Antifreeze changed.. - PeachParts Mercedes-Benz Forum

wolf_walker · #1 01-06-2004, 08:17 PM

I love it when something works out RIGHT for a change.

Replaced the ORANGE coolant PO had in the 83 with G-05 and distilled water. Had planned on a standard flush and clean with zerex off the shelf cleaner, but this car has to have the cleanist cooling system I've ever seen on a two decade old car. Ever.
Every hose I pulled off, every opening I could get open and stick my finger in, was clean, no crud, no scale, no oil, nothing. Nada. I couldnt believe it. So I just drained the radiator, drained the block(got drenched), put in a new T-stat, new radiator cap, and filled it back up. No air pocket problems at all, temp is up to where I thought it should be, just slightly above 80C in normal driving.

JimSmith · #2 01-06-2004, 08:29 PM

Congrats on getting a messy job done, and for finding a car that well cared for. Good luck, Jim

wolf_walker · #3 01-07-2004, 08:35 AM

The distilled water is mostly old habit. We have a well here, which I'm sure is full of *stuff* I'd rather not have in my cooling system.

Do people really not bother with distilled water any longer? Everyone preached about it when I was in tech school and growing ut, etc..?

Kestas · #4 01-07-2004, 10:22 AM

People get passionate both ways (distilled or tap) for mixing the coolant. I vote for distilled.

wolf_walker · #5 01-07-2004, 02:24 PM

Oh, one of *those* kind of debates.. I see..

DieselAddict · #6 01-07-2004, 06:15 PM

I'm a firm believer in distilled water because tap water typically has a lot of minerals. These will precipitate in your cooling system and restrict flow.

DieselAddict · #7 01-07-2004, 07:35 PM

That doesn't make sense to me. Firstly ions are atoms already dissolved in a solution so I don't understand how water can strip ions from metal. Maybe you meant atoms, not ions. I don't know if that's true, but even if it is I don't see how tap water would not strip metal while distilled water would. Why would they behave so differently? Besides, you don't put pure distilled water in your cooling system. You mix it with good antifreeze which will prevent corrosion.

P.E.Haiges · #8 01-07-2004, 10:53 PM

If you use Evans waterless coolant, you don't have to worry about all those ions and contaminents in the water.

P E H

ericnguyen · #9 01-08-2004, 12:46 AM

dieseldiehard: "Atomic core" should be "atomic nucleus".

P.E.Haiges: Evans waterless coolant requires a near complete removal of all water in the cooling system. Doing this on an old Mercedes would be quite a big chore and may be very time-consuming (several days to dry with a hair dryer etc..)

In pure water, the following 2 reactions constantly occur in both directions, and they are in an equilibrium state.

1) H20 <-> H(+) + OH(-)

2) H2O + H20 < -> H3O(+) + OH(-)

H(+) is a positive hydrogen ion, OH(-) is a negative hydroxide ion, and H3O(+) is a positive hydronium ion.

In tap water, the existence of minerals (and salts) such as NaCl, KCl, Na2CO3, NaHCO3, NaNO3, CaCO3, MgCO3 etc... means that there is an abundance of other ions such as Na(+), Ca(2+), Mg(2+), Cl(-), CO3(-2), NO3(-) .... besides the above-mentioned water-derived ions.

We generally have 3 different terms for "purified water".

1) De-mineralized water (pure), also called "softened water"

2) Distilled water (purer)

3) Deionized water (purest)

Deionized water, de-mineralized water, distilled water are called "purified water" because the extra minerals and salt ions are removed thanks to chemical precipitation/resin ion exchanges, and steam distillation/condensation (for distilled water only). So most of the extra ions (besides the water-derived ions) are extracted, but the water-derived ions (hydrogen ions, hydroxide ions, hydronium ions) are always there, because that's how water molecules and their ions exist in constant equilibrium.

In a nutshell, the strength of an acid is represented by the concentration of hydrogen ions H(+) it can create, and the strength of a base (alkaline) by the concentration of hydroxide ions (OH-).

The pH of a solution is calculated from the formula: pH = -log[H+]
Remember that this "log" stands for decimal logarithm (base 10), not the natural (or Napierian) logarithm (base e=2.7182818..)

For the purest water, the concentrations of H(+), OH(-), H3O(+)
are equal, so [H(+)] = [OH(-)] = [H3O(+)] = 10^(-7). Therefore, the pH of purest water is:

pH = -log[H+] = -log(10^-7) = - (-7)log(10) = 7x1 = 7

For real acids, [H+] is definitely greater than 10^(-7), i.e. it should
be 10^(-n) where n < 7. This means that the pH of an acid is always less than 7:

pH = -log[H+] = -log(10^-n) = -(-n)log(10) = nx1 = n < 7

For real bases, [H+] is less than 10^(-7), i.e. it should be 10^(-m) where m > 7. This means that the pH of an acid is always greater than 7:

pH = -log[H+] = -log(10^-m) = -(-m)log(10) = mx1 = m > 7

For tap water (H+, OH-, H30+, Na+, Cl-, NO3-, etc....), the mineral or salt ions react with water-derived H+, H30(+) ions and prevent them from acting like an acid (which are very corrosive to metals). De-mineralized/deionized/distilled water don't have or have very little mineral/salt ions, so the water-derived H+, H3O(+) are free to attack metal atoms by sucking the low valence electrons from the outer orbital shell of metal atoms (note that H+ and H3O+ have positive charge and electrons have negative charge, so they have high affinity for each other)

The chemical ingredients in the antifreeze coolants such as Dexcool and Mercedes/Zerex G-05 produce lots of other ions that help neutralize the effect of H+, H3O(+) in de mineralized/deionized/distiller water (purified water), so it is OK to mix purified water with antifreeze without any problem. Keep in mind that you MUST use at least 50% antifreeze in your antifreeze/water solution (but less than 70%)! If you follow the proper mixture ratio, purified water is always better than tap water. No minerals/salts = No scaling/deposits/blocking...

HOWEVER, if you use too little antifreeze or just simply use purified water in your cooling system (such as in racing cars), you will kill your engine/radiator IN NO TIME FLAT because of the attacking H+, H3O+ from purified water.

Eric

DieselAddict · #10 01-08-2004, 12:43 PM

Right on, Eric. You certainly refreshed my memory on chemistry.

So in the end, I was right. As long as the corrosive distilled water is mixed sufficiently with antifreeze, there's no problem, and it's better to use distilled water because it won't lead to mineral buildup.

blacksmoke · #11 01-08-2004, 01:28 PM

yes, what eric said. besides, the only thing that the distilled water 'might' strip -or rather share ions with- are those elements or compounds that have a covalent bond, that's 'not' going to me metals.

wolf_walker · #12 01-08-2004, 03:20 PM

Is it some cosmic law that EVERYTHING has to get more complicated as time goes on? ~sigh~

I know one thing only, I've changed a LOT of coolant using 50/50 antifreeze and distilled water and put litteraly millions of miles personaly on the vehicles and seen no ill effects. This is interisting and I don't have the chemistry background to argue, but it can't be that big a deal.

If not distilled, how about purafied drinking water? I see that for sale as well.

JimSmith · #13 01-08-2004, 03:37 PM

wolf_walker,

The argument really should have ended, and it was sort of settled in your favor by eric, but if you keep it going, that could change as someone will find a story that says someone's car was dissolved by distilled water...... Distilled water is fine when mixed 50/50 with a suitable antifreeze. I use the stuff my dehumidifier gets out of the air in my basement. Not demineralized or deionized, but not full of the stuff that makes my well water taste so good either. Good luck, Jim