Coolant PH level questions.

[Grand cherokee hemi]

I recently completely flushed my cooling system and replaced the coolant. I did a very thorough flush using a radiator flush kit, distilled water and flushing several times. I removed my thermostat, put the heater on high and drained my reservoir tank. I had completely clear water draining out prior to re-adding coolant. I added 2 jugs of the new coolant which was prestone concentrate. The jugs were 3.78L each for a total of 7.5L of concentrate added. The capacity of my cooling system is 15.3L so I figured that using 7.5L of coolant would give me a 50/50 mix (or very close) which is what is recommended. After doing this I went to a local oil change shop and asked them to test the ratio using there ANTIFREEZE COOLANT TESTER. They sucked up a sample and said it was good for about -35 C. They explained that this was a little warmer than they usually go (they like to see -45 to -50) but because I live in a place which rarely goes below zero and never below -10 then it should be fine. I did not have them test the acid/ph level at this time. 2 weeks later (today) I went for an oil change and they tested my coolant with a little strip of paper. My PH level was 5.5 which is low (should be a min of 7 and ideally between 9-10). The test was conducted right in front of me so am not concerned about them misleading me.

My question is (which they weren't able to answer) if I drain out some of my coolant and add some more of the concentrate (making my ratio stronger) will that increase my PH level? I've tried to look on google but can't find anything specific. Is my PH level low because my ratio of water is on the high side, or does the ration of coolant to water have nothing to do with the PH level.... thanks

 

[ripcord]

Pure coolant is alkaline and a ph of 5.5 is definitely a problem, but the fact that you just flushed and added fresh coolant makes me think there was a measurement error of some sort. You can buy litmus test strips at Walmart - I would verify it myself before doing anything else.

Edit: to answer your question, the acidic ph is not from your coolant to water ratio. Pure water is 7 and coolants are higher (numerically) so if anything you should be higher than 7 as long as you had SOME fresh coolant in it.

 

[Chris142]

Leave it. -35f is 50/50. No reason to add more coolant. Something weird is up with their tester. Modified to lie maybe?

 

[Grand cherokee hemi]

Pure coolant is alkaline and a ph of 5.5 is definitely a problem, but the fact that you just flushed and added fresh coolant makes me think there was a measurement error of some sort. You can buy litmus test strips at Walmart - I would verify it myself before doing anything else.

Edit: to answer your question, the acidic ph is not from your coolant to water ratio. Pure water is 7 and coolants are higher (numerically) so if anything you should be higher than 7 as long as you had SOME fresh coolant in it.

so adding more coolant concentrate (increasing my ratio) won't increase my ph level (decrease my acid level) then

 

[ripcord]

Adding coolant will make it more alkaline, but I'm suspicious of that 5.5 value. I would get some test strips and check it first.

 

[Grand cherokee hemi]

so adding more coolant concentrate (increasing my ratio) won't increase my ph level (decrease my acid level) then

if what your saying is true then i don't understand how i could have low ph... if anything my ratio was a little light (more water than coolant) and the coolant is brand new. Does anything else cause low PH?

 

[Grand cherokee hemi]

Adding coolant will make it more alkaline, but I'm suspicious of that 5.5 value. I would get some test strips and check it first.

that's what they tested it with.... i guess ill go buy my own...walmart has them you say?

 

[Leo99]

so adding more coolant concentrate (increasing my ratio) won't increase my ph level (decrease my acid level) then

No. Water has no buffering capacity and since it has no ions, you can't really measure its pH. It's not a dilution situation that you're thinking it might be. You didn't dilute out the pH. What was in that flush kit? Any chance some of that got left in the system? If that was acidic and got left in it could buffer the coolant down to what you're seeing.

 

[ripcord]

You can order them there at least. Amazon, too.

 

[Snagglefoot]

No. Water has no buffering capacity and since it has no ions, you can't really measure its pH. It's not a dilution situation that you're thinking it might be. You didn't dilute out the pH. What was in that flush kit? Any chance some of that got left in the system? If that was acidic and got left in it could buffer the coolant down to what you're seeing.

Better get your chemistry book out. Yes, fresh water will dilute a high ph fluid resulting in a lower pH, and removing some of the mixed fluid and adding more pure coolant will increase it again. The pH number is the concentration of hydrogen ions expresses as 10 to the power of negative X. Add more fresh water and you will dilute the concentration of hydrogen ions. However, I agree that something is wrong with the resulting 5.5 observed.

 

[Grand cherokee hemi]

Better get your chemistry book out. Yes, fresh water will dilute a high ph fluid resulting in a lower pH. The pH number is the concentration of hydrogen ions expresses as 10 to the power of negative X. Add more fresh water and you will dilute the concentration of hydrogen ions. However, I agree that something is wrong with the resulting 5.5 observed.

Thank you so much.... the good news is its only been a couple weeks so not long enough damage anything... tomorrow I will drain out 2 liters of the coolant and replace with fresh concentrate. Then I will repeat the strip test (somewhere other than where I got the first test) and see if it makes any difference.

 

[mfewtrail]

Test it again with a test strip yourself instead of wasting money and time replacing coolant that shouldn't have anything wrong with it. Plain pH strips are cheap.

$3 shipped if you have prime: https://www.amazon.com/Litmus-Strips-Universal-Application-Paper/dp/B085LK9PF6/ref=sr_1_1?dchild=1&keywords=ph+test+strips&qid=1609673437&refinements=p_76:1249158011&rnid=1249156011&rps=1&s=industrial&sr=1-1

Those will work exactly like the pH portion of the expensive coolant specific test strips. Get yourself a cheap(sub-$20) refractometer to test coolant ratios and save yourself future trips to the shop just for this simple testing...


My latest fill(50-50 dexclone and distilled water) has a pH of 9 for what it's worth.

 

[kschachn]

If you didn’t use an acidic flushing agent that was partially left behind then there’s something wrong with the test strips they used.

 

[Ed_Flecko]

I think this is why it's just plain easier to use pre-mixed coolant and avoid "flushing" of any kind, if at all possible. Why introduce plain water or a foreign chemical of any type, again..."if" at all possible.

Ed

 

[Leo99]

Better get your chemistry book out. Yes, fresh water will dilute a high ph fluid resulting in a lower pH, and removing some of the mixed fluid and adding more pure coolant will increase it again. The pH number is the concentration of hydrogen ions expresses as 10 to the power of negative X. Add more fresh water and you will dilute the concentration of hydrogen ions. However, I agree that something is wrong with the resulting 5.5 observed.

You're correct in an unbuffered solution. Coolants are buffered solutions. If the pH of coolant is basic and the 50/50 mixture is acidic then something must be bringing the pH down. Adding DI water won't change the pH in a buffered solution until you dilute out one of the buffering agents.

After more thought, it's likely there is a little acidic flush left in the system that is overcoming the buffering capacity of the coolant and lowering the whole system down to 5.5 and if you could dilute that acid out enough, the coolant buffering will win and raise the pH to acceptable levels. I don't think it will happen as there already is a high amount of coolant in the system and the dilution of the acidic portion will be minimal.

Or the pH reading was erroneous.

 

[Snagglefoot]

I checked the web and there is a serious amount of feedback on the paper pH products being totally inaccurate. I’m going to bet this is case here.

 

[kschachn]

I checked the web and there is a serious amount of feedback on the paper pH products being totally inaccurate. I’m going to bet this is case here.

They're not totally inaccurate. If there is enough water in the system then it should clearly indicate if the solution is acidic or basic.

 

[kschachn]

You're correct in an unbuffered solution. Coolants are buffered solutions. If the pH of coolant is basic and the 50/50 mixture is acidic then something must be bringing the pH down. Adding DI water won't change the pH in a buffered solution until you dilute out one of the buffering agents.

After more thought, it's likely there is a little acidic flush left in the system that is overcoming the buffering capacity of the coolant and lowering the whole system down to 5.5 and if you could dilute that acid out enough, the coolant buffering will win and raise the pH to acceptable levels. I don't think it will happen as there already is a high amount of coolant in the system and the dilution of the acidic portion will be minimal.

Or the pH reading was erroneous.

If it's only water you're adding then you'll never cross the neutral point. Even if he's adding coolant then you've already used up some of the buffering capability of the new coolant, I think if the pH reading is correct then it should be flushed again with clean water and filled with new coolant.

 

[Snagglefoot]

They're not totally inaccurate. If there is enough water in the system then it should clearly indicate if the solution is acidic or basic.

I’m thinking there are cheap inferior products out there. There are complaints of strips not even changing color when used with base and acidic solutions.

 

[Leo99]

If it's only water you're adding then you'll never cross the neutral point. Even if he's adding coolant then you've already used up some of the buffering capability of the new coolant, I think if the pH reading is correct then it should be flushed again with clean water and filled with new coolant.

I think you're correct. I was thinking it's possible there was something like 5 mL of really strong acid left in the system and it was bringing the whole system down. If you could remove 1 mL of this acid through draining and refilling with water or coolant it might be enough to overcome the acid's buffering capacity. It's unlikely.