TM 5-3810-289-12
(3) Annually remove cranking motor from
and hold a thin strip of steel such as a hacksaw blade
engine and lubricate bushing of the drive and drive
about 1/32 to 1/16 inch away from the armature core.
spline. This bushing is in the nose housing and cannot
While holding the steel strip in position, rotate the
be reached without removing the cranking motor. Clean
armature slowly in the growler. A short circuit will pull
the splines of the drive with gasoline or kerosene to
the steel strip tightly against the armature core, and
remove any gummy deposit; then, apply a thin film of
cause the strip to vibrate. If a short circuit is found, the
light graph grease so the pinion will move freely.
armature must be replaced.
(3) Load test.
Note.
Do not use excessive oil or heavy oil
(a) Connect the starting motor in
series with a 12-volt, fully charged battery (a minimum
grease.
c.
Test.
specific gravity of 1.250) and an ammeter.
(b) The starting motor, turning
(1) Field coil. Make test only after coils
clockwise from the drive end, should draw between 85-
have been dried if they have been cleaned. With test
90 amps at 3800 rpm.
lamp prods, one held on the field ring and the other on
the field terminal, determine that the windings are not
grounded to field ring or pole pieces. If coils are shorted
4-38.
Solenoid Test and Replacement
or grounded, remove and inspect if they can be
a. Removal and Installation. Refer to figure
reinsulated to eliminate the trouble. Replace coils if
429 to remove or install the solenoid.
short or ground cannot be eliminated. Refer to internal
b. Test.
wiring diagram (fig. 4-26).
(1) After reassembly of the motor, the
(2) Armature.
switch solenoid is installed on the field ring and the
(a) Check the armature for grounds
timing checked for proper travel of the drive pinion on the
with a 110-volt test light by touching one probe to a
armature shaft.
commutator bar riser and the other to the armature core.
(2) The shaft lever is inserted through the
Test all commutator bars in this manner. If test light
switch cover seal. Make certain the nylock insert is in
glows, the armature is ground and must be replaced.
position in the threaded shaft, and that the shaft is
(b) Check armature for short circuit
aligned with the threaded hole in the plunger.
with a growler. Place the armature in the growler,
Figure 4-27. Starting motor, removal and installation.
4-37
