Coolant refill procedure
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
I just fill it up, burp out what I can by hand, then let it idle for 20-30 mins with the overflow cap off... basically let the fans cycle a few times and burp the hoses by hand during this process then top off as needed and replace the cap
Thread Starter
Racer
Joined: Dec 2004
Posts: 319
Likes: 5
From: Murphy NC
Drifting
Joined: Apr 2007
Posts: 1,517
Likes: 159
From: Lafayette Louisiana
My procedure is
Drain coolant.
Fill with Distilled water
Go for a drive heater on max
Drain coolant
Fill with Distilled water
Go for a drive heater on max
Drain coolant
Put in a Gallon and a half of Preston Concentrate
Fill with Distilled water
Go for a drive.
Check and fill with Distilled water if needed.
The question, what do you do with the old coolant?
Drain coolant.
Fill with Distilled water
Go for a drive heater on max
Drain coolant
Fill with Distilled water
Go for a drive heater on max
Drain coolant
Put in a Gallon and a half of Preston Concentrate
Fill with Distilled water
Go for a drive.
Check and fill with Distilled water if needed.
The question, what do you do with the old coolant?
Last edited by UM Rebel; Jan 17, 2018 at 03:47 AM.
Pro
Joined: Feb 2013
Posts: 535
Likes: 92
From: Raleigh NC
Anybody used one of the vacuum filling tools? The videos I've watched make it look awesome. Basically the tool pulls a vacuum on your cooling system (like you would an AC system before charging), and then that vacuum pulls the coolant in. Which means no air pockets in the system to burp out.
Here's an example. A little pricey if you're just doing one car, but over a lifetime of vehicles could be worthwhile.
http://amzn.to/2DioZv3
Here's an example. A little pricey if you're just doing one car, but over a lifetime of vehicles could be worthwhile.
http://amzn.to/2DioZv3
Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl
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Drifting
Joined: May 2008
Posts: 1,695
Likes: 490
From: Denver, NC
My C4 had bleeder screws. Haven't done my C5 yet. Reading this I'm kind of surprised they went away. I also usually look for a sensor that's higher that can function as a bleeder. Luckily the PO had it done once - I have some time to familiarize myself with the car.
Last edited by Ed Ramberger; Jan 17, 2018 at 11:15 AM.
Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,820
From: Charlotte, NC (formerly Endicott, NY)
I just drained the coolant, filled with plain drinkable water (all that GM recommends) and is easy to get from your garden hose, ran engine, drained, filled, ran engine, drained again and repeated until drained water was clear. That got rid of all the old coolant. At that point I would replace hoses and fill with the proper amount of coolant (6 quarts I believe) and top off with plain drinkable water. Then drive car, let cool down and drive again. Let it cool down again and check coolant level. If low then top off with plain drinkable water.
No need to use Distilled Water, Deionized water. If it is safe enough for you to drink it is OK in the cooling system per GM recommendations in its service manuals. If you use DexCool coolant that will get you 5 years coolant life before you need to touch it again.
Bill
No need to use Distilled Water, Deionized water. If it is safe enough for you to drink it is OK in the cooling system per GM recommendations in its service manuals. If you use DexCool coolant that will get you 5 years coolant life before you need to touch it again.
Bill
Drifting
Joined: May 2008
Posts: 1,695
Likes: 490
From: Denver, NC
I just drained the coolant, filled with plain drinkable water (all that GM recommends) and is easy to get from your garden hose, ran engine, drained, filled, ran engine, drained again and repeated until drained water was clear. That got rid of all the old coolant. At that point I would replace hoses and fill with the proper amount of coolant (6 quarts I believe) and top off with plain drinkable water. Then drive car, let cool down and drive again. Let it cool down again and check coolant level. If low then top off with plain drinkable water.
No need to use Distilled Water, Deionized water. If it is safe enough for you to drink it is OK in the cooling system per GM recommendations in its service manuals. If you use DexCool coolant that will get you 5 years coolant life before you need to touch it again.
Bill
No need to use Distilled Water, Deionized water. If it is safe enough for you to drink it is OK in the cooling system per GM recommendations in its service manuals. If you use DexCool coolant that will get you 5 years coolant life before you need to touch it again.
Bill
NEVER use tap or hose water - always use deionized or distilled. The minerals found in tap water will contribute to electrolysis inside your engine slowly eating away at radiators, heater cores, head gaskets, etc...
This is one time where even if the FSM said it was ok, it's wrong. I worked for an OEM engine manufacturer for 14 years and we specified deionized or distilled because we knew the results of using tap water or drinking water with minerals in it. Also, from working at manufacturer level, I can tell you that FSMs are not infallible and do get published with errors and omissions from time to time.
Bill - I understand you followed the directions you found - just trying to help everyone out in the long term.
Last edited by Ed Ramberger; Jan 20, 2018 at 10:47 AM.
Drifting
Joined: Jun 2013
Posts: 1,965
Likes: 343
From: Shell Point (Crawfordville) Florida
You may be mistaking electrolysis for galvanic corrosion.
Galvanic corrosion is driven by the difference in corrosion potential (or electrical potential) between two metals in contact, immersed in an electrolyte, while electrolytic corrosion or electrolysis is driven by the external sources of EMF (ie, current) passing between them.
The minerals in the water may be what is making the antifreeze into an electrolyte so that it may conduct a current flow, (thereby leading to corrosion of the less noble metal), but there must be source of current for electrolysis to occur. There is no corrosion if all the metals are equal on the galvanic scale, immersed in an electrolyte or not.
As a practical matter, while distilled water is probably better, I don't think there's a great deal of harm with using clean drinkable tapwater, and there are no dire warnings against using it or consequences reported from using it, in the millions of cars on the road, especially with all the anti-corrosion additives in all the antifreezes on the market used today.
Galvanic corrosion is driven by the difference in corrosion potential (or electrical potential) between two metals in contact, immersed in an electrolyte, while electrolytic corrosion or electrolysis is driven by the external sources of EMF (ie, current) passing between them.
The minerals in the water may be what is making the antifreeze into an electrolyte so that it may conduct a current flow, (thereby leading to corrosion of the less noble metal), but there must be source of current for electrolysis to occur. There is no corrosion if all the metals are equal on the galvanic scale, immersed in an electrolyte or not.
As a practical matter, while distilled water is probably better, I don't think there's a great deal of harm with using clean drinkable tapwater, and there are no dire warnings against using it or consequences reported from using it, in the millions of cars on the road, especially with all the anti-corrosion additives in all the antifreezes on the market used today.
Last edited by mrlmd; Jan 20, 2018 at 04:07 PM.
Drifting
Joined: May 2008
Posts: 1,695
Likes: 490
From: Denver, NC
You may be mistaking electrolysis for galvanic corrosion.
Galvanic corrosion is driven by the difference in corrosion potential (or electrical potential) between two metals in contact, immersed in an electrolyte, while electrolytic corrosion or electrolysis is driven by the external sources of EMF (ie, current) passing between them.
The minerals in the water may be what is making the antifreeze into an electrolyte so that it may conduct a current flow, (thereby leading to corrosion of the less noble metal), but there must be source of current for electrolysis to occur. There is no corrosion if all the metals are equal on the galvanic scale, immersed in an electrolyte or not.
As a practical matter, while distilled water is probably better, I don't think there's a great deal of harm with using clean drinkable tapwater, and there are no dire warnings against using it or consequences reported from using it, in the millions of cars on the road, especially with all the anti-corrosion additives in all the antifreezes on the market used today.
Galvanic corrosion is driven by the difference in corrosion potential (or electrical potential) between two metals in contact, immersed in an electrolyte, while electrolytic corrosion or electrolysis is driven by the external sources of EMF (ie, current) passing between them.
The minerals in the water may be what is making the antifreeze into an electrolyte so that it may conduct a current flow, (thereby leading to corrosion of the less noble metal), but there must be source of current for electrolysis to occur. There is no corrosion if all the metals are equal on the galvanic scale, immersed in an electrolyte or not.
As a practical matter, while distilled water is probably better, I don't think there's a great deal of harm with using clean drinkable tapwater, and there are no dire warnings against using it or consequences reported from using it, in the millions of cars on the road, especially with all the anti-corrosion additives in all the antifreezes on the market used today.
The water where I lived in WI was so hard you would have to have been nuts to add it to a radiator. Note the author works for a company that specializes in cooling system.
http://www.hotrod.com/articles/keep-...-electrolysis/
Intermediate
Joined: May 2002
Posts: 44
Likes: 2
From: Fayetteville NC
Recommended procedure removing any air after changing coolant:
1. Close drain valve after old fluid is out.
2. Fill via the surge tank (50:50)
3. Start engine and idle for 1 minute before closing surge tank.
4. Install surge tank cap.
5. Cycle from idle for 30 seconds, to 3000 rpm for 30 seconds, and continue this until coolant temp is 210 F (99 C).
6. Turn off engine, take off surge cap, restart engine, idle for 1 minute.
7. Add coolant till 1/2 inch above cold full mark, then put the cap back on.
8. Cycle from idle to 3000 rpm just like step 5 until it reaches the same temp.
9. Turn off engine, add coolant till 1/2 inch above cold full mark, put cap back on.
10. Done.
1. Close drain valve after old fluid is out.
2. Fill via the surge tank (50:50)
3. Start engine and idle for 1 minute before closing surge tank.
4. Install surge tank cap.
5. Cycle from idle for 30 seconds, to 3000 rpm for 30 seconds, and continue this until coolant temp is 210 F (99 C).
6. Turn off engine, take off surge cap, restart engine, idle for 1 minute.
7. Add coolant till 1/2 inch above cold full mark, then put the cap back on.
8. Cycle from idle to 3000 rpm just like step 5 until it reaches the same temp.
9. Turn off engine, add coolant till 1/2 inch above cold full mark, put cap back on.
10. Done.
Thread Starter
Racer
Joined: Dec 2004
Posts: 319
Likes: 5
From: Murphy NC
Recommended procedure removing any air after changing coolant:
1. Close drain valve after old fluid is out.
2. Fill via the surge tank (50:50)
3. Start engine and idle for 1 minute before closing surge tank.
4. Install surge tank cap.
5. Cycle from idle for 30 seconds, to 3000 rpm for 30 seconds, and continue this until coolant temp is 210 F (99 C).
6. Turn off engine, take off surge cap, restart engine, idle for 1 minute.
7. Add coolant till 1/2 inch above cold full mark, then put the cap back on.
8. Cycle from idle to 3000 rpm just like step 5 until it reaches the same temp.
9. Turn off engine, add coolant till 1/2 inch above cold full mark, put cap back on.
10. Done.
1. Close drain valve after old fluid is out.
2. Fill via the surge tank (50:50)
3. Start engine and idle for 1 minute before closing surge tank.
4. Install surge tank cap.
5. Cycle from idle for 30 seconds, to 3000 rpm for 30 seconds, and continue this until coolant temp is 210 F (99 C).
6. Turn off engine, take off surge cap, restart engine, idle for 1 minute.
7. Add coolant till 1/2 inch above cold full mark, then put the cap back on.
8. Cycle from idle to 3000 rpm just like step 5 until it reaches the same temp.
9. Turn off engine, add coolant till 1/2 inch above cold full mark, put cap back on.
10. Done.
Thanks guys!