Coolant pH question

[Chuck1986]

I was just wondering if pH paper can be used as a way to determine if there are still sufficient corrosion inhibitor chemicals remaining in the mixture. For example, a 50/50 mixture of Peak Long Life and water has a pH of 8.0, if I monitor that pH and make sure it stays the same, does that mean the coolant still has enough inhibitors left?

 

[mazduh30]

That is exactly what Ph paper is design for. The rate of corrosion within a cooling system (acidity/alkalinity) is measured on a pH scale. If coolant remains alkaline, corrosion is inhibited. A reading 7 and below (pH) corrosion will start, go to high, you can strip the aluminum hydroxide layer off the aluminum surface. As a normal or average most state a pH between 9-11 is the best. I test every 3-4 months..overkill?, Not to me.

 

[Vilan]

pH paper will tell you how basic/acidic your coolant is, but there's more to it than that. There are protective chemicals in there that have nothing to do with pH. I've used special coolant testing strips that have several little indicator squares on them, one for pH, one for % glycol, and one for something else, I think it was to test the remaining OAT protection. A radiator repair shop should be able to hook you up with some.

 

[Big Jim]

I don't know the chemistry involved in the strips, but there are or were test strips availble commercially to test coolant. BG Products as well as MOC sold them to shops to push coolant flushes. The old style coolant uses a different strip than Dexcool. I suspect that it is it is a PH type of strip, but no real explanation was given.