martin:

definitely a tried and true method. essentially a measure of ph. over
about 0.5 V coolant is acidic (ph below 7), and much higher readings, say
5 V, suggest major electrolytic currents, which i understand have been
known to also damage automatic transmissions. distilled water has a ph of
7; fresh 100% eg antifreeze 12. emphasis on "high" in high impedence
meter, as voltage reading will decay rapidly for low impedence instruments.

dan

On Mon, 1 Oct 2007 00:33:05 -0400, Poppie Jagersand
<poppie.jagersand@YAHOO.CA> wrote:

>One of the house and woodworking magazines gave the following procedure
to check if the coolant is too old and needs to be changed:
>
>1. Open pressure reservoir cap.
>2. Warm engine until thermostat opens and coolant circulates.
>3. Use a high impedance digital multimeter to measure voltage
>between battery negative terminal and coolant. That is stick
>one lead into the coolant reservoir (that's why you opened the cap
>before warming the engine) and one on the battery negative
>terminal.
>
>4. If voltage <0.4V coolant is still good.
>
>That's the procedure. Now how accurate (or right) it is I don't
>know. I guess the idea is to find out if the additives in the
>coolant to prevent corrosion are still working. If they don't work
>anymore one could expect galvanic currents and a small voltage
>potential between ground and the coolant.
>
>Martin
>
>
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