STARTING
SYSTEM
These models use a separate
12
volt starting motor
mounted on the right hand side of the engine to drive
the flywheel.
It
is a standard automotive starting
motor with a solenoid for engaging the pinion and an
over-running clutch. When the solenoid is energized,
its core pulls in, shifting the pinion into engagement
with the flywheel
ring gear. At
the
same time,
contacts in the solenoid close to provide a circuit for
the starter motor. The starting motor remains engaged
until the starting switch is released.
If
engine
is
equipped with a start-disconnect switch, the starter
motor will automatically disengage flywheel gear when engine
speed reaches about
900
rpm.
The starter is protected from over-speed
by
an over-
running clutch which permits the engine to run faster
then the starter before the pinion is disengaged.
Figure
45
shows the starting circuit.
MAINTENANCE
Periodically check the starting circuit wiring for loose
or dirty connections. Inspect the starter commutator
and if
it
is dirty, clean with number
00
sandpaper (do
not use emery cloth or emery paper). Check the
brushes for poor seating on the commutator and for
excessive wear.
TESTING
Poor cranking performance can be caused bya faulty
starting motor, defective battery, or high resistance in
the starting circuit.
Check the charge condition of the battery with a
hydrometer.
Specific gravity should be between 1.290 and 1.225
when
75
percent charged. If not, recharge the battery.
Check electrolyte level.
If
battery will not recharge,
replace it. Keep battery connections tight and clean.
With
the starting motor operating, check the voltage
drops
(1)
from the battery ground terminal post (not
the cable clamp) to the cylinder block, (2) from the
cylinder block to the starting motor frame and
(3)
from the battery positive post to the battery terminal
stud on the solenoid. Normally, each of these should
be less than two volts.
If
extra long battery cables are
used, slightly higher voltage drops may result.
Thoroughly clean all connections in any part of the
circuit showing excessively high voltage drops.
If
starting motor tests are required, remove the motor
from the engine and test it on a bench. Test the free-
running voltage and current.
TO
START SOLENOID
GROUND CONNECTION
TO
ENGINE
nnnnn
FIGURE
45.
STARTING SYSTEM
Using a spring scale and torque arm, test the stall
torque, Figure
46.
Multiply the spring scale reading by
the arm length for the torque value.
If
free running speed is low, and starter has a high
current draw with low stall torque, check for tight,
dirty or worn bushings, bent armature shaft, or loose
field pole screws, allowing armature
to
drag. Check
also for shorted or grounded armature and field.
A
lowfreespeed with lowtorqueand low currentdraw
indicates an open field winding, high internal
resistance due to poor connections, defective leads,
broken or worn brushes, or scored, worn, or dirty
commutator.
35
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