GMC T Series 1994 Repair Manual page 596

CLEANING, INSPECTION, AND REPAIR
CLEANING
N O T IC E : D o n o t c le a n o r im m e r s e th e s t a r t e r
m o t o r p a r t s in g r e a s e - d i s s o l v in g
S o lv e n t s w ill d is s o lv e th e g r e a s e p a c k e d in
t h e d r i v e a s s e m b l y a n d m a y d a m a g e
a r m a t u r e o r f ie ld c o il in s u la t io n .
P iy i Clean
• All starter motor parts with a clean soft cloth prior
to testing.
INSPECTIO N
Inspection in the following steps refers to visual
inspection of the starter motor parts and assemblies to
determine their serviceability. Electrical tests for certain
assemblies are described in " Component Electrical
Testing."
Inspect (Figure 3)
I9
1. All parts for cracks, distortion, or other structural
damage. Replace parts or assemblies that are
cracked, bent, or otherwise damaged.
2. Threaded parts for stripped, crossed, or otherwise
damaged threads. Replace the parts with thread
damage that cannot be cleaned up using a suitable
tap or die. Replace any hardware items that have
damaged threads.
3. Solenoid assembly (19) for cut or torn boot. If the
boot is damaged, replace the solenoid assembly.
4. Clutch drive assem bly (34) for the following.
Replace the clutch drive assembly if damaged:
• Pinion gear turns roughly or turns in both direc­
tions.
• Pinion gear teeth are broken or show evidence
of step wear.
• The shift lever collar shows deep scoring or
other damage.
5. Brush holder assem bly (7) for the follow ing.
Replace if damaged:
• Loose riveted joints.
• Cracked or broken insulation.
6. Brushes (5 and 8) for excessive wear.
•M in im u m allowable brush length is 12 mm
(0.472 inch). Replace excessively worn brushes
in sets.
7. Drive end housing bushing (37) for scoring or other
damage. Replace the damaged bushing. Refer to
" Repair Procedures."
8. Ball bearings (12, 14, and 32) as follows:
A. Hold the armature (13) or drive shaft (31) and
slowly rotate the outer bearing race by hand.
B. Check that the bearing turns freely without bind­
ing or the feel of flat spots.
C. Replace damaged bearings. Refer to " Repair
Procedures."
9. Armature assembly (13) for the following:
• Gear teeth that are broken, or that show evi­
dence of step wear or root interference.
• Rough commutator surface. Polish with No. 400
s o lv e n ts .
grit polishing cloth if necessary. Thoroughly
clean metal dust from between the commutator
t h e
bars. If the com m utator surface cannot be
repaired in this manner, replace the armature
assembly. Do not turn the commutator in a
lathe.
•W o rn com m utato r. R eplace the a rm ature
assembly if the commutator outer diameter is
less than 36 mm (1.378 inch) or if the undercut
depth at any point is less than 0.2 mm (0.008
inch). Do not undercut the insulation.
10. Drive shaft (31) for the following. Replace the drive
shaft if damaged:
• Scored or damaged shaft where it turns in the
bushing (37).
• Internal gear with teeth broken or showing evi­
dence of step wear.
• Damaged spline. The clutch drive assembly
must slide smoothly and easily over the full
length of the spline.
COM PONENT ELECTRICAL
Perform the following electrical tests on the solenoid
(19), armature (13), and frame and field assemblies
(15) to determine their serviceability.
1. Using an ohmmeter, check the windings of the
solenoid assembly (19) for continuity as follows:
• Check the resistance of the solenoid pull-in and
hold-in windings in series by measuring the
resistance between the motor terminal (50) and
the solenoid case (figure 9). Resistance should
be about 1.95 ohms.
• An extremely high resistance reading indicates
a break or fault in the winding continuity. A very
low resistance reading indicates a short or
TESTING