Bleeding the brake system (Audi A4 B6)

After repairing the brake system, during which it was opened, air may enter the system. In this case, air must be removed from the system. A sign of the presence of air in the system pipes is the pliability of the brake pedal when pressing it. In this case, it is necessary to eliminate the leak and remove air from the system.

At the service station, the brake system is usually filled with liquid, and the air is removed from it using a special device.

Warning: When using the specified device, the filling pressure of the system must not exceed 1 atm. This operation can also be carried out without the specified device. In this case, air is removed from the brake system by rocking movements of the brake pedal, which requires the help of an assistant.

If air has entered any individual brake cylinder, it is necessary to bleed the entire brake system and thus each wheel cylinder. If only one caliper is being replaced or repaired, it is usually sufficient to bleed the corresponding brake cylinder.

Safety Note

If one of the chambers of the brake fluid reservoir is completely empty (for example, if there is a leak in the brake system or if you forgot to add fluid to the reservoir when removing air), air is sucked into the system and enters the ABS pump. In this case, air from the brake system must be removed at a service station using a special device.

The bleeding sequence is: rear right brake, rear left brake, front right and front left brake and clutch slave cylinder.