Chevrolet 1977 light duty truck, Service Manual

Page: 636 / 861

O N -V E H IC L E SERVICE
M A I N T E N A N C E A N D A D J U S T M E N T S
Lubrication
No periodic lubrication o f the starting m otor or solenoid
is required. Since the starting m otor and brushes cannot be
inspected w ithout disassembling the unit, no service is
required on these units between overhaul periods.
C O M P O N E N T P A R T R E P L A C E M E N T
S T A R T IN G M O T O R
R e p la c e m e n t
The following procedure is a general guide for all
vehicles and will vary slightly depending on series and model.
1. Disconnect battery ground cable at battery.
2. Raise vehicle to a good working height.
3. Disconnect all wires at solenoid terminals.
N O TE: Reinstall the nuts as each wire is disconnected
as thread size is different but may be mixed and stripped.
4. Loosen starter front bracket (nut on V-8 and bolt on
L-4) then remove two m ount bolts.
N O TE: On V-8 engines incorporating the solenoid heat
shield, remove the front bracket upper bolt and detach
bracket from starter motor.
5. Remove the front bracket bolt or nut and rotate
bracket clear of work area then lower starter from vehicle by
lowering front end first — (hold starter against bell housing
and sort of roll end-over-end).
6. Reverse the removal procedure to install. Tighten the
m ount bolts first, then tighten the brace bolt.
7. Check operation of starter on vehicle.
C H E C K IN G P IN IO N C L E A R A N C E
W henever the starter m otor is disassembled and
reassembled, the pinion clearance should be checked. This is
to make sure that proper clearance exists between the pinion
and pinion stop retainer when pinion is in cranking position.
Lack of clearance would prevent solenoid starter switch from
closing properly; too much clearance would cause improper
pinion engagement in ring gear.
1. Connect a source of approximately 6 volts (3 battery
cells or a 6 volt battery) between the solenoid "S" terminal
and ground.
C A U T IO N : D o n o t use m ore than 6 volts or the
m o to r will operate. A s a further precaution to
prevent motoring, connect a heavy ju m p e r wire
from the solenoid m o to r terminal to ground.
2. A fter energizing the solenoid, push the pinion away
from the stop retainer as far as possible and use feeler gauge
to check clearance between pinion and retainer (Fig. 6D-15s).
3. If clearance is not between .010'' and . 140" it indicates
excessive wear of solenoid linkage, shift lever mechanism, or
im proper assembly of these parts.
N O TE: Pinion clearance cannot be adjusted. If
clearance is not correct, m otor must be disassembled and
checked for the above mentioned defects. Any defective
parts m ust be replaced.
B E N C H T E S T OF S T A R T IN G M O T O R
To obtain full performance data on a cranking motor,
or to determ ine the cause of abnorm al operation, the m otor
should be removed from the engine and be submitted to a
no-load test with equipment designed for such tests. A high
current carrying variable resistance should be connected into
the circuit so that the specified voltage at the starter m otor
may be obtained, since a small variation in the voltage will
produce a marked difference in the current draw.
(a) No-Load Test. Connect the starter m otor in series
with a 12 volt-battery and an am m eter capable of indicating
several hundred amperes. If an RPM indicator is available,
set it up to read arm ature RPM . Check current draw and
arm ature RPM at the specified voltage.
1. Low no-load speed and high current draw may result
from:
(a) Tight, dirty, or worn bearings, bent arm ature shaft
or loose field pole screws which would allow the arm ature
to drag.
(b) Shorted arm ature. Check arm ature further on
growler.
(c) A grounded arm ature or field.
Check for grounds by raising the grounded brushes and
insulating them from the com m utator. If the starter m otor
has shunt field coils which are grounded to the field frame,
disconnect these fields from gound. Then check with a test
lamp between the insulated terminal and the frame. If lamp
lights, raise other brushes from com m utator and check fields
separately to determ ine w hether it is the fields or arm ature
that is grounded:
2. Failure to operate with high current draw may result
from:
(a) A direct ground in the term inal or fields.
(b) Frozen shaft bearings which prevent the arm ature
from turning.
3. Failure to operate with no current draw may result
from: