Can hydrometer check pH balance of coolant?

Rudy Technician Utah Posted   Latest   Edited  

We have a service writer who insists a coolant hydrometer can be used to check the pH balance of coolant. His complaint is that the coolant test strips are expensive and unnecessary, if all of the techs have a hydrometer. 

As far as I know, a hydrometer cant be used to determine coolant acidity. 

I welcome corrections to either line of thinking.

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Dick Diagnostician
New Hampshire
Dick
 

A hydrometer checks specific gravity to determine freeze protection only .

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David Owner/Technician
Australia
David
 

It sounds like he’s trying to re-invent the wheel. As far as I know a hydrometer checks specific gravity which will give you a coolant/water concentration, although I believe a spectrometer will give a much more accurate level. The only easy way to check acidity or ph level is with the test strips. I will happily be corrected on this if wrong, as I am sure there are others in this group with…

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Paul Owner/Technician
California
Paul
 

Well, if changes in PH somehow changed specific gravity, then maybe, but I'm pretty sure it doesn't. And even if it did, the hydrometer would only show a combination of the effects of PH on the coolant's specific gravity combined along with the coolant/water ratio's changes to specific gravity, so there would be no way to tell which changed the reading. I'm sure you just posted this to show…

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Nate Owner
California
Nate
 

I think the hydrometer is measuring the specific gravity of the fluid, and that's how it calculates the concentration of coolant in the fluid. I don't see how it could possibly measure pH.

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Michael Technical Support Specialist
California
Michael
 

Your SA is incorrect, A hydrometer checks state of charge by measuring the specific gravity of the battery fluid. The battery state of charge changes the specific gravity of the battery “acid” The PH doesn't change, at least not enough to determine anything. I really doubt it would change more than a tenth of a point. Isn't it amazing how much techs have to deal with science and chemistry?…

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Jared Diagnostician
Maryland
Jared
 

Hydrometer measures gravity (a necessary tool when brewing beer as well!!). Litmus strips, dye drops (only works on clear liquids), and electronic pH meters/pens are the only ways I've ever obtained pH of liquids.

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Matthew Owner/Technician
Tennessee
Matthew
 

Ask him if it is possible to measure current flow with a pair of pliers. Current clamps are expensive if all of the techs have pliers. Also, regular pH strips work with any aqueous solution. They don't have to be made for coolant. I was in a lab a few times, back in the day.

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Lee Owner/Technician
Michigan
Lee
   

Your service writer is completely wrong. As others have mentioned, a coolant hydrometer measures specific gravity, not pH. And your techs are better off using a refractometer instead of a hydrometer to measure the coolant protection. Cost is about the same as a glass tube hydrometer, the refractometer is smaller and more accurate, and does not easily break unlike a glass tube hydrometer.

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Glenn Owner/Technician
Texas
Glenn
   

Hi Rudy, Can the same hydrometer be used, yes, but it is not that simple? The biggest thing to realize is Specific Gravity. Plain water has a Specific Gravity of 1.0. Any other liquid added to this water will alter that reading. A hydrometer measures this difference. Test strips are accurate, and they test PH (just don't expose them to the sun for long periods or get old), a cheaper…

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Mark Engineer
Colorado
Mark
 

Rudy You wrote: “service writer who insists a coolant hydrometer can be used to check the pH balance of coolant. ” It appears that somehow your service writer is aspiring to be in the government or a politician, and therefore, can violate the laws of physics just “because he says so”. He as spoken, therefore the laws of physics no longer apply. As others have written, a coolant hydrometer is…

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George Owner/Technician
California
George
 

Does the writer have numbers or a conversion table?

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Randall Technician
Pennsylvania
Randall
 

Rudy, It seems to me it that perhaps it is really more of a matter of return on investment. As opposed to a scientific question. If your techs are doing the tests, and someone is analyzing them and selling flush services successfully— based on the results. The test strips will cover their cost. However… Everywhere I have worked and they tried it, somehow it failed to be marketed…

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Michael Owner/Technician
Alaska
Michael
 

I have never seen a hydrometer or refractometer that will measure PH. I do have an electronic PH tester, but it cost more than a hydrometer, takes about 30 to 45 seconds to get a reading, and requires calibration fluid to zero it. Test strips are much faster and more cost effective.

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Donny Manager
Colorado
Donny
 

A hydrometer is fundamentally useless with modern coolants that have different specific gravities. It tells you nothing useful. It is a series of balls that float. They cannot determine pH and are not very good at determining freeze or boiling points for that matter. Doesn't matter though. By the time stock coolant is failing this test it has been doing damage for a long time. You need a…

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Martin Instructor
British Columbia
Martin
 

Rudy, just inform him that he is wrong and it is clear that he needs schooling in coolants and servicing techniques, so that he can better serve your customers by knowing what he's talking about. Next, he will arguing about the cost of using too many different expensive coolants, that are just marketing hype and different colours for no good reason! Send him to Kevin's classes on fluids, on…

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Glenn Owner/Technician
Texas
Glenn
 

Hi Martin, I have replaced to many heater cores and radiators in recent years due to so called “universal coolant antifreeze”. Often times that stuff has chemical conflicts and it will Gel up in radiators and heater cores. A pH test will not show the chemical makeup of coolants. Even test strips will not show this. I recommend for people to only use what the manufacturer recommends, and it…

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Martin Instructor
British Columbia
Martin
 

Agreed Glenn. Working at a GM dealership or any dealership or independent shop, the safest way to ensure that the correct fluids for any system on the vehicle are used, is to identify the correct specified fluid for the application. However, there are additional factors to consider, even when going the OEM specification route. Always reasearch Bulletins and/or Service Manual Updates that…

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Kevin Owner/Technician
Arizona
Kevin
 

Tell him the best way is to taste it.

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Glenn Owner/Technician
Texas
Glenn
 

Oh! that's mean… but funny huh?

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Glen Owner/Technician
Illinois
Glen
 

Taste strips :)

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Paul Mechanic
Alaska
Paul
 

No

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Rudy Technician
Utah
Rudy Resolution
 

Appreciate the input gents. I was certain he was incorrect, however sometimes you don't know what you don't know, so I thought Id double check with my peers.

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Rudy Technician
Utah
Rudy Update
 

Id just like to add to this. We are a 5 store company and the cost of the strips is $7000 a year After I insisted the strips were the only way to test for PH balance and referenced this thread as further evidence, the powers that be decide to look deeper into the ROI. Turns out were doing over $140k a year on the coolant and brake flushes based off of strip recommendations(the strips in…

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Glenn Owner/Technician
Texas
Glenn
 

Hi Rudy, Once they took the blinders off, they could see more clearly. Maybe they need to look elsewhere for saving money and keep costs under control, like having the techs exchange an empty spray can each time they need a new one or turn in empty tubes or cans of RTV gasket maker. One shop I worked at years ago did that and it stopped a lot of shop materials loss. I've seen more than one tech…

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Mark Engineer
Colorado
Mark
 

Glenn Although monitoring shop supplies would help (and Fastenal has a great vending machine for that task) I suspect we might find some layers of management that could be culled. All too often I see too many bosses and not enough workers and when it’s time to tighten the belt and trim costs management gets rid of a worker bee. I also most often see management stepping over a hundred dollar…

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Martin Instructor
British Columbia
Martin
 

Absolutely correct Mark. Inept management with a focus on maximising their own bonus/commission related annual incomes by cost cutting, so frequently affects the quality of materials and components made available for service and repairs. Backed by the company “bean counter”, a “one man case of argument for a spec quality fluid or component can "fall on “deaf ears” as an uphill battle. I was…

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David Owner/Technician
Alberta
David
 

Martin, I wonder about a business model that does not charge for the pH strips used? Or how they have someone on the front line with not enough knowledge to perform the job properly? What other brilliant mistaken ideas might be in that persons' head? Wow! How did density become confused with hydrogen ion levels in this application? When someone suggests a phenomenon to me that make little or no…

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Martin Instructor
British Columbia
Martin
 

Agreed David. That really made no sense at all to me. Customers should be charged for all sundry items relaevant to their vehicle diagnosis, service and repairs. Just as we have technicians in the field exhibiting a widely varying range of skills, there are “intermediate” staff acting to convey customer concerns to technicians, also with a wide variance in abilities. While we don't want them…

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