Removal
- Disconnect the wires from the battery terminals and remove the battery from the vehicle.
- Remove the main brake cylinder from the vacuum brake booster and attach the reservoir to the main brake cylinder with a plastic clamp.
- Disconnect the vacuum hose from the brake booster.
Inside the car
- Remove the pin and disconnect the pushrod from the brake pedal.
Vehicles with F engine
Under the car
- Disconnect the 2 holders on the vacuum booster bracket and 1 holder on the shock absorber strut spring cup and release the wiring harness.
- Unscrew nuts 1,2 and 3 (pic. 12.19) mounting of the vacuum brake booster.
In the engine compartment
- Remove the air filter assembly.
- Disconnect the clutch cable from the engine bracket and remove the clamp. Pass the cable behind the vacuum brake booster.
- If necessary, to access nut 4 (pic. 12.19) securing the vacuum brake booster, release the heater radiator hoses from the clamps and move them to the side.
- Head Fre. 1396 with a ratchet, unscrew nut 4 (pic. 12.19) mounting of the vacuum brake booster.
- Remove the vacuum brake booster.
Cars with Z engine
Under the car
- Disconnect the 2 holders on the vacuum booster bracket and 1 holder on the shock absorber strut spring cup and release the wiring harness.
- To access the vacuum booster mounting nuts, remove the exhaust pipes from the exhaust manifold to the catalytic converter and the exhaust pipe heat shield. Disconnect the connector from the vehicle speed sensor located on the transmission.
- Unscrew nuts 1,2 and 3 (pic. 19) mounting of the vacuum brake booster.
In the engine compartment
- Remove the air filter cover and filter element, then insert a piece of cloth into the air duct opening.
- Remove the bracket on the throttle assembly that holds the throttle cable sheath stop
- If necessary, to access nut 4 (pic. 12.19) securing the vacuum brake booster, release the heater radiator hoses from the clamps and move them to the side.
Pic. 12.19. Location of the brake booster mounting nuts
- Head Fre. 1396 with a ratchet, unscrew nut 4 (pic. 12.19) mounting of the vacuum brake booster.
- Remove the vacuum brake booster.
Vehicles with G engine
Under the car
- Disconnect the 2 holders on the vacuum booster bracket and 1 holder on the shock absorber strut spring cup and release the wiring harness.
- Unscrew nuts 1.2 and 3 (pic. 12.19) mounting of the vacuum brake booster.
In the engine compartment
- Remove the air filter assembly, the air supply line to the exhaust manifold and the air outlet line from the turbocharger.
- If necessary, to access nut 4 (pic. 12.19) securing the vacuum brake booster, release the heater radiator hoses from the clamps and move them to the side.
- Head Fre. 1396 with a ratchet, unscrew nut 4 (pic. 12.19) mounting of the vacuum brake booster.
- Remove the vacuum brake booster.
Installation
- Before installing the brake master cylinder, check the distance to the pushrod «X», which should be 22.3 mm. If necessary, adjust the protrusion by turning the adjusting bolt.
- Check the rod length «U», which for Z-G8T engines should be 193.5 mm, and for F engines - 198.5 mm (rice. 12.18). To adjust and set the required rod length, rotate the fork at its end.
- Before installing the vacuum booster studs into the bracket, check that the bellows are positioned correctly.
- Install the brake master cylinder.
- If the brake master cylinder was removed, bleed the brake system
- Check the vacuum brake booster for leaks.
- Connect a pressure gauge with extension tube and T-piece between the brake booster and vacuum source (vacuum pump on vehicles with diesel engines and intake manifold on vehicles with gasoline engines).
- Start the engine and let it idle for one minute.
- Using a clamp, clamp the flexible vacuum hose in place «A» (pic. 12.20) and turn off the engine.
- If within 15 s the vacuum decreases by more than 33 mbar from the initial one:
- check the condition of the gasket between the main brake cylinder and the vacuum brake booster;
- check the one-way valve of the vacuum brake booster and, if necessary, replace it;
- check the diaphragm and. if necessary, replace the vacuum brake booster.
Pic. 12.20. Checking the vacuum brake booster for leaks: A - place where the flexible vacuum hose is pinched