Audi A4

since 1994 release

Manual of the car

Audi A4
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ System of an exhaust
+ Cooling system
+ Fuel tank and fuel pump
+ Air filter and channels of absorption
+ System of injection
+ Coupling
+ Transmission and main transfer
+ Suspension bracket of wheels and steering
- Brakes
   Independent work on the brake system
   So the brake system works
   Check of brakes
   Brake fluid
   Check of level of brake fluid
   Check of the brake system on tightness and existence of damages
   Replacement of brake fluid
   Disk brakes
   Measurement of thickness of overlays of forward disk brakes
   Check of a condition of brake disks
   Replacement of overlays of disk brakes
   Back disk brakes
   Measurement of overlays of back disk brakes
   Emergency brake
   Check of idling of the lever of the emergency brake
   Main brake cylinder
   Brake amplifier
   Check of the brake amplifier
   Works on hydraulics of the brake system
   Pumping of the brake system
   The help at malfunctions
   ABS and EDS
   What does ABS?
   Function of separate knots
   Electronic system of distribution of brake effort (EBV)
   Violations in work of the ABS system
   Electronic blocking of differential (EDS)
+ Wheels and tires
+ Electrotechnical equipment
+ System of ignition
+ Lighting
+ Alarm equipment
+ Tools and devices
+ Heating and ventilation
+ Body details
+ Salon
Search of malfunctions
Technical characteristics


Check of the brake amplifier

Area around the brake amplifier with the engine of 1,6 l: 1 – a tank with brake fluid; 2 – brake amplifier; 3 – a vacuum tube from an inlet collector; 4 – the ejector for strengthening of the lowered pressure

The same look, as in the photo above, but with the six-cylinder engine: 1 – a tank with brake fluid; 2 – brake amplifier; 3 – a vacuum tube from an inlet collector; 4 – the returnable valve in a vacuum tube


  1. The engine has to be switched off.
  2. Press a pedal of a brake of 10 times.
  3. You hold a pedal wrung out and start the engine.
  4. If the brake amplifier is serviceable, then the pedal has to move a little. If the pedal does not fall, then the brake amplifier is faulty.
  5. At failure of the brake amplifier defect, most likely, is covered in system of the lowered pressure: the vacuum hose from an inlet collector to the brake amplifier is untight, the returnable valve in a vacuum hose, defect in a rubber ring between the main brake cylinder and the servo-driver or a membrane of the brake amplifier is untight.
  6. For check of the returnable valve remove a vacuum hose from the servo-driver.
  7. It is blown, suction is inadmissible.
  8. The returnable valve is on sale only together with a vacuum hose.
  9. To replace the damaged rubber ring between the main brake cylinder and the amplifier, it is necessary to dismantle the cylinder.
  10. In conclusion still defect of the most brake cylinder remains. In this case repair is impossible – it needs to be replaced.

Dismantle of the brake amplifier

For weakening of a rod of brake pressure upon pedals of a brake of Audi uses the special tool 3289. Unfortunately, it is impossible to do without this tool. Sequence of actions:


  1. Dismantle the main brake cylinder.
  2. Dismantle a vacuum hose.
  3. Unscrew two fixing bolts of the brake amplifier (TORX T45).
  4. Dismantle a pocket under the control panel at the left (the head Salon).
  5. Disconnect the switch of fires of stoplights and valves of ventilation of system of adjustment of speed on a brake pedal.
  6. Install the special tool 3289 on the brake pedal lever. Now it is possible to disconnect press a rod of the brake amplifier from a pedal (pull a pedal back).
  7. Take out the brake amplifier from a motive compartment.
  8. If the new brake amplifier is installed, then length of a rod of its management needs to be adjusted in the dismantled state.
  9. The distance between the end of a rod of management (it has to stand vertically) and an adjacent surface with two cut openings has to make 158,5 mm (the admission of 0,5 mm).
  10. After adjustment tighten a lock-nut.
  11. Before installation slightly grease a hinged finger.
  12. Use a new clamp for a hinged finger and new самоконтрящиеся nuts. Put a new sealing ring between the brake amplifier and the main brake cylinder.