View Full Version : Coolant pH values

05-14-2003, 02:31 AM
I got myself an electronic pH meter (about $50) to keep track of the effectiveness of my kidney stone medication. Don't ask!

Can any of you chemistry experts point me to refereneces on the idea pH values for various automotive liquids, especially coolant?


05-14-2003, 05:17 AM
The DIY channel had a show on car care and it went into the pH thing for coolant, you might give their website a paruse. (70% Snob I need to improve my vocabulary.)


05-15-2003, 02:34 AM
MATTP, Thanks for the suggestion. I haven't found the specific answer to coolant pH yet, but I did find lots of other interesting things. I'll keep looking.

05-15-2003, 03:01 AM
Hello Mattp,

a little tip from the land that invented snobbery, peruse doesn't have an 'A' in it.

Alec graemlins/cheers.gif graemlins/england.gif

05-15-2003, 05:56 AM
See, I said I needed to work on it. graemlins/lol.gif


05-16-2003, 01:15 AM
While you guys have been phydiling with spheling, I actually found a site with an answer to my own question.

Check the IQ Scientific Instruments site at
www.phmeters.com/pH_Application_Notes.htm (https://www.phmeters.com/pH_Application_Notes.htm)
for some interesting applications of ph meters, including the proper values for effective antifreeze. The pH should be between about 8 and 10 if the anticorrosion components are still effective.

Also included are notes on testing soil, wine, and yogurt. What more could you ask for!


Ken G
05-19-2003, 01:54 PM
This leads straight to a question I have been meaning to ask for a while. I live in San Francisco; freezing is not an issue, and in any case, my house heating system is in the garage and is not well lagged, so I claim to have the best heated garage in San Francisco. I am advised that it is probably better not to put ethylene glycol in my engine, but just plain water plus something to make the coolant a little alkaline. What should that something be? Bear in mind that the capacity is many gallons (three large watering cans!), so I am not going to use de-ionized water. Fortunately San Francisco water is good (very little scale in house piping).

Ken G, 1925 Rover 16/50 (San Francisco)

Dave Russell
05-19-2003, 10:11 PM

Unless your cooling system has marginal capacity I don't see any reason not to use about 40% ethylene glycol. If it is an environmental issue, use propylene glycol. They provide the necessary corrosion protection & water pump lube. Also an increase in boiling point temperature.

Not sure, but I would think that slightly acidic is better than alkaline.

If you don't want to use these, use plain tap water, not softened water, with some corrosion inhibitor/ water pump lube additive. There many of these available from your local auto stores. Penrite & Red Line are favored by many, but all are good.

05-20-2003, 03:09 AM
My suggestion would be to use the coolant recommended by the manufacturer. Modern coolants do much more than provide freeze protection. The increase in boiling point is equally valuable, especially if you have a car with marginal cooling capacity to begin with....not to mention any specific examples we all have.

Modern cars are designed to run at temperatures closer to the boiling point of water and the extra margin above 212F in the antifreeze solution is important. The pressurized coolant system also increases the boiling temperature along with the antifreeze solution's inherent higher boiling point.

My guess is that acidic coolant would readily attack the multiple metal components in the cooling system.


Ken G
05-20-2003, 12:50 PM
Thanks, Dave and Billca.

The service manual/driver's instruction book says "fill the radiator with soft water (e.g. rain water)"! The model was renowned for its not being possible to boil it, so any improvement or degradation in cooling from using something in addition to water is not an issue. I'll check into what Kragen stocks, but the usual problem with additives is that they don't tell you what they are; they merely make probably spurious snake-oil claims.

Yes, someone somewhere suggested that the various metal components would be protected by very slight alkalinity. Someone else indicated that it was unwise to put glycol into engines that predated its use, but I am not sure what damage if any it might cause. (When I took over the car a year ago it contained antifreeze because that was necessary in England).

At present I am likely to be draining and refilling several times, as I chase minor leaks, so I am not prepared to put in expensive chemicals.

Ken G, 1925 Rover 16/50 (San Francisco)

06-25-2003, 11:06 PM
Interestingly, raising the boiling point by using antifreeze may NOT help cool your car better. Antifreeze inhibits the ability of the cooling system to remove heat. Plain ol' H2O removes the heat better than glycol. Here is a link to the Water Wetter page that explains the advantage of not using antifreeze. <https://www.racerpartswholesale.com/redtech3.htm>. It's a "Red Line" product plug, but it makes sense.