New C5 owner, engine temp issues
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Joined: Mar 2012
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From: Austin Texas
New C5 owner, engine temp issues
I have a 2003 C5 that I just bought a month or so ago. It was running hot (getting up to 240ish when it was 45 degrees out?) but would also drop down to 200ish. I replaced the thermostat, fluild (regular drain, not a full flush), and the temp sensor. It seemed to keep the temp down a lot however now it's getting hotter (I'm in Austin, TX and now probably in the 80's). This morning it got up to 244 but then within 2 minutes, down to 204. So it seems like the fans are the issue. How do I diagnose? I blew out the radiator with compressed air and a brush.
Thanks!
Thanks!
Melting Slicks
Joined: Jan 2009
Posts: 2,127
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From: Easley/Anderson South Carolina
You need to see what the ecu has as far as the turn on and off temps for both fans. It seems maybe that car was from a cooler temp area and the fans were set to turn on at a warmer temp.
Or you have a bad fan? I doubt that tho as you said the temp would decrease.
Or you have a bad fan? I doubt that tho as you said the temp would decrease.
Race Director
Joined: Jan 2006
Posts: 10,554
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From: Not on either liberal coast.
Possibility of air pockets still in the system? Reservoir cap? Possibility there's still debris in the upper areas of the a/c condenser or radiator blocking air flow?
Remove the top radiator core support ("caution fan") to expose more of the cores for thorough cleaning with air or water to remove debris.
Remove the top radiator core support ("caution fan") to expose more of the cores for thorough cleaning with air or water to remove debris.
Last edited by hotwheels57; Mar 26, 2012 at 04:13 PM.
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Joined: Mar 2012
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From: Austin Texas
If I have air, how do I get rid of it? See below. I don't think it's a "physical problem" because it will come down in temp quickly. I don't think that would mean air is an issue.
On the ECU, how do I know what the temp settings are? Given that it suddenly seems to drop from let's say 240 to 210 in less than a minute, it seems to be a "fan coming on" issue. How do I check and fix that?
On the ECU, how do I know what the temp settings are? Given that it suddenly seems to drop from let's say 240 to 210 in less than a minute, it seems to be a "fan coming on" issue. How do I check and fix that?
Race Director
Joined: Jan 2006
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From: Not on either liberal coast.
You can find any number of past threads on the burping procedure in C5 Tech. Use search or search this forum (in the red banner). Use keywords "c5 coolant system burping procedure" or similar.
Here's just one...
http://forums.corvetteforum.com/c5-t...-radiator.html
Raise the car in the front to aid in releasing the air pockets. Follow the procedure in the thread above. A water surfactant (WATER WETTER) will aid in breaking surface tension of the coolant within the cooling system, also.
The symptoms of an air pocket may be just what you're describing with erratic cooling. Air pockets (steam) don't cool the motor well.
Here's just one...
http://forums.corvetteforum.com/c5-t...-radiator.html
Raise the car in the front to aid in releasing the air pockets. Follow the procedure in the thread above. A water surfactant (WATER WETTER) will aid in breaking surface tension of the coolant within the cooling system, also.
The symptoms of an air pocket may be just what you're describing with erratic cooling. Air pockets (steam) don't cool the motor well.
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From: Blue Ridge Georgia
Start w/ a cold engine
Remove rad. cap
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Start engine
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Top off
Remove rad. cap
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Start engine
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Top off
Quick spikes and drops tend to be air or thermostat related in my experience. 
Drifting
Joined: Jan 2010
Posts: 1,447
Likes: 1
From: Katy TX
Start w/ a cold engine
Remove rad. cap
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Start engine
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Top off
Remove rad. cap
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Start engine
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Top off
Thread Starter
Advanced
Joined: Mar 2012
Posts: 72
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From: Austin Texas
I just bought the car in the past month or so and changed the coolant, thermostat, and temp sensor. That's it. I have talked to the previous owner a lot and don't think anything else was done recently or don't believe there are any other issues that would relate (that he knew about).
How do you bleed from the heads??
How do you bleed from the heads??
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St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
Drifting
Joined: Jan 2010
Posts: 1,447
Likes: 1
From: Katy TX
Thread Starter
Advanced
Joined: Mar 2012
Posts: 72
Likes: 0
From: Austin Texas
Here's an update:
Vette was getting hot. Like 240.
I replaced the thermo, temp sensor, and coolant. Consistently when first driving it would get to 240-243. Scary. Then while driving it was mostly 220-230, sometimes a little lower.
followed the:
Start w/ a cold engine
Remove rad. cap
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Start engine
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Top off
I followed that. With our type systems where you only have the overflow tank and nothing on the radiator, that overflow cap was not hot when the engine was at 210.
I did all that and NOW, when it would get to 240ish, now I'm at 195 and it ranges from about 195-205.
I read so many posts about washing the radiators, etc, but it was this simple! thanks!!
Vette was getting hot. Like 240.
I replaced the thermo, temp sensor, and coolant. Consistently when first driving it would get to 240-243. Scary. Then while driving it was mostly 220-230, sometimes a little lower.
followed the:
Start w/ a cold engine
Remove rad. cap
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Start engine
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Top off
I followed that. With our type systems where you only have the overflow tank and nothing on the radiator, that overflow cap was not hot when the engine was at 210.
I did all that and NOW, when it would get to 240ish, now I'm at 195 and it ranges from about 195-205.
I read so many posts about washing the radiators, etc, but it was this simple! thanks!!
