Service of Audi A4 from 2001 to 2005 release.
1. Operation and maintenance of the car
2. Engine
3. Transmission
4. Running gear
5. Steering mechanism
6. Brake system
6.1. Preliminary checks
6.1.1. Brake disks
6.1.2. Check of the brake system
6.1.3. Replacement of brake fluid
6.1.4. Visual check of the brake system on existence of leakage and damages
6.1.5. Check of thickness of brake slips
6.1.6. Check at high and with a low pressure
6.1.7. Check of residual pressure
6.1.8. Troubleshooting at unilateral wear of a brake shoe
6.1.9. Check of the main brake cylinder
6.1.10. Pumping of the brake system
6.1.11. Process of removal of air for cars with electronic system of maintenance of course stability (ESP)
6.2. Repair of the brake system
6.3. Repair of brakes of forward wheels
6.4. ABS system
6.5. Tables
7. Onboard electric equipment
8. Body
9. Schemes of electric equipment


6.1.2. Check of the brake system

General provisions

Fig. 6.1. Chart of change of density of brake fluid

With increase in content of water boiling temperature goes down, i.e. at strong heating of brake fluid there can be a formation of bubbles of steam and refusal of a brake (fig. 6.1).

Brake fluid is hygroscopic, i.e. it is capable to absorb water and moisture from air

Brake fluid darkens eventually. Dark color of brake fluid does not testify to its quality. Change of color arises because of chemical reactions, and it can happen, especially at cars to ABS, already later short time (several weeks).

Rubber parts of the brake system (a cuff, manzhetny consolidations) are susceptible to influence of mineral oils, gasoline and cleaners.

Fig. 6.2. A difference between the normal and "moistened" cuff: A – a cuff – the original size; B – the cuff – when wetting by mineral oil inflates

Already their smallest quantity on manzhetny consolidation or a cuff leads to change of details, and can worsen functioning of a brake. Consequences of the polluted brake system affect only several months later, and then demand considerable expenses, from cars with ABS (fig. 6.2).
It is necessary to store containers with brake fluid always well closed. Only thus the possibility of hit of oil, dirt or cleaner, and also moisture is excluded from air.
To store packings with brake fluid separately from oil (and also hydraulic oil) and liquids for cleaning completely to exclude mixing of two liquids or even wrong gas station of the brake system.

6.1.1. Brake disks

6.1.3. Replacement of brake fluid