GMC 1976 ZEO 6083 Maintenance Manual page 408

6Y- 2 8 ENGINE ELECTRICAL
9. If output is within 10 amperes of rated output,
test regulator with an approved regulator tester, and
check field winding.
10 . If output is not within 10 amperes of rated
output, check the field winding, diode trio, rectifier
bridge, and stator as previously covered .
ASSEMBLY
Assembly is the reverse of disassembly.
Remember when assembling the pulley to secure
the rotor in a vise only tight enough to permit tight-
ening the shaft nut to 40-60 lb . ft . If excessive pres
sure is applied against the rotor, the assembly may
become distorted. To install the slip ring end frame
assembly to the rotor and drive end frame assembly,
remove the tape over the bearing and shaft, and
make sure the shaft is perfectly clean after removing
the tape . Insert a pin through the holes to hold up
the brushes. Carefully install the shaft into the slip
ring end frame assembly to avoid damage to the seal .
After tightening the thru-bolts remove the brush re-
taining pin to allow the brushes to fall down onto the
slip rings.
GENERATOR INSTALLATION
1 . Attach generator to mounting bracket and in-
stall adjusting arm. Tighten flange-type lock nuts
securely .
2. Place drive belt(s) over generator drive pulley
and adjust belt tension. Tighten mounting bolts and
adjusting arm bolt when belt tension adjustment has
been made . Refer to "Generator Drive Belt Tension
Adjustment" later in this section.
3. Push the wiring harness connector into the
socket making sure the lock on the connector en-
gages the end frame. Place harness clip on ground
terminal marked "GRD" and connect the ground
wire to terminal .
4. Attach red wire to "BAT" terminal on genera-
tor and fit boot on terminal .
5. Perform "Generator Output Test" described
earlier in this section to determine if generator is
operating properly .
GENERATOR DRIVE BELT
TENSION ADJUSTMENT
Because of the higher inertia and load capacity of
rotor used with A.C . generators, PROPER BELT
TENSION MUST BE MAINTAINED .
All generators are pivot-base mounted with the
belt tension adjustment arm at the top or bottom
using belt tension Tool BT-33-73F (Burroughs Tool)
or other suitable tool to check tension on each in-
dividual belt . If tension is not within 70-801bs . (used
belts) or 110-140 lbs. (new belts), loosen adjustment
arm clamp bolt and move generator to obtain recom-
mended tension .
CAUTION :
When adjusting belt tension, ap-
ply pressure at center of generator, never
against either end frame.
NOTE :
On a new vehicle, or after having in-
stalled new belts, check tension of belt(s) twice
in first 200 miles of operation. When making
adjustment, examine belt(s) and replace if neces-
sary .
A loose or broken drive belt will affect operation of
generator. A drive belt that is too tight will place too
much strain on bearings .
GENERATING SYSTEM
MAINTENANCE
Most charging system troubles show up as an
undercharged or overcharged battery. Since the bat-
tery itself may be defective, it should be checked first
to determine its condition. In the case of under-
charged battery, check for battery drain caused by
ground or by accessories being left on .
At regular intervals, inspect generating system to
locate and correct potential causes of trouble before
generating system performance is affected .
1 . Check generator drive belt tension and adjust
if necessary. See procedure earlier under "Generator
Drive Belt Tension Adjustment ."
2. Check generator mounting and adjusting arm
bolts and tighten as necessary.
3 . Check all electrical connections for tightness
and corrosion. Clean and tighten connections as
necessary. Be sure wiring insulation is in good condi
tion, and that all wiring is securely clipped to prevent
chafing the insulation .
4 . With engine running, listen for noise and check
generator for vibration. If generator is noisy or vi-
brates excessively, it should be removed for inspec-
tion and repair.
5. Check battery electrolyte level and specific
gravity . Replenish electrolyte level, as necessary.