Audi A4

Since 1994 of release

Repair and car operation



Audi А4
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ Exhaust system
+ Cooling system
+ Fuel tank and the fuel pump
+ The air filter and channels всасывания
+ Injection system
+ Coupling
+ Transmission and the main transfer
+ Suspension bracket of wheels and steering
- Brakes
   Independent work on brake system
   So the brake system works
   Check of brakes
   Brake liquid
   Check of level of a brake liquid
   Check of brake system on tightness and presence of damages
   Replacement of a brake liquid
   Disk brakes
   Measurement of a 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
   Manual brake
   Check of idling of the lever of a manual brake
   The main brake cylinder
   The brake amplifier
   Check of the brake amplifier
   Works on hydraulics of brake system
   Prorolling of brake system
   The help at malfunctions
   ABS and EDS
   What does ABS?
   Function of separate knots
   Electronic system of distribution of brake effort (EBV)
   Infringements in system ABS work
   Electronic blocking of differential (EDS)
+ Wheels and tyres
+ The electrotechnical equipment
+ Ignition system
+ Illumination
+ The alarm equipment
+ Tools and devices
+ Heating and ventilation
+ Body details
+ Salon
Search of malfunctions
Technical characteristics



Brake liquid

Between an impellent compartment and a windscreen in so-called влагоулавливающей to a box take places a tank with a brake liquid (1), the main brake cylinder (2) and the brake amplifier (3). In a photo marks of level of filling of a tank "MOVE" and «MIN» are well visible.

This yellowish, poisonous and aggressive in relation to an automobile varnish a liquid does not corrode metal and rubber details. She remains enough жидкотекучей at–40 °С and, despite the жидкотекучесть, possesses extremely high boiling point approximately nearby 260 °С.

But the brake liquid possesses very unpleasant property: it willingly absorbs water, it «гигроскопична». Water, for example at the expense of humidity of atmospheric air, can really get into a brake liquid: through a broad tank or through microscopic not tight sites in brake hoses or in rubber cuffs. Such впитывание waters results not only in corrosion of metal details of brake system, but also causes fast fall of a boiling point of a brake liquid. At the water maintenance of all in 2,5 % its boiling point is only at 150 °С. Close разогретых brakes steam vials in a hydraulic liquid can be formed. They are compressed – the brake pedal can deeply fail, sometimes the foot presses simply in emptiness! In this case fast prorolling of a liquid by a brake pedal sometimes helps. This effect is especially dangerous at a stop of the car after strong loading on brakes. Because of a head wind lack everything which are in an environment of brakes, is warmed up even more strongly. And approximately only in half an hour the temperature of a brake liquid goes down to the normal.

Therefore the maintenance service plan orders preventive replacement of a brake liquid every two year. The brake liquid should correspond to specification FMVSS 116 DOT 4. With such designation it is possible without fear to mix all liquids.