SECTION 4C
POWER BOOSTER
SPECIFICATIONS
Fastener Tightening Specifications
Application | N•m | Lb-Ft | Lb-In |
Booster-to-Dash Panel Nuts | 22 | 16 | - |
DIAGNOSIS
Power Booster Test
- With the engine off, eliminate vacuum in the boosterby pumping the brake pedal several times.
- Push the pedal down and hold it in this position.
- Start the engine.
- The booster is OK if the pedal drops further becauseof the extra force produced.
If the brake pedal does not drop, the vacuum system(vacuum hoses, check valve, etc.) is probably defectiveand should be checked.
If no defect is found by checking the vacuum system,the defect is in the booster itself.
MAINTENANCE AND REPAIR
ON-VEHICLE SERVICE
Vacuum Hose
Removal Procedure
- Remove the clip on the vacuum hose connection atthe brake booster.
- Remove the hose from the brake booster.
- Remove the clip on the vacuum hose connection atthe intake manifold.
- Remove the vacuum hose.
Installation Procedure
- Mount the vacuum hose and ensure the connectionsare tight on each end.
- Install the vacuum hose clips.
- Check the function of the booster. Refer to the "PowerBooster Test" in this section.
Power Booster Assembly
Removal Procedure
- Remove the master cylinder. Refer to Section 4B,Master Cylinder.
- Remove the clamp on the vacuum hose connectionto the booster.
- Remove the vacuum hose from the booster. Refer to "Vacuum Hose" in this section.
- Disconnect the retaining clip from the pushrod of brake booster.
- Remove the booster mounting nuts from the studsprotruding from the dash panel, and remove thebooster.
Installation Procedure
- Install the booster and the mounting nuts to the dashpanel.
Tighten
Tighten the booster-to-dash panel nuts to 22 N•m(16 lb-ft).
- Install the master cylinder onto the booster. Refer to Section 4B,Master Cylinder.
- Install the new vacuum hose. Refer to "Vacuum Hose"in this section.
- Connect the retaining clip to the pushrod of brake booster.
- Check the function of the booster. Refer to "Power Booster Test" in this section.
GENERAL DESCRIPTIONAND SYSTEM OPERATION
Power Booster
The power booster is a dual-diaphragm, vacuum-suspendedunit. In normal operating mode, with the servicebrakes in the release position, a vacuum-suspendedbooster operates with a vacuum on both sides of its diaphragm. When the brakes are applied, air at atmosphericpressure is admitted to one side of thediaphragm to provide the power assist. When the brakesare released, atmospheric air is shut off from that side ofthe diaphragm. The air is then drawn from the boosterthrough the vacuumcheck valve by the vacuumsource.
Important : If any hydraulic component is removed ordisconnected, it may be necessary to bleed all or part ofthe brake system. Refer to Section 4A, Hydraulic Brakes. 
