C5 water temp fluctuates
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Joined: Sep 2009
Posts: 73
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From: Jacksonville Florida
C5 water temp fluctuates
I have a 2000.
Under normal operation the engine temp sits around 200. After about 45 minutes of city driving Ive noticed while sitting at idle the temp rises to 220 then continues up to around 240 for about a minute or two then drops back to 220. It will do this continuously until I begin driving again and the temp lowers back to 200. Radiator is full. Is this normal? Does anyone know what may be happening? Bad thermostat?
Carman
Under normal operation the engine temp sits around 200. After about 45 minutes of city driving Ive noticed while sitting at idle the temp rises to 220 then continues up to around 240 for about a minute or two then drops back to 220. It will do this continuously until I begin driving again and the temp lowers back to 200. Radiator is full. Is this normal? Does anyone know what may be happening? Bad thermostat?
Carman
Melting Slicks
Joined: Sep 2011
Posts: 2,258
Likes: 543
From: Appleton WI
You are observing your fans in action. There is nothing wrong with your car. When you're in traffic the fans have to pull air through the radiator. They cycle on and off. Hence the 220 to 240 back to 220. When you're driving, you're forcing air through the radiator at a constant rate and therefore you get better cooling.
Drifting
Joined: Oct 2011
Posts: 1,872
Likes: 333
From: Olmsted Falls Ohio
St. Jude Donor '12 thru '24
I have a 2000.
Under normal operation the engine temp sits around 200. After about 45 minutes of city driving Ive noticed while sitting at idle the temp rises to 220 then continues up to around 240 for about a minute or two then drops back to 220. It will do this continuously until I begin driving again and the temp lowers back to 200. Radiator is full. Is this normal? Does anyone know what may be happening? Bad thermostat?
Carman
Under normal operation the engine temp sits around 200. After about 45 minutes of city driving Ive noticed while sitting at idle the temp rises to 220 then continues up to around 240 for about a minute or two then drops back to 220. It will do this continuously until I begin driving again and the temp lowers back to 200. Radiator is full. Is this normal? Does anyone know what may be happening? Bad thermostat?
Carman
The first fan comes on when the coolant temp reaches 226, and stays on until the coolant temp drops to 217. If the temp continues to climb above 226, it will eventually reach a point where additional fan activity will kick in and pull more air through the radiator.
You can prove this for yourself by starting the car and getting it up to temperature. Set the water temp into the DIC, while sitting at idle, pop the hood, get out of the car and wait for the fan to come on which should be as the temp hits 226. Wait for the fan to go off which should be at 217 on the DIC. While sitting at idle, this cycle will repeat itself over and over. If these are the actions you see, your car is functioning correctly.
Racer
Joined: Mar 2002
Posts: 317
Likes: 0
From: Missoula Mt
I'm going to have to check this also. The first day I bought my Z a couple months ago, I took a friend out for a ride in Tucson. I wasn't paying attention to the coolant temp, and when we got back to his house antifreeze was pouring on the ground. I started the car back up and turned on the cool-it to cool the car down, it seemed to me that it was above 240 at the time. Since then I have been hitting the cool-it button if it got to 230 or so to get it back down to 200. Something must be wrong with mine if I heat up enough to have coolant overflowing.
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
I'm going to have to check this also. The first day I bought my Z a couple months ago, I took a friend out for a ride in Tucson. I wasn't paying attention to the coolant temp, and when we got back to his house antifreeze was pouring on the ground. I started the car back up and turned on the cool-it to cool the car down, it seemed to me that it was above 240 at the time. Since then I have been hitting the cool-it button if it got to 230 or so to get it back down to 200. Something must be wrong with mine if I heat up enough to have coolant overflowing.
What "cool-it" button? A stock C5 has no such thing...
Racer
Joined: Mar 2002
Posts: 317
Likes: 0
From: Missoula Mt
Race Director
Joined: Jan 2008
Posts: 16,028
Likes: 170
From: oregon
when was the radiator changed? on a 2000 you're going to have a TON of debris and scaling present. 10 years imo is max life for a radiator unless it's oversize. cooling efficiency starts to drop. the c5, like the c4 is a vacuum cleaner that sucks up sand and everything else into the fins
in 90deg weather it should never go over 232-234 before the fans go into high speed. this is with the AC off
you can also force the fans on by using the AC which should keep the car under 220 even on the hottest of days if your cooling system is working properly
in 90deg weather it should never go over 232-234 before the fans go into high speed. this is with the AC off
you can also force the fans on by using the AC which should keep the car under 220 even on the hottest of days if your cooling system is working properly
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Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
Something has been hacked on your car because the fans should come on by themselves as it gets hotter so you don't have to monitor it and manually switch them on.