Chevrolet 1991 Light Duty Truck Repair Manual page 330

5-10 BRAKES
Delco Moraine NDH vacuum boosters have a build
date on a small paper label glued onto the front hous­
ing. The first digit indicates the Delco Moraine NDH
assembly line where it was built. The second digit indi­
cates the year it was built (a 0 means 1990 or a 1
means 1991). The last digits indicate the day it was
built. (Example: 271 would mean the 271st day of pro­
duction year.)
SINGLE DIAPHRAGM VACUUM
BOOSTER
E 3
Remove or Disconnect (Figures 20 and 21)
Tool Required:
J 23456 Power Brake Booster Disassembly and
Reassembly Fixture
1. Boot (1) and silencer (2).
2. Vacuum check valve (3) and grommet (4).
3. Front housing seal (5).
• Scribe a mark across the front and rear housings
to aid in reassembly.
• Use J 23456 to apply force in a counter clockwise
direction to unlock the housings (figure 21).
4. Return spring (9) and power piston group.
5. Power piston bearing (6) from the rear housing (7).
6. Reaction body retainer (25).
7. Piston rod (10) and reaction retainer (11).
8. Filter (12) using an awl or similar tool.
1.
Boot
2. Silencer
3 Vacuum check Valve
Grommet
4.
5. Front H ousing Seal
6. Power Piston Bearing
7. Rear Housing
8. Front H ousing
9. Return Spring
10. Piston Rod (Gaged)
11. Reaction Retainer
12. Filter
13. Diaphragm Retainer
Diaghragm
14.
15. Diaphragm Support
16. Power Piston and
Pushrod Assem bly
19. Pushrod
25. Reaction Body
Retainer
VACUUM BOOSTERS
Figure 20—Single Diaphragm Vacuum Booster Components
9. Power piston and pushrod assembly (16).
• Grasp the outside edge of the diaphragm sup­
port (15) and diaphragm (14).
• Hold the pushrod (19) down against a hard sur­
face.
• Use a slight force or impact to dislodge the
diaphragm retainer (13).
10. Diaphragm (14) from the diaphragm support (15).
|l?l
Inspect
• All parts for corrosion, nicks, cracks, cuts, scoring,
distortion or excessive wear. Replace parts as nec­
essary.
• Use crocus cloth to polish away minor corrosion of
the housings or diaphragm support.
Clean
■ i
• All parts, except the power piston and pushrod
in clean denatured alcohol.
assembly
• Dry all parts cleaned with dry, filtered and unlubri­
cated compressed air.
f»<*| Install or Connect (Figures 20 through 23)
Tools Required:
J 23456 Power Brake Booster Disassembly
and Reassembly Tool
J 28458 Power Piston Seal Protector
F5821