C5 Radiator Flush
Thread Starter
8th Gear
Joined: Nov 2008
Posts: 8
Likes: 0
From: Richmond Virginia
C5 Radiator Flush
Attempted to flush out my C5 for first time yesterday, but all I seemed to have accomplished was to drain and re-fill my coolant reservior. To completely drain the vehicle, must the system be "broken" with removal of the bottom radiator hose?
Additionally, should I even have flushed the system due to the fact that the car only has 6k miles? Does the coolant break-down after 5 years? I made that interpretation based on the "100,000 miles or 5 years, whichever comes first" statement in the owner's manual?
And lastly, what are the dangers of an air lock after flushing the system? Common problem in Vettes?
As my user name suggests, when it come to Corvettes, I really am "Just Learnin' "
THANKS for any and all help!
Additionally, should I even have flushed the system due to the fact that the car only has 6k miles? Does the coolant break-down after 5 years? I made that interpretation based on the "100,000 miles or 5 years, whichever comes first" statement in the owner's manual?
And lastly, what are the dangers of an air lock after flushing the system? Common problem in Vettes?
As my user name suggests, when it come to Corvettes, I really am "Just Learnin' "
THANKS for any and all help!
Drifting
Joined: May 2006
Posts: 1,616
Likes: 1
From: Minnesota
Did you open the drain plug at the bottom of the radiator? You won't be able to get all of it out but you should get most of it out that way. As for the need I would say you were safe not doing it but I think it's a good thing to do every 5 years regardless of miles.
Thread Starter
8th Gear
Joined: Nov 2008
Posts: 8
Likes: 0
From: Richmond Virginia
First a couple of answers to your questions. I had no issues with air locks in the system by using the GM procedure. (Unlike my C4 which was damn near impossible to get the air locks out of) Flushing the old stuff may not be necessary if it still looked good as you drained it out, but is a good idea IMHO to avoid problems down the road. Not removing the lower radiator hose seems to leave about 1-2 Qts more in the system than if you remove it in my experience below.
I just did the same thing with my 04 this past week. I was upgrading to a Dewitts radiator and though the car has only just under 10K miles in the 5 years since it was built (10/29/03) I wanted to get as much of the old red stuff out as possible. When I removed the radiator I was able to get only about 10 of the 12.6 quarts out (actually took the time to capture and measure it). Once the new rad was in I decided to use a real PIA procedure to dilute the remaining 2 plus Qts still in the block and heater. I filled the system with deionized water then went through the GM procedure to remove the air from the system and then let it cool. I drained all I could without removing the lower hose again and got about 9 qts out. Then I repeated the process 3 more times. At the end of the 4th iteration the water captured was nearly totally clear. I then added 2 plus gallons of undiluted antifreeze. With the Dewitts radiator I now have an additional gallon of capacity in just the radiator so I figure 2 plus gallons with what was left of the deionized water in the block and heater gives me about a 50-50 mix. In a week or so after I get several hundred miles on it I will test the solution to see where it actually set.
I just did the same thing with my 04 this past week. I was upgrading to a Dewitts radiator and though the car has only just under 10K miles in the 5 years since it was built (10/29/03) I wanted to get as much of the old red stuff out as possible. When I removed the radiator I was able to get only about 10 of the 12.6 quarts out (actually took the time to capture and measure it). Once the new rad was in I decided to use a real PIA procedure to dilute the remaining 2 plus Qts still in the block and heater. I filled the system with deionized water then went through the GM procedure to remove the air from the system and then let it cool. I drained all I could without removing the lower hose again and got about 9 qts out. Then I repeated the process 3 more times. At the end of the 4th iteration the water captured was nearly totally clear. I then added 2 plus gallons of undiluted antifreeze. With the Dewitts radiator I now have an additional gallon of capacity in just the radiator so I figure 2 plus gallons with what was left of the deionized water in the block and heater gives me about a 50-50 mix. In a week or so after I get several hundred miles on it I will test the solution to see where it actually set.
Where can I find the "GM procedure" for flushing the system?
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
You should be able to get about 2 gallons out by just draining the radiator. I do not let my antifreeze go over about 2 years, so I do not worry about flushing the whole system. I just drain out what I can and add back a fresh 50/50 mixture of Dexcool and distilled water.
