Removing old Antifreeze by dilution

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There are a lot of ways to change coolant but systems are a little harder to flush with no radiator cap and a reluctance of some folks to disconnect hoses to do a full flush.

One way is through dilution which I recently used. This was a 2005 Ford Taurus OHV with 12 quart ( 3 gallon system.)

Mine still has a drain valve on the rad, so I did not have to disconnect a hose. However I did remove the plastic wind deflector from underneath the radiator, a job made easy with my Dewalt impact driver, in order to access the valve.

I drained the rad and got back two gallons, including the pressure tank which by itself holds a half gallon. On this car the P tank is active and takes a side stream of coolant from the engine. The fluid is hot to the touch after a drive.

So, with two gallons back that meant there was still a gallon in the engine. I added two gallons of distilled water through the coolant tank and took it for drive to run errands, with the heat on. I got home, let it cool and drained the fluid. I then added two gallons of distilled water again and did the same procedure. I drained it, confirmed it was mostly water with very little of the original coolant, then poured in 1 gallon of 100% concentrated coolant and and 1 gallon of 50-50 distilled water and coolant. This would have brought me close to fifty fifty coolant and water. I have attached three photos of the coolant freezing point with my density based coolant tester. The first photo indicates the freezing temp is off the scale and working with a density chart that would indicate about a 65 to 70 % coolant concentration. This common up here in Canada. After diluting with two gallons of distilled water, it showed a freezing point of -10 F which indicates a concentration of about 25%. Finally, after diluting it a 2nd time the freezing point was off the scale in the opposite direction indicating mostly water. By the way, the math seemed to work but I don't want to bore anyone. Enjoy the photos. This posting was brought to you by Prestone with Cor-Guard.
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Snaggle you basically did what I call a distilled flush series. You do distilled water radiator d&fs until water runs clear or close. Then using a full strength AF add half/50% system capacity top with distilled, 6 quarts AF this case. Should be good to -34F. Want 60% AF multiple that by capacity, 7.2qts AF this case. Yes can check with AF tester but should be real close to what AF temp capacity conversion charts show without one. As distilled water is inexpensive, other than time involved number of d&fs not an issue.

Here's a common AF chart courtesy member Warstud and Peak AF
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60% AF good to -62F

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Originally Posted by 53' Stude
Snagglefoot: your old coolant looks like it was a good time to do a flush
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Thanks for the post and pictures


I agree. The age was unknown when I bought it used. I've noticed yellow and red ( Dexcool) coolant both fade with age.
 
By the way, some folks just drain once and re-fill with mixed coolant. OK as a poor-boy solution but depending on the design, you might still have 20% to 30% old coolant. What's the harm? You'd still have the freeze protection but would be missing out on some additional corrosion inhibitor. YRMV.
 
I REALLY over thought my coolant flush last summer....First thing i did was drain it down, remove thermostat, fill with RO water(our well is way too sulphur/iron/etc), drive to the store, refill the RO Jugs(25 cents/gal, 2 gal @ a time), and repeat, keeping in mind I only get 50% of it out each time, so do the math, get it down to.where there was maybe 1/2 cup of the original stuff still in the system. drove on that for a few days, then another couple D&F's with Distilled, install new thermostat, top off system with concentrate(half the system is all water) and Bob's you're uncle.
 
I did what you did with my cutlass ciera a while back. The last water changes were still tinged brown, like iced tea. Car was overdue and happier afterwards.
 
Originally Posted by eljefino
I did what you did with my cutlass ciera a while back. The last water changes were still tinged brown, like iced tea. Car was overdue and happier afterwards.


I find that once the coolant is gone and you have only fresh water it's impossible to have it crystal clean without rust inhibitors. I saw the same problem after 8 hrs allowing the engine to cool overnight. I guess if you had an aluminum blocks and heads it wouldn't be a problem. One way to avoid it, is to throw in a small amount of fresh coolant with each water sweep.
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Originally Posted by Sayjac
Snaggle you basically did what I call a distilled flush series. You do distilled water radiator d&fs until water runs clear or close. ...
I used to do a variation of that tedious routine, but worried that running that long on plain water might damage the water pump seal. Antifreeze supposedly contains (or acts as) seal lubricant. Any expert opinions on that issue?
 
Originally Posted by CR94
Originally Posted by Sayjac
Snaggle you basically did what I call a distilled flush series. You do distilled water radiator d&fs until water runs clear or close. ...
I used to do a variation of that tedious routine, but worried that running that long on plain water might damage the water pump seal. Antifreeze supposedly contains (or acts as) seal lubricant. Any expert opinions on that issue?


30 minutes of running with water?
 
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Originally Posted by FordCapriDriver
What inhibitor package does CorGuard use?


Appears to be a P-OAT. SDS shows 2-Ethyl Hexanoic Acid and the latest PQIA analysis shows Phosphate. There are most likely other corrosion inhibitors as well. It should offer better protection than conventional Dex-Cool or clones since the phosphate will provide fast acting corrosion protection. It seems fine to me, though I always thought the 2-EHA concerns were way overblown.
 
From what i've been able to gather the concerns over 2-Eha are true, it corrodes Solder ( specially High lead ) unless there is also Molybdate present.
Rubber components not designed to deal with it also suffer.

One coolant that is very interesting is G64, it's a PSi-OAT, in other words an OAT coolant with Phosphates and Silicates, which may or may not have 2-Eha depending on the particular brand you buy ( look for it i the SDS if you want to know if a particular coolant has it or not ), i made a thread on it not long ago and apparently it's sold in the U.S as Zerex Original Green which is interesting.

Sadly it's not available here in Spain, if it were i would be using it, for the meantime i am using G40 Si-OAT which in my opinion is better than P-OAT, Silicates offer much better protection to Aluminium than Phosphates, it is true that Phosphates provide Cast Iron protection but Cast Iron is not a fussy metal at all and it is protected by the Organic Acid inhibitors more than adequately.
 
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Originally Posted by Snagglefoot
Originally Posted by CR94
I used to do a variation of that tedious routine, but worried that running that long on plain water might damage the water pump seal. Antifreeze supposedly contains (or acts as) seal lubricant. Any expert opinions on that issue?
30 minutes of running with water?
Likely longer than that overall, by the time you warm the engine enough for the thermostat to open, and do so several times with cold water.
 
Originally Posted by FordCapriDriver
From what i've been able to gather the concerns over 2-Eha are true, it corrodes Solder ( specially High lead ) unless there is also Molybdate present.
Rubber components not designed to deal with it also suffer.

One coolant that is very interesting is G64, it's a PSi-OAT, in other words an OAT coolant with Phosphates and Silicates, which may or may not have 2-Eha depending on the particular brand you buy ( look for it i the SDS if you want to know if a particular coolant has it or not ), i made a thread on it not long ago and apparently it's sold in the U.S as Zerex Original Green which is interesting.

Sadly it's not available here in Spain, if it were i would be using it, for the meantime i am using G40 Si-OAT which in my opinion is better than P-OAT, Silicates offer much better protection to Aluminium than Phosphates, it is true that Phosphates provide Cast Iron protection but Cast Iron is not a fussy metal at all and it is protected by the Organic Acid inhibitors more than adequately.



You should phone them up and discuss their patents, and their claim on the bottle that they have 5 times more effective engine protection. Somehow I seriously doubt Prestone is running chemicals that damage solder or that their product damages any engine's rubber especially with their claim it is a mult-vehicle product. Anyway, I have used Prestone branded anti-freeze for years and have never had any corrosion in any of my engines or solder or rubber failures, so I am good to go. Thanks for your posting.
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