetter. I also cleaned up all debris on AC Condense and Radiator. Now coolant temp dropped to 172 w/ outside temp at 80 degree by going about 55mph. Is coolant temp too low for my car? should I changed it back to 180 thermostat w/o tapping holes on it?
thanks in advance!
racerkan
Last edited by Racerkan; Jul 21, 2020 at 04:13 PM.
Melting Slicks
Joined: Nov 2013
Posts: 2,049
Likes: 316
From: USA
Yes, I always run stock thermostats. Colder thermostats just set the minimum operating temperature as you discovered. I run stock thermo and it's rock solid at 195-205, unless in a track scenario etc.
Melting Slicks
Joined: Sep 2006
Posts: 2,728
Likes: 142
From: Iowa
Same here, with the exact same experience on both my C5Z's. One being a roadcourse only track car with no coolers yet and the other a supercharged car. Both run 198-205 coolant temps on the street no matter how how it gets unless they are seeing track duty.
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 0
nice, that's what I got my Z06 for but end up found a 1 owner w/ low mileage. Don't want to mess with it.
Melting Slicks
Joined: Nov 2013
Posts: 2,049
Likes: 316
From: USA
I see no reason to deviate from the stock 187. Right at 200 coolant temp is perfect I think. Oil will be about 10*-15* higher on the street depending on no oil cooler vs oil cooler setup etc. Which I think is about perfect too for hot enough to boil out fuel/water/contaminants but not too hot.
Last edited by aaronc7; Jul 21, 2020 at 07:12 PM.
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Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 0
Drove for about 20 mins, was going about 55 mph, it went down to 170ish and back to around 190 to 200 on a full stop. Think is the mix of tapped 160 thermostat, water wetter and clean up on condenser n radiator.
Racer
Joined: Mar 2017
Posts: 406
Likes: 59
From: Northern California
Interesting. I don't think i've ever seen a car stay at 170F even without a thermostat. Makes no sense to me. Certainly the c5 radiator isn't anything to write home about. Air flow isn't that good either. hmm. One of these days I am going to do a few experiments. Maybe if you are driving around in 6th gear at 55. Which is close to idle. What this data is saying is that you have enough cooling to keep the temp at whatever the tstat temp is above 170F. Maybe that is why the stock tstat is 187F? lol Personally I never drive in 6th gear. Solves the problem. 
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 0
Confirmed, outside was 70F, I drove for 20 mins, temp was up to 185 to 190. As soon as I drove up to 55mph for about 2 blocks, temp dropped to 169 F.
Last edited by Racerkan; Jul 22, 2020 at 01:29 AM.
Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl
Ha,
Am located at Northern CA, just overhauled my cooling system on my 30k miles C5Z06 by replacing the upper and lower hoses, 160 thermostat (w/ 3 small 3/16 holes tapped) and used all distilled water w/ 2 bottles Redline water wetter. I also cleaned up all debris on AC Condense and Radiator. Now coolant temp dropped to 172 w/ outside temp at 80 degree by going about 55mph. Is coolant temp too low for my car? should I changed it back to 180 thermostat w/o tapping holes on it?
thanks in advance!
racerkan
Am located at Northern CA, just overhauled my cooling system on my 30k miles C5Z06 by replacing the upper and lower hoses, 160 thermostat (w/ 3 small 3/16 holes tapped) and used all distilled water w/ 2 bottles Redline water wetter. I also cleaned up all debris on AC Condense and Radiator. Now coolant temp dropped to 172 w/ outside temp at 80 degree by going about 55mph. Is coolant temp too low for my car? should I changed it back to 180 thermostat w/o tapping holes on it?
thanks in advance!
racerkan
Instructor
Joined: Mar 2020
Posts: 113
Likes: 28
Oil temp is really more important than coolant temp. 165-175 is a little chilly, as these engines seem to prefer being in the 195-205 range or even a little warmer. What concerns me is that with coolant temps that low, your oil is probably not getting warm enough. It needs to get to ~190 or above to steam out any moisture that may have gotten into it. That prevents sludge build up, among other ugly things that rob performance and create early engine cancers. Next time you drive it, check your oil temp. If it's not getting into the 180s and higher, I'd definitely consider going back to the stock thermostat. Consider this, if it's that cool now, what is it going to do this winter when you want to use the heater?
Melting Slicks
Joined: Sep 2006
Posts: 2,728
Likes: 142
From: Iowa
Why is it perfect for track use? Your coolant temp will ALWAYS be significantly higher than that during sessions. I'd imagine it's running wide open the entire session no matter which one you choose.
Last edited by Quickshift_C5; Jul 22, 2020 at 03:58 PM.
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 0
True, think air flow is more important. I once built a aluminum tunnel in front of my BMW race car's radiator similar to our c5, it take care the overheat problem and coolant temp decrease by at least 15 degree.