Chevrolet DB90 Series, Руководство по обслуживанию

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S ec. 6K-91
w ash er. B olt (5) w ill support bracket a sse m b ly (9)
w hile starting bolts (3 and 6).
3. Install upper bolt and w asher (3), and two
sid e b olts and w a sh ers (6), but do not tighten b olts.
4. Install fan drive b elt (10) and adjust belt
ten sion as previou sly instructed. B olts (3 and 6)
should be threaded into bracket far enough to put
light p r e ssu r e on w a sh ers but m ust allow for m ove­
ment of bracket a ssem b ly (9) when adjusting bolt
(5) is turned.
5. When belt adjustm ent is co rr ect, tighten
upper bolt (3) to 85 to 105 foot-pounds, and tighten
two sid e bolts (6) to 35 to 45 foot-pounds torque.
FAN SUPPORT AND BELT
ADJUSTMENT (DP 9 0 MODELS)
F igu res 2 and 6 show fan installation and drive
for 12V-71 engine.
The pulley hub turns on a double row ball
bearing at the front and a sin g le row b all bearing
at the rear of hub (fig. 6). The bearings and the
cavity between the b earin gs are packed with g rea se
and should be lubricated a s outlined in the a s s e m ­
bly procedure.
DISASSEMBLY (R efer to F ig. 6)
1. R em ove the fan blade and sp acer by taking
out s ix mounting b o lts, nuts, and w a sh ers.
2. F ree the fan b elts by loosening the adjust­
ing bolt and bracket b olts.
3. R em ove the bracket bolts and detach the
hub and bracket assem b ly .
4. R em ove the hub cap, then take out the cotter
pin and rem ove the nut. If the bearings are to be
EN G IN E C O O L IN G SYSTEM
rem oved, take out the retaining ring.
5. Support the hub, front face up, on wooden
b lock s high enough to allow the bracket to be r e ­
m oved. Tap the fan shaft with a p la stic ham m er to
fr e e the fan shaft and bracket assem b ly from the
b earings in the hub.
6. Rem ove the ball b earings from the pulley
hub a s follow s:
a. Support the pulley hub, rear face up, on two
wood b lock s, spaced far enough apart to perm it the
rem oval of the bearing from the hub.
b. Tap the front bearing out of the hub by tap­
ping alternately around the rea r face of the bearing
outer race with a sm a ll b ra ss rod and ham m er.
c. R e v e r se the pulley hub on the two wood
block s and rem ove the rear bearing from the hub
in the sam e manner.
INSPECTION
1. Clean the fan and rela ted p arts with clean
fuel o il, and dry them with co m p ressed a ir . Shield­
ed b earings must not be washed; dirt may be w ash­
ed in and the cleaning fluid could not be entirely
rem oved from the bearing.
2. Exam ine the b earings for any indications
of corro sio n or pitting. Hold the inner race or
cone so it does not turn and revolve the outer race
o r cup slow ly by hand. If rough sp ots a re found,
rep lace the b earings.
3. Check the fan blades; if blades are cracked
o r bent, rep lace them . Look for crack s in the ad­
justing and support bracket ca stin g s.
4. When replacem ent of either the fan shaft or
adjusting bracket is n e c e ssa r y , a new fan shaft and
bracket a ssem b ly must be used .
Figure 6 —Fan Support, P ulley, and Fan I I
2
V-71 Diesel Engine)
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT