GMC 1990 Light Truck Repair Manual page 337

The following notice applies to one or more steps in the assembly procedure of components in this portion of the
manual as indicated at appropriate locations by the terminology NOTICE: See 'Notice' on page 5-1 of this section.
N O T IC E : T h is fa s te n e r Is a n Im p o rta n t a tta c h in g p a rt In th a t It c o u ld a ffe c t th e p e rfo rm a n c e o f v ita l c o m p o n e n ts a n d
s y s te m s , a n d /o r c o u ld re s u lt In m a jo r re p a ir e x p e n s e , It m u s t b e re p la c e d w ith o n e o f th e s a m e p a rt n u m b e r o r w ith
a n e q u iv a le n t p a rt If re p la c e m e n t b e c o m e s n e c e s s a ry . D o n o t u s e a re p la c e m e n t p a rt o f le s s e r q u a lity o r s u b s titu te
d e s ig n . T o rq u e v a lu e s m u s t b e u s e d a s s p e c ifie d d u rin g re a s s e m b ly to a s s u re p ro p e r re te n tio n o f th is p a rt.
SUBJECT
Hydraulic Booster......................................................................................................................................... ........... 5- 1
Bendix Hydro-Boost................................................................................................................................................5- 1
Master Cylinders....................................................................................................................................................... 5 - 4
Composite Master Cylinder....................................................................................................................................5 - 4
Cast Iron Master Cylinder......................................................................................................................................5 - 4
Bendix Master Cylinder..........................................................................................................................................5- 6
Vacuum Boosters....................................................................................................................................................... 5 - 9
Single Diaphragm Vacuum Booster..........................................................................................................................5 - 9
Tandem Diaphragm Vacuum Booster.....................................................................................................................5-11
Specifications............................................................................................................................................................. 5-14
Special Tools............................................................................................................................................................. 5-15
BENDIX HYRDO-BOOST
Remove or Disconnect (Figure 1)
Bendix Hydro Boost Model has identifying information
stamped into the housing near the inlet line.
CAUTION: The accumulator
compressed gas. Always use proper tools and
follow recommended procedures or personal
injury may result. Do not apply heat to
accumulator. Do not attempt to repair an
inoperative accumulator, always replace with a
new accumulator. Dispose of an inoperative
accumulator by drilling a 1 /i e-inch diameter hole
through the end of the accumulator can
opposite the " O" ring.
Tools Required:
J 26889 Accumulator Compressor
• Place J 26889 over the end of the accumulator and
install a nut onto the stud (figure 2).
• Depress the accumulator with a C-clamp.
• Insert a punch into the hole on the housing.
1. Retainer (1).
• Release the C-clamp.
• Remove J 26889.
2. Accumulator (2) and O-ring (3).
3. Retainer (4).
4. Plug (5), O-ring (6) and spring (7) (figure 3).
SECTION 5
BRAKES
CONTENTS
HYDRAULIC BOOSTER
contains
K y | Clean
|Pl
5. Retainer (26).
6. Output pushrod (28), baffle (27), piston return spring
(25) and retainer (24).
• Saw off the eyelet of the pedal rod (20).
7. Boot (19).
8. Nut (18) and bracket (17).
9. Bolts (9).
• Separate the cover (16) from the housing (8).
10. Seals (14 and 15).
11. Piston assembly (22) and seal (23).
12. Spool valve (13).
13. Accumulator valve (11) (figure 4).
• Make a wire hook to aid in the removal.
14. Return line fitting (12) and seal (10).
• All the parts with power steering fluid.
Inspect
• Spool valve and spool valve bore for corrosion, nicks
and scoring. If found, replace the complete booster.
Discoloration of the spool or bore is not harmful and
is no cause for replacement.
• Housing and cover sealing surface for corrosion, or
nicks.
• Tube seat in the housing for burrs, nicks or
corrosion. Replace if needed (figures 5 and 6).
5-1
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