View Full Version : Voltage readings in Radiator

10-24-2001, 02:33 PM
Greetings, I am posting this info from another car list just to share with my friends found here. With dissimilar metals in the engine / cooling system, here is a method to gague when to change the antifreeze. Hope it has good information for you.
The problem of corrosion of various
parts of our engines is a major concern. It usually occurs at the
mating surfaces of two parts in contact with the coolant. It is
especially prevalent at the cylinder head, intake manifolds and water
pumps. One reason is the turbulence that occurs where this coolant
passages are of different sizes or shapes at the mating surfaces.
Correcting this is a little difficult at best.

The second source of erosion is the pH (acidity) of the coolant. When
the coolant becomes acidic or alkaline it is more corrosive to the
aluminum parts. The easiest way to determine weather or not the coolant
is corrosive is to check the voltage produced in the coolant.

Attach the ground probe of a digital volt ohm meter (DVOM) to the
negative (-) battery terminal.

Insert the positive (+) probe into the coolant and read the Voltage.

0.05 volts acceptable
0.10 volts borderline coolant
0.20 volts unacceptable

If the reading is 0.20 volts or greater the system should be drained and
FLUSHED. It may have to be flushed more than once to lower the voltage

Coolant with an unacceptable voltage reading that has not been in the
engine very long may indicate combustion gases in the coolant. The old
blown head gasket story.

01-11-2002, 08:01 PM
Ok, so this idea was posted back in October...has anyone actually tried this yet?