[Brian]

Words of wisdom from the late, great Rumbleseat:


CHECKING COOLANT FOR RUST INHIBITORS AND THEIR CONDITION: As we all know,
anti-freeze never loses its anti-freezing ability. It may get dirty, but it
still has the same anti-freeze characteristics as when it was new. HOWEVER, the
inhibitors last only a fairly short time. The most common solution to this
problem, and I think what the manufacturers want us to do, is to replace the
anti-freeze. But why not just replenish the wore out rust inhibitors? Problem
is how to determine the inhibitors are no longer active.
Remembering our old high school physics..... Whenever dissimilar metals are
immersed in a liquid in motion, D-C voltage will result.... or something along
these lines. This will cause softer metals (like aluminum, zinc, brass, and
copper) to transfer to harder metals by electrolysis. Inhibitors prevent this by
reducing or eliminating electrolysis. Determining the condition of inhibitors
can easily be checked using a Volt-Ohm-Meter (VOM). A digital VOM is easier to
use than an analog (analog have scales and a needle) for this test. Turn the
function selector to D-C volts. You’ll be measuring voltages of less than 2
Volts so select a voltage of 5V or less. Hold one of the probes (either one)
suspended in the coolant in the top radiator tank. Don’t let it contact any
metal. Ground the other probe to the metal of the radiator filler or tank. Read
the voltage on the VOM. When the voltage exceeds 0.5 Volts D-C, the inhibitors
are worn out and are no longer doing anything. Adding a can of rust inhibitor is
all that’s required. A voltage reading of 0.5 Volts DC or less show the
inhibitors are still active and there is no need to replenish them. Remember,
anti-freeze never loses its anti-freeze capabilities...... it only looses its