Coolant pH

nah.....never heard of it........but why on earth would you need one?........hydrometers are cheap and reliable......

Because a hydrometers only tells you the concentration of antifreeze, while a pH meter will tell you how well the antifreeze is still working.

I may be ignorant, but I know some chemistry.

What does the pH have to do with the effectiveness of the coolant?

i think it was that the pH level shows how acidic or corrosive the coolant is.

Corrosion is usually less, at least on steel and some other metals, when the pH is elevated to between approximatey 8.5-9 . The coolant packages have buffer systems which attempt to keep the pH in the most effective range.

If the pH is too high, the compound will attack aluminum or even zinc ('pot metal'). If too low, steel will be attacked, brass can be dezincified, etc. Low pH also can desolubilize some of the components of the corrosion inhibitor package, such as the silicates (if they are used), the organic acids, etc.

I wouldn't pay a lot of money for one of these pocket pH devices. It is just one measurement.pH indicating paper tabs are available, as are swimming pool pH devices.

There are two things the coolant must do. Fundamentally it must of course cool. But it must also protect from corrosion. Antifreeze's first job is as a coolant. But a corrosive coolant is not a good idea. Antifreeze must be periodically replaced because the corrosion inhibitors go bad. The coolant then will still COOL, but the corrosion will prevent proper heat transfer, and there might even be damage to certain areas.

Hydrometers don't tell you dick about the health of the corrosion inhibitor package in the coolant, only that its still got enough specific gravity to provide freeze protection. You need to know pH to estimate how good the corrosion inhibitors are.

Of course with the new acid-based coolants, who knows what a "safe" pH is anymore either :-/

What's the opinion on coolant/antifreeze filtration?

I dont know of anyone who does it, nor is it generally necessary.

Fine for big diesels with huge cooling systems and active coolant additive control systems, but silly for automobiles. In fact, I've never heard of any automotive system.