Audi 80/Avant (B4)

since 1991-1995 of release

Repair and car operation



Audi 80/Avant
+ Technical specification
+ Engines
+ System of production of the fulfilled gases
+ cooling System
+ Fuel tank and fuel pump
+ Air filter and airintaking channels
+ injection System
+ Coupling
+ Transmission and transmission
+ Suspension bracket and steering
- Brake system
   Check of brake mechanisms
   Brake liquid
   Check of level of brake liquid
   Check of tightness of brake system
   Replacement of brake liquid
   Disk brake mechanisms
   Measurement of thickness of blocks of the disk mechanism
   Control of a condition of brake disks
   Replacement of blocks of disk brake mechanisms
   Drum-type brake mechanism
   Measurement of brake shoes of the drum-type mechanism
   Check of a course of a pedal of a brake
   Disk brake mechanism of back wheels
   Measurement of thickness of blocks of back disk brakes
   Check of a free wheeling of the lever of the parking brake
   Main brake cylinder
   Amplifier of brakes
   Check of the amplifier of brakes
   Regulator of brake forces
   Repair of a hydraulic drive of brakes
   Pumping of brake system
   List of malfunctions
+ Anti-blocking system of brakes
+ Wheels and tires
+ Body electrosystem
+ ignition System
+ Lighting
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ body Elements
+ Search of malfunctions
+ Specifications





Brake liquid

This yellowish – and, by the way, poisonous and aggressive in relation to an autovarnish – liquid does not corrode rubber and metal parts. It remains even at a minus 40°С still rather fluid, and its boiling point is located, despite the mentioned fluidity, on 260°С.

But brake liquid possesses also one very unpleasant property: it easily absorbs water, it "is hygroscopic". Water can really get to brake liquid, for example through humidity of air: through a compensatory tank, and also microscopic not tight places on hoses of brake system and rubber cuffs. Complete absorption of water, however, does not lead to corrosion of metal parts of system, but to strong decrease in a boiling point. At only 2,5 % of the content of water the boiling point is already only on 150°С.

It is dangerous at high load of brakes because in this case they strongly heat up. Near the warmed-up brakes in working liquid air vials can be formed. As air is compressed – the brake pedal will fail in a floor! Only fast "podkachivaniye" a brake pedal in this case can help. Especially dangerously this effect is shown when braking car after strong load of brakes. Because of absence обдува a counter flow elements of brakes heat up even more strongly; the greatest temperature is reached approximately after 15 mines of parking. Only half an hour later the temperature of brake liquid again falls to the normal. Therefore the servicing plan preventively orders replacement of brake liquid each two years.

Brake liquid should correspond to the FMVSS116DOT4 standard. All liquids marked thus without fears can be mixed one with another.