Evening star., 1918-06-23
AMMETER IS KEY
TO AUTO TROUBLE
knowledge of Its Language Is
Way to Locate All Motor
Ailments.

Watch your ammeter as a cat does a
mouse. 1t not only tells you when
matters are going properly. but fire.
quently warns you of impending trouble.
Learn to understand its indications and
you have gone long way toward mas
tering tho difficult subject Of trouble
finding.
First learn what the ammeter should
do under proper conditions. Turn on
each group Of lights and make note
of the amperage required by each. Put
out the lights and close ignition switch
Note that. Start engine and note at
current passing. Speed up the engine
and see that the ammeter needle does
not pass a certain point on the scale,
say about eight or ten ampere charging
rate. Turn on all lights and run en-
gine at the same speed as If you were
The ammeter should show charging
rate Of at least two amperes. Now
that you are familiar with its normal
behavior. you will be able to detect any
thing abnormal.
How to Tell.
For instance. when the engine is
the point of eight or ten amperes, or 1t
may move well above that point. This
shows trouble with the voltage regu-
later. whose function Is to prevent the
battery from overcharging. If 1t cuts
it down to too low charging rate the
of ignition, lamps and starter is not re-
placed as fast as used.
On the other hand. you may he charg
ing the battery at too high rate. This
will concentrate the acid by evaporating
to heat. II the battery terminals feel
hot the lamps should be turned on SO
as not to damage the battery. A tenn
perature of f20 degrees is ruinous. Con-
suit a battery man at the first oppor-
tunity or have the voltage regulator at
tended to by an expert. The leading
battery manufacturers maintain an ex-
tensive chain of service stations where
distilled water and inspection may be
obtained free Of charge. This service
they gladly give for the benefit of the
public.
when it should the fault may be in
the instrument itself. But look for
other indications before condemntng
the ammeter. If you turn on the
lighting switch and the lamps light,
but the needle does not move, the
fault is in the ammeter, but II the
lights do not come on the fault may
be in the fuse, the switch, a burned
out lamp or a defective wire or con-
nection either at battery or else
where.
The Compass Test.
If the ammeter does not show
charge" when the engine is running
at normal rate the generator may not
be producing current, due to some
internal defect, a carbon brush may
be sticking in it's holder. there may be
loose or defective wire, the am
meter may be at fault or the auto
matte cut-out may not operate. Give
the ammeter a slight jar to see IL
needle is stuck. Then use the compass
test. Lay small pocket compass on
the wire running from the generator
to the ammeter. This wire should
run north and south and the car
may have to be moved to bring 1T
compass needle will swing at right
angles to the wire as long as cur
rent Is flowing. If there is no cur
rent the needle Will not be affected.
II the lights are out and the engine
Is at rest and the ammeter indicates
discharge. the needle may be bent.
dfscharging the battery through the
generator. As this will ruin the wind
tngs OF the generator, 1t must be stop
ped Immediately. Remove the cover
OF the cut-out and separate the points
by hand. 1t is advisable to make a
specia! study Of your starting sys-
tenn. then watch your ammeter and
you will be well repaid.