Power Brake Booster

REMOVAL & INSTALLATION

1990–94 Vehicles

1. Disconnect the negative battery cable. Siphon the brake fluid from the master cylinder reservoir.
2. Remove and relocate the air conditioning relay box and the solenoid valve located at the power brake unit.
3. Disconnect the vacuum hose from the booster by pulling it straight off. Prying off the vacuum hose could damage the check valve installed in the brake booster vacuum hose.
4. Detach the electrical harness connector from the brake level sensor.
5. Remove the nuts attaching the master cylinder to the booster and remove the master cylinder and position aside. If necessary, disconnect and plug the brake fluid lines at the master cylinder.
6. From inside the passenger compartment, remove the cotter pin and clevis pin that secures the booster pushrod to the brake pedal.
7. From inside the vehicle, remove the nuts that attach the booster to the dash panel. Remove the brake booster from the engine compartment.

   Fig. 1: Exploded view of the power brake booster and related components — 1990–94 vehicles

   To install:

8. Install the brake booster to the dash panel. From inside the vehicle, install the attaching nuts and tighten to 12 ft. lbs. (17 Nm).
9. Apply grease to the clevis pin and install with washers in place. Install new cotter pin and bend to secure in place.
10. Attach the vacuum hose to the booster fitting.
11. Install the master cylinder assembly to the mounting studs on the brake booster. Install the master cylinder mounting nuts and tighten to 9 ft. lbs. (12 Nm).
12. Reconnect the brake fluid reservoir to the master cylinder, if disconnected. Attach the electrical connector to the brake fluid level sensor.
13. Install the solenoid valve assembly and the relay box, if removed. Connect the negative battery cable.
14. Add fluid to the brake fluid reservoir as required. Bleed the master cylinder. If after bleeding the master cylinder the brake pedal feels soft, bleed the brake system at all wheels.
15. Check the brake system for proper operation.

1995–98 Vehicles

1. Disconnect the negative battery cable. Siphon the brake fluid from the master cylinder reservoir.
2. Remove the master cylinder, as outlined earlier in this section.
3. Disconnect the vacuum hose (with the built-in check valve).
4. Unfasten the brake line fitting.
5. From inside the vehicle, perform the following:
   1. Remove the brake pedal return spring.
   2. Remove the snap pin.
   3. Remove the washer.
   4. Unfasten the clevis pin.

      NOTE: On 2.0L turbo and 2.4l engines, you must slide the engine forward to remove the brake booster from the body.

6. Unfasten the retaining bolts, then remove the brake booster. Once the booster is removed, remove the sealer.

   To install:

7. Installation is the reverse of the removal procedure. Make sure the lubricate the components shown in the accompanying figure.

   Fig. 2: Brake booster component grease fitting locations

8. When attaching the vacuum hose, connect the hose to the nipple as shown in the accompanying figure. Secure the hose with the clip. Make sure the check valve and the pipe part of the brake booster do not contact each other. When connecting, make sure the markings face upwards. Install the other end of the vacuum hose fully onto its port on the engine. Use the retaining clamp to secure the hose.

   Fig. 3: You must obtain the proper clearances when attaching the vacuum hose

9. Make sure to adjust the clearance adjustment between the brake booster pushrod and the primary piston, as follows:
   1. Calculate the clearance A from the B, C and D measurements, as shown in the accompanying figure. A equals B minus C minus D.
   2. The clearance should be 0.256–0.335 in. (0.65–0.858mm). When brake booster negative pressure 9.7 psi (67 kPa) is applied, then clearance value will become 0.004–0.012 in. (0.1–0.3mm).
10. Install the master cylinder, as outlined earlier in this section.