STARTING
Most engine installations use a starting motor, as
shown in Figure 57.The starting motor mounts on the
right side of the engine and drives the flywheel for
starting. It is a standard automotive starting motor
with solenoid shift and over-running clutch, con-
trolled by a start solenoid
in
the control box. When the
control box solenoid energizes, the solenoid on the
motor operates, shifting the starter pinion to engage
the flywheel ring gear and closing the circuit to the
starting motor. The starting motor remains engaged
until after the engine starts when the control circuit
centrifugal switch closes, completing the starting
cycle. The over-running clutch protects the starter
armature from overspeeds.
ONAN does not stock all parts for the starting motor. See an
authorized dealer.
MAINTENANCE
Check the battery water level and charge condition
about every 100 hours. Every
500
hours inspect all
starting system wiring for loose or dirty connections,
especially connections to the battery terminals.
Separate Starting Motor:
Every
500
hours check for
loose or dirty connections. Check the battery water
level and charge condition every
100
hours. Inspect
the starter commutator and if it isdirty, clean with
#00
sandpaper.
Do
not use emery paper or cloth! Check
the brushes for excessive wear and poor seating on
the armature.
START
I
NG
MOTOR
TESTING
Poor cranking performance can be caused byafaurty
starting motor, defective battery or high resistance in
the starting circuit.
Battery:
Check battery condition with a hydrometer.
Specific gravity should be between 1.260 and 1.225. If
not, recharge the battery. If the battery won't
recharge, replace
it.
Wiring:
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. Each drop should be
less than
0.2
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.
Starting Motor:
If starting motor tests are required,
remove the motor from the engine. Complete starting
motor tests should include both tests of free-running
voltage, speed and current and tests of stall torque,
voltage and current.
To
test the free-running characteristics, connect the
starting motor
in
series with a battery and ammeter
and install a tachometer on the motor. Read the free-
running current and speed.
TO
START
SOLENOID
IN
CONTROL
BOX
t
,
FIGURE
57.
STARTING
SYSTEM
44
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