motoman

The lab tested the original coolant contained in the 2009 C63 (29K miles). The car has only been serviced at home, and has taken about 2-3 cups of make-up coolant since new (MB 325.1 and distilled water, 50-50). Results are "critical" for calcium and total hardness (flush immediately). According to the lab this is due to the water (used by MB or dealer prior to purchase). The risk is scaling of the coolant system which can plug radiator or create hot spots where heat exchange is reduced.

This result is surprising after expecting a low pH (acidic)which could contribute to head bolt corrosion (pH is 7.9). The MB official service interval of "no coolant change" can be dangerous. In this case the MB antifreeze is not suspect. Also the mix ratio (57% anitfreeze) does not favor the the boiling point determined at 228F which is too close for comfort even though the dash gauge is steady at 197F (mostly). IMO boiling says oxygen bubbles going to work and pitting the headbolts. Tried to attach report, but still cannot (2nd request to administraor).

Edit: The low boil point kept gnawing...so I read the back of the MB anitfreeze bottle. ATMOSPHERE boil is 225F with 50-50- that must be what the test lab showed, but did not clarify. But MB says max 55% antifreeze and mine is 57%. With a 20 lb cap boil point goes to 275, much more appropriate,

Critter

Thanks Motoman, good information. Do you feel the addition of those additives to the coolant to reduce surface friction, like "Water Wetter" would reduce the oxygen bubble attacking the metal surfaces inside of the engine, notably the headbolts. Have it in both cars Will have to check PH in my Benzs and compare to my other cars.
Is your water in WA hard by any chance, with high levels of calcium? Meaning dealer additions or?

motoman

Critter, I did a lot of reading about coolants and a complex subject it is. Most of the in- depth is from diesel fleet users who have refined their needs,some of which may not apply to passenger cars e.g., coolant filters with supplemental additives. I have seen "water wetter" mentioned often, but I have no first hand experience. We are rural here and do use a salt filter or our well water, but with high rainfall the water probably tends acidic. What comes out of the Portland city taps is unknown. If MB did use tap water it is an extreme irony as I read that Euro manufacturers specifically developed their antifreeze to combat hard water (vs asian).

whoover

pH 7.9 is alkaline, not acidic.

whoover

57% is a tad high, but not outrageously so. The book calls for 50-55%. Also, our spec is 325.0. I don't think there's a 325.1 so that was probably just a typo.

The Pacific Northwest has some of the softest water in the country. It's a real mystery how you would wind up with so much calcium.

-Marlin-

Would you mind dumbing this down for me fellas? I have a simple mind. It's stirring with the problem you're trying to convey, but I could use a push.....?

Ingenieur

He said the results were surprising
He expected low/acidic pH
But it was actually 7.9 or higher/alkaline

The system operates under pressure
228 F is at std atm P
Probaby 50 deg higher under pressure
Edit: reread your post, you already saw that

Ingenieur

I think he was trying to determine if coolant chemistry might accelerate or contribute to head bolt failure

For reference potable water standards are typically 6.5 to 9 range
Most average 8 to 8.5

http://www.corrosionist.com/what_is_...osion_rate.htm
Basic info on corrosion rate
Constant 4 to 10
Rise sharply below 4
Decreases gradually above 10
And that is aerated water only
Coolant has inhibitors so will be lower

Corrosion imo has little effect on the head bolt failure mode
They simply used the wrong type of fastener for the application

whoover

Federal recommendation is pH between 6.5 and 8.5 for drinking water. 9.0 would be pretty alkaline. I manage a small volunteer-run water company and test our water monthly. pH is always between 7.5 and 7.8. This varies greatly by area, depending on water source (surface water, ground water, etc.). We worry mostly about bacterial contamination, then chlorine levels, then byproducts of disinfection (like haloacetic acids) and finally pH. Obviously, the harder your water the lower the pH.

Ingenieur

I have a state issued class A water and class A wastewater licenses
Permit levels are issued by the state
It depends on what chemical treatment is required and disinfection method

whoover

Since our cars have "lifetime" (10-year) coolant, OP was being reasonably skeptical and had his coolant tested.

The 10-year coolant requires three things to work, according to the factory. 1) you have to use special coolant, like Zerex G-05.
2) you have to mix it with water to 50-55% coolant/50-45% water.
3) you have to use distilled water.

You can get away with tap water only if your water is very, very soft, but the factory doesn't recommend it.

OP found that someone used hard tap water, and only he and MB messed with his coolant. The lab says to replace it

Pretty scary.

whoover

I'm not sure what "it" is, but there are no federal or state requirements for pH. States act on behalf of the federal government in implementing the requirements of the Safe Water Drinking Act. There is no primary standard in the Act for pH. There is a secondary (recommended) stardard, which is 6.5-8.5:
http://water.epa.gov/drink/contamina...ystandards.cfm

I don't think any state has set a primary standard. I know California hasn't because I know those regs very well. If California hasn't it's pretty unlikely that any state has.

Ingenieur

It is pH, the parameter under discussion
It is a required reportable on every permit issued in PA
The PA DEP issues the permits not the EPA
EPA standards are used as guidelines only as far as they are adopted
The limits and methods are in the PA Code
Allowable is typically 6 to 9 std units

Ingenieur

Scary??? Lol
You must have never been in a situation that induces fear
Much ado about nothing
We are reaching for minutia to worry about
Breath deep, it will be OK

pH is ok
Ratio is close
Boiling point is spec
I'd like see the actual report before drawing onerous conclusions

Ingenieur

http://www.mbca.org/sites/default/files/antifreedec04_0.pdf

Pretty good info
A primer

Ingenieur

You do the reporting for the system?
You do the lab work ?
Do you make process adjustments/decisions?
Are you licensed or certified?
Isn't that required in CA?

-Marlin-

Now it's coming in clear. Yeah, tap water would be a big no no in my book. Common sense tells me the minerals would wreak havoc on the system over a short period of time. Never knew that the ph of the water was an indicator, but now I see the correlation. Had a duh moment....

That headbolt issue is really concerning though. All those people out there that have a great car prior to the changeover........must have some level of anxiety in "when is it my turn" thinking.

Ingenieur

Scan the link I posted, it's not a real big deal
They formulate the coolant to inhibit scaling even in hard water
Yes distilled or deionized is preferred but mb sells vehicles all over the world and water quality is highly variable

I had a coolant issue yesterday
During my A5 service they topped it off, in fact overfilled it...a lot
Had to siphon a good bit out
I keep it spot on and it didn't need touched
White/black tab, I keep it right on the line when cold
I want to be able to detect any coolant loss

whoover

I answer to the California Department of Public Health. Monthly. Not you, but thanks for your interest.

roadtalontsi

MB service interval for coolant flush is 10yr/150k miles. So by saying NO SERVICE INTERVAL is wrong, just look at the service sheet.

Ingenieur

I'll take that as a no
In PA operating a system without a license is a criminal offense
So you have no license or formal training?

Ingenieur

People want drama it's 'scary'
I bet the 10 year/150k mile is conservative
Modern chemistry and materials negate a lot of old school habits

whoover

Assume much? It's not a great way to learn. One could assume you live in your mother's basement, but I would never do that.

Ingenieur

you still have not answered, just tossed out an insult
do you have a water system operator license?
again because of your redirection and obscuration I'll deduce, no
btw: an assumption is a first step in learning many times: I'll assume (some call it hypothesize) a force (vs. magic) is what causes an apple to fall, now I'll define that force, I'll prove my assumption

as previously stated my mother is dead: she no longer has need for possessions, as in 'her' basement....my mother actually lived with us before she passed...we don't have a basement, slab on grade


I'd still like to see the actual report to see how their conclusions were reached: ie, emergency level replacement, etc.
what is the concentration of calcium
dissolved solids
conductivity
etc.
but I'll 'assume' the result is the same, no big deal

motoman

The 325.1 spec callout is taken off the white plastic antifreeze bottle sold to me by my local MB dealer. So a typo on plastic. However, I do not see that number referenced in forum discussion.

Present facts or theories and curb the battle of egos that seems to accompany every discussion. For forum members who feel snowed by the "watered down" tech talk. Yes, do some basic reading on the subject and understand why they don't freely hand out degrees in chemistry . You got to put in some effort.