Testing for electrolysis in cooling
voltmeter capable of reading both AC and DC currents is
required to test cooling systems. The meter needs to read
zero to the maximum voltage of the system being tested in
tenths of a volt. The meter leads must be long enough to
reach between the coolant and the groundside of the battery.
An ohm function of a voltmeter is very helpful to pinpoint
areas of resistance in as electrical system that will cause
an electrical current to ground through the coolant rather
than the engineered electrical circuit.
Attach the proper meter lead to the groundside of the
battery, negative-to-negative or positive-to-positive.
Install the second lead in the coolant touching the
Read the DC and AC voltage with all systems off. If a
block heater is present, also take a reading with the
heater turned on. If an automatic battery charger is
present, as a standby system, also take a reading with
this system running.
Read the DC and AC voltage with the electrical starter
Read the DC and the AC voltage with the engine running
and all systems turned on: lights, coolers, fans,
heaters, air conditioning, cell phone, two-way radio,
including the phone and radio on both standby and
The above procedure will test a complete system except
for an electrical current, which can be generated by the
rear end transmission. This is particularly true with
air bag suspensions, rubber pad suspensions and
rubber-mounted transmissions. Any current generated will
travel up to the drive shaft to ground through the
engine coolant. Grounding rear ends and transmissions is
Voltage of zero to .3 is normal in a coolant of cast
iron engine. Such an engine will be destroyed with time
by .5 volts, and engine manufactures are reporting .15
volts will destroy an aluminum engine.
The current will be AC if the problem is due to static
If the coolant shows an electrical problem with all the
equipment turned on; turn off one system at a time until
you finally turn off the system that stops the
electrical current. When the current stops, this will
indicate the electrical system causing the problem.
Be partially careful of starters. They can cause as much
damage to a cooling system as a direct connection to an
arc welder. This is due to the amperage present.
Always change the coolant if a current is detected. The
electrical current will destroy the protecting chemicals
in a properly inhibited coolant.
following are failures that are not manufacturer defects and
therefore not covered under warranty.
- Cooling systems require a through flush of the
radiator, engine, overflow tank, hoses and heater core,
failure to do so will lead to mixing coolants and
contaminates and creating a deadly cocktail for the
The correct coolant and distilled water mixture
prescribed by the coolant manufacture of choice must be
maintained. Water with high trace elements of minerals
will create problems for aluminum radiators not normally
seen in copper radiators.
– Electrolysis is the systematic removal of the
protective layer on the inside of the radiator tubes due
to improper grounding. Electrical grounding problems can
stem from poor installation of aftermarket accessories
or incorrect vehicle collision damages.