Check of serviceability of functioning / tightness, removal and installation of assembly of the vacuum amplifier of brakes

Functional check

1. Without starting the engine, depress the foot brake pedal several times. Check that there is no change in pedal back travel (distance between pedal and floor).

2. Keeping the pedal depressed, start the engine. If immediately after starting the pedal slightly «fails», therefore, the vacuum brake booster is working properly.

Leak test

1. Run the engine for a couple of minutes, then shut it off. Slowly depress the foot brake pedal several times. If at first the pedal stroke is gradually reduced with each squeeze, however, after three or four strokes it stabilizes, the tightness of the vacuum booster assembly is not broken.

2. Depress the foot brake pedal while the engine is running. Keeping the pedal depressed, stop the engine. If after 30 seconds of keeping the pedal depressed, its reserve stroke does not change, therefore, the tightness of the vacuum booster assembly is not broken, if necessary, check the operation of the check valve of the booster servo (see Removal, check of serviceability of functioning and installation of the check valve of the vacuum booster of brakes). On diesel models, check the vacuum pump for proper operation (see Check of serviceability of functioning of the vacuum pump of the servomotor of the brake booster (diesel models)). No violations are observed, replace the brake booster servo unit - the unit cannot be repaired and in case of failure it must be replaced as an assembly.

Removing

Models equipped with air conditioning

1. Discharge the cooling path in a specialized workshop.


2. Remove the air cleaner and intake ducts (see chapter Power and exhaust systems).

3. Remove the wiper motor (see chapter Onboard electrical equipment).

4. Remove generator (see chapter Engine electrical equipment).

5. Turn out fixing bolts and remove a basic arm of the generator from the inlet pipeline and a head of cylinders.

6. Remove GTZ (see Removal and installation of the main brake cylinder).

7. On models with 2.0L engines, remove the MAF sensor, disconnect the wiring and hoses, and remove the load pressure control solenoid valve.

8. Disconnect the vacuum tube from the amplifier or remove the check valve.

9. Remove the refrigerant tube fixing bolt on the rear bulkhead of the engine compartment behind the intake manifold and remove the expansion valve and inner seal.

This procedure should be carried out by refrigeration units in a car service workshop. If the system is opened for a long time, it must be isolated from the atmosphere until the time of refueling.

10. Remove the driver's footwell trim side panels. On the driver's side, disconnect the foot brake pedal return spring.

11. Remove the retainer and separate the pusher rod of the brake booster servo from the foot brake pedal. Remove the puck.

12. Give the upper left and lower right nuts securing the pedal bracket to the servo unit.

A — Left nuts of fastening of the vacuum booster of brakes

B - Right brake booster nuts

A.

B.

13. Remove the servo from the bulkhead of the engine compartment - try not to damage the brake pipes and other components located nearby. Remove the seal.

Models without air conditioning

Models with ABS

1. Remove the hydraulic modulator assembly (see Removal and installation of ABS and TCS components).

2. Remove the brake master cylinder (see Removal and installation of the main brake cylinder).

3. Turn out bolts of fastening of an arm of the hydromodulator.

4. Disconnect the vacuum tube from the amplifier or remove the check valve.

5. Remove the driver's footwell trim side panels and disconnect the foot brake pedal return spring.

6. Remove the retainer and separate the pusher rod of the brake booster servo from the foot brake pedal. Remove the puck.

7. Give the upper left and lower right nuts securing the pedal bracket to the servo unit.

8. Remove the servo from the bulkhead of the engine compartment - try not to damage the brake pipes and other components located nearby. Remove the seal.

Models without ABS

1. Remove the brake master cylinder (see Removal and installation of the main brake cylinder).

2. Disconnect the vacuum tube from the amplifier or remove the check valve.

3. Separate the relay stand from the support bracket and take it aside, remove the multi-pin connector from the bracket.

4. Give nuts of union connections of the brake pipes laid between the main cylinder and an adapter nozzle.

5. Place a cloth under the adapter and turn it inside out.

6. Remove the driver's footwell trim side panels and disconnect the foot brake pedal return spring.

7. Remove the retainer and separate the pusher rod of the brake booster servo from the foot brake pedal. Remove the puck.


8. Give the upper left and lower right nuts securing the pedal bracket to the servo unit.

9. Remove the servo from the bulkhead of the engine compartment - try not to damage the brake pipes and other components located nearby. Remove the seal.

Installation

Installation is carried out in the reverse order to the dismantling of the components.

1. Don't forget to replace the sealing gasket installed between the servo assembly and the bulkhead of the engine compartment. Make sure all fasteners are tightened to the correct torque.

2. Finally, bleed the brake system (see Bleeding the brake system), then start the engine and check the tightness of the vacuum line connections.