Chevrolet 70 1969 Series, Shop Manual

Page: 719 / 913

ENGINE ELECTRICAL 6Y-4
HEAVY-DUTY TYPE (Fig. 4)
1. Scribe a mark on the lever housing and nose housing
so parts can be assembled in same relative position.
2. D i s c o n n e c t f i e l d coil c o n n e c t o r f ro m s olen o id
“ m o to r” terminal and lead from solenoid ground ter­
minal.
3.
Remove inspection plates and disconnect field leads
from brush holders. Be sure to identify these leads for
proper installation.
4. Remove cap screws and lock washers which attach
co m m utator end frame to field frame. Remove co m ­
m utator end frame.
5.
Remove nose housing-to-lever housing attaching bolts
and remove nose housing from lever housing.
6. Remove lever housing-to-field frame attaching bolts,
then separate the field frame from the lever housing.
7. Remove arm ature and clutch assembly from lever
housing.
8. Separate the solenoid from the lever housing by pull­
ing apart.
INSPECTIO N, TESTS, A N D REPAIR
CLEANING AND INSPECTION
With starting m otor disassembled, except for removal
of field coils, component parts should be cleaned and in­
spected as described following:
1. Clean starting motor components; however, do not
use grease dissolving solvent for cleaning the overrun­
ning clutch, armature, brushes, and field coils.
2. Inspect overrunning clutch action. The pinion should
turn freely in the overrunning direction and must not
slip in the cranking direction. Inspect pinion teeth to
see that they have not been chipped, cracked, or ex­
cessively worn. Check the spring for normal tension
and the drive collar for wear.
3.
Inspect brush holders and brushes for wear or d a m ­
age.
4. Check fit of armature shaft in bushing in drive hous­
ing. If bushing is worn, replace. Apply silicone type
lubricant to the bushing before assembling.
5.
Inspect fit of bushing in co m m utator end frame. On
starting m otors shown in figure 1, the com m utator
end frame must be replaced if the bushing is damaged
or worn excessively. On all other models, the bushing
may be replaced.
6. Inspect co m m utato r for rough or out-of-round condi­
tion.
ARMATURE
Check armature to co m m utator leads to make sure
they are securely connected; then check the arm ature for
shorts, opens, and grounds.
Shorts - Place arm ature on growler. Hold a hacksaw
blade over the arm ature and slowly rotate arm ature (fig.
Figure 5 — D riv in g Re taine r O f f S n a p R in g
6). The saw blade will vibrate on area of short circuit. In­
spect co m m utator slots for brush dust or copper deposits.
Undercut mica to clean thoroughly retest.
Opens — Inspect points where co m m u ta to r riser bars
are joined to the com m utator for loose connections which
can cause arcing and burning. If bars are not too badly
burned, resolder riser bar leads using rosin flux solder.
After soldering, turn down co m m u ta to r and undercut
mica.
Grounds — Place one prod of a test lamp on c o m m u ta ­
tor and the other prod on arm ature core or shaft (fig. 7).
If test lamp lights, arm ature is grounded and should be
replaced.
At each end of arm ature shaft, examine bearing surfa­
ces for evidence of wear and spiral splines for damage.
Replace the arm ature assembly if shaft is worn or d a m ­
aged.
FIELD COILS
NOTE: Before checking field coils, disconnect
shunt field coil lead from brush holder bracket.
1. Place one test prod on field coil connector and the
other on each field coil lead. If lamp does not light,
coils are open circuited.
2. Place one test prod on field frame and the other on
each field coil lead. If lam p lights, coils are grounded.
3. If grounded or open circuit is indicated in series con­
nected coils, break the connection between coils and
test each coil separately to determine which one is de­
fective and must be replaced. If any coil is replaced,
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L