Chevrolet 70 Series 1970, Service Manual

Page: 479 / 841

ENGINE COOLING SYSTEM 6K-12
p e rta in s to a ll o th e r engines using oil coo ler.
Models equipped -with oil cooler u se the type
of oil cooling sy stem shown in figure 16. Oil is
filte re d , circ u lated through oil coo ler, and re tu rn ­
ed to engine.
If engine d ifficulties a r e encountered and th e re
is suspicion that foreign m a tte r has en tered the
oil coo ler, the oil coo ler and connecting lin es m ust
be flushed before engine is put back into operation.
Oil cooler, located at bottom of ra d ia to r co re,
should be flushed in the following m anner:
1. D isconnect oil coo ler lines at oil filte r.
2. B ack-flush oil coo ler and lin es using clean
solvent and co m p ressed a ir . DO NOT EXCEED
100 PSI AIR PRESSURE.
3. Rem ove a ll rem aining cleaning solvent from
the sy ste m with co m p re ssed a ir.
4. F lush sy ste m again with the sam e type of
oil norm ally circ u la te d through the cooler.
5. T est flow of oil through coo ler. If flow is
not r e s tr ic te d , reconnect oil co oler lin es. If flow
is r e s tr ic te d , have oil cooler elem ent re p la ced by
a ra d ia to r s p e c ia list.
FAN AND DRIVE BELTS
DRIVE BELT TENSION ADJUSTMENT
D rive b e lts m ust be kept at p ro p e r tension. A
loose o r broken d riv e b elt will affect operation of
driven a c c e sso ry . A drive b elt that is too tight will
place ex c essiv e s tr e s s on the bearings within the
driven a c c e sso ry .
V -B elt Tension
F an b elt tension on vehicles equipped with V-
b elts should be adjusted to 120-130 pounds on new
b elts, using (J-23573) b elt tension gauge. Used
d riv e b elts should be adjusted to 80-90 pounds.
Gauge should be placed a t the ce n te r of the g re a t­
e st span.
Figure 16—O il Cooler Circuit I A ll
Engines Except D etroit Diesel)
Figure 17—Using Poly-V Belt Tension Gauge
P oly-V B elt Tension
Fan b elt tension on vehicles equipped with
P oly-V b elts should be adjusted using (J-23586)
b elt tension gauge, a s shown in fig ure 17. Gauge
should be placed at c e n te r of longest b elt span to
obtain p ro p e r reading. When adjusting a new drive
belt, ad ju st tension to "NEW" b elt specification,
tu rn engine o v er s e v e ra l tim e s, then re s e t b elt
tension to "NEW" b elt specification.
NOTE: A Poly-V b elt is co nsid ered USED a fte r
l - h o u r 's operation o r approxim ately 50 m iles
driving tim e.
Poly-V b elt tension sp ecification s a r e as
follows:
PI, FI 90
P ow er S teering Pump - New 103# -■
113#
- Used
78# -■ 88#
G en erato r - New 44# -• 54#
- Used 29# -■
39#
A ir Conditioning C o m p re s s o r- New 84# -■ 94#
- U sed 64#
74#
F an D rive - New 2 5 5 # -• 265#
- Used 235# -• 245#
DH, FH 90
G e n erato r
- New
84# - 94#
- Used 64# - 74#
DRIVE BELT REPLACEMENT
On som e v ehicles, s e v e ra l a c c e s s o rie s may
be driven fro m m ultiple groove crankshaft pulley,
and the rep lacem en t of any one inside d rive belt
w ill m ake it n e c e ssa ry to rem ove a ll the outside
b e lts firs t.
NOTE: Instruction s fo r replacing pow er s t e e r ­
ing drive b elt a r e given in "POWER STEERING"
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL