Chevrolet 70 Series 1970, Service Manual

Page: 574 / 841

ENGINE ELECTRICAL 6Y-33
a fte r a se rv ic e p erio d of reaso n ab le length.
8 . If the re g u la to r cannot be ad justed to a
value within the sp ecified range, rep lace o r re p a ir
the re g u la to r.
NOTE: If re p eated re g u la to r fa ilu re s a r e ex­
p e rie n c e d on the vehicle, but no defects a r e found,
a sh o rted , grounded, o r open g en e rato r field wind­
ing, o r grounded lead s, of an in term itte n t n atu re
should be suspected.
TAILORING THE VOLTAGE SETTING
The p ro p e r setting is obtained when the b attery
re m a in s fully ch arged w ith a m inim um u se of w a te r.
If any c irc u it d efects a r e found, yet the b attery
re m a in s undercharged, r a is e the setting by 0.3
volts, then check the b a tte ry over a p e rio d of tim e
to see if im provem ents w e re achieved; r e s e t re g ­
u la to r if n e c e s sa ry . If the sy stem is overcharging,
low er the setting by 0.3 volts, then check b attery
o v er a p e rio d of tim e .
GENERATOR REPLACEMENT
Due to v a ria tio n s in design and equipm ent on
v eh icle s using A.C. g e n e ra to rs, the rep lacem en t
p ro c e d u re s w ill vary accordingly. The rem o val and
in stalla tio n in stru ctio n s given following a r e in­
tended only a s a guide. Additional operatio ns w ill
be re q u ire d on som e vehicles to rem ove other
equipm ent to p e rm it a c c e s s to g en e rato r, b elts,
a n d /o r b ra ck ets.
GENERATOR REMOVAL
1. D isconnect negative b attery cable from
b a tte ry .
CAUTION: It is important that bat­
tery negative terminal be disconnected,
since generator will be damaged if wiring
or terminals are accidentally shorted or
grounded while being disconnected.
2. On 4 2 -, 61-, and 62-am p g e n e ra to rs, de­
p r e s s lock on connector and pull connector out of
so cket on g e n e ra to r. P u ll ru b b e r boot off "BAT"
te rm in a l and rem ove te rm in a l nut. D isconnect w ire
fro m "GRD" te rm in a l and rem ove w iring clip.
On the 130-amp g en e rato r, rem ove nuts and
w a sh e rs fro m h a rn e ss lead s a t g e n e rato r te rm in ­
a ls . Rem ove h a rn e s s clip from g en e rato r, then pull
lead s fro m te rm in a ls.
3. Loosen adjusting a rm pivot bolt and g en e r­
a to r to mounting b ra c k e t b o lts. Move g e n e ra to r to
loosen d rive belt(s) and rem ove from g en e rato r
pulley.
4. Rem ove adjusting a rm pivot bolt and gen­
e r a to r to mounting b rack et bolts; then rem ove
g e n e ra to r.
GENERATOR INSTALLATION
IMPORTANT: Be s u re negative b a tte ry cable
is disconnected fro m b a tte ry . F a ilu re to disconnect
th e negative b a tte ry cable may re s u lt in dam age
to g e n e rato r.
1. A ttach g e n e ra to r to mounting b rack et and
in s ta ll adjusting a rm pivot bolt.
2. P la c e d rive belt(s) o ver g e n e ra to r drive
pulley and adjust b elt tension as explained under
"D rive B elt Tension A djustm ent" p rev iou sly . Tight­
en flange type lock nuts and mounting b olts to
to rq u e recom m ended in "S pecifications" a t end of
th is section.
3. On 42-, 61-, o r 62-am p g e n e ra to rs , push
the w iring h a rn e s s connector into socket, making
s u re lock on connector engages end fram e. P la c e
h a rn e ss clip on ground te rm in a l m arked "GRD"
and connect ground w ire to te rm in a l.
On the 130-amp g e n e rato r, connect h a rn e ss
lead s to re sp e c tiv e g e n e ra to r te rm in a ls, then in­
s ta ll attaching nuts and w a sh e rs. In stall h a rn e ss
clip.
4. A ttach re d w ire to "BAT" te rm in a l on gen­
e r a to r and fit boot o ver term in al.
5. P e rfo rm "G en erato r Output T e st" d escrib ed
previo u sly to d eterm in e if g e n e rato r is op eratin g
p ro p e rly and that re g u la to r is c o rre c tly adjusted.
GENERATOR BRUSH REPLACEMENT
NOTE: B ru sh rep lacem en t on 42-, 61-, and
130-amp g e n e rato r m odels re q u ire s p a rtia l d is ­
assem b ly of the g e n e ra to r and is co nsid ered a p a r t
of the unit overhaul p ro c ed u re .
Figure 17—G enerator Brush Replacement
(M odel 1117754) (Typical)
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL