Onan DJA Series User Manual

KNIFE SWITCH
SCALE
GROUND ON
fl MOTOR AT .
UW POINT FREE ^^^S^ \
OF GREASE ^ ^ ^ ^
AND PAINT
VARIABLE RESISTANCE
FIG. 9-2
age and current. Limits are given in the Table of Dimensions
and Clearances.
Using a spring scale and torque arm, test the stall torque
(Fig. 9-2). Multiply the spring scale reading by the. arm
length for the torque value.
If free running speed is low, and 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, shorted armature, or grounded armature or
field.
A low free speed with low torque and low current draw
indicates an open field winding, high intemal resistance
due to poor connections, defective leads, broken or worn
brushes, or scored, worn, or dirty commutator.
High free speed with low developed torque and high current
draw indicates shorted fields. Since there is no easy way
to detect shorted field coils, replace and check for improved
performance.
The voltage drop across the solenoid on the starting motor
should be less lhan 1.5-volts. If not, remove it for repair.
REMOVAL AND DISASSEMBLY, STARTING MOTOR
1. Remove connections to coiitrols and battery at the shift-
ing solenoid.
2. Remove nut holding rear mounting bracket to the engine.
3. Remove the blower housing.
4. Remove flywheel (early models).
5. Remove the three cap screws holding the starting
motor flange to the engine and pull out the motor.
6. Remove the Unk pin holding the shift lever to the
solenoid plunger and remove the shift lever center
pin.
7. Remove the thru bolts from the commutator end of the
motor. Pull off the end cover and lift the brushes off
their seats.
8. Pull the cast housing from the front end of the motor
and lift the armature and clutch out of the motor frame.
9. To remove the over-running clutch from the armature,
drive the retainer away from lock ring near the front
end of the shaft, remove the lock ring and pull the
assembly off. Do not attempt to disassemble the
clutch assembly.
10. If necessary to service the solenoid, remove the
four cap screws and electrical connection holding it to
the motor frame. Remove the two screws on the rear of
the solenoid to reach the switch contacts.
11. If it is necessary to remove the starting motor flange
(Fig. 9-4), watch for shims between the flange and
crankcase surface. Save any shims, they must be
reinstalled to position the starter correctly.
REPAIR, STARTING MOTOR
Armoture: Inspect the aimature for mechanical defects
before checking for grounds or shorted.coils.
To test for g-ounds, use a 12-volt test lamp and check
between each segment of the commutator and the shaft. Do
not touch probes to the commutator brush surfaces; this will
burn the smooth surfaces.
A growler is necessary to test for shorted coils. With the
armature in the growler, run a steel strip over the armature
surfaces. If a coil is shorted, the steel strip will become
magnetized and vibrate. Rotate the armature slightly and
repeat the test. Do this for one complete revolution of the
armature. Replace the armature if it has a short or ground.
If the commutator is only dirty or discolored, clean it with
#00 or 000 sandpaper. Blow the sand out of the motor after
cleaning. If however, it is scored, rough or worn, turn it
down in a lathe.
PUSH
PLUNGER
STARTING MOTOR NEED
NOT BE REMOVED FROM
ENGINE TO MAKE THIS
MEASUREMENT
' FEELER GAUGE
C.07"-.I2"CLEARANCE.
SEE TEXT)
FIG. 9-3
24

Onan DJA Series Specifications

General

Brand	Onan
Model	DJA Series
Category	Engine
Language	English