Audi S4

since 2000 release

Repair and operation of the car



Audi S4
+ Introduction
+ Governing bodies and methods of safe operation
+ Current leaving and service
+ Engine
- Cooling systems, heating and air conditioner
   - Cooling system
      General information
      Antifreeze - a security measure from freezing
      Replacement of cooling liquid
      Removal and installation of the thermostat
      Check of the thermostat
      Replacement of hoses of the cooling system
      Removal and installation of a radiator
      Removal and installation of the fan of a radiator
      Removal and installation of the pump of cooling liquid
   + Systems of ventilation, heating and air conditioning
+ Power supply systems, release and decrease in toxicity of the fulfilled gases
+ Systems of electric equipment of the engine
+ Manual box of gear shifting
+ Automatic transmission
+ Coupling, power shafts and differential
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment





Cooling system

General information

Scheme of connections of hoses of the cooling system

1 — a heater Radiator
2 — the OZh Pipeline lower
3 — the Broad tank
4 — the Oil cooler
5 — the Inlet pipeline
6 — Nizhny Novgorod a radiator hose
7 — the Top hose of a radiator

8 — the Radiator
9 — the OZh Pipeline top
10 — the Water pump with the thermostat
11 — the Turbocompressor
12 — the Block and a head of cylinders
13 — the Output union

On some models the system of regulation of temperature of cooling liquid working according to the characteristic put in the control unit is applied. In comparison with the ordinary cooling system such system increases thermodynamic efficiency of the engine and thus optimizes the characteristic of torque.

The cooling system working according to the set characteristic consists of the distributor of cooling liquid with the thermostat, an electric heating element, and also springs, for mechanical locking of channels of cooling liquid.

By means of the warmed-up thermostat temperature of cooling liquid is regulated by the control unit of the engine according to the characteristic put in it. At the same time temperature, optimum from the point of view of the given engine capacity is maintained.

For example, at full loading of the engine the extending element heats up and thus the thermostat opens more. Thereby temperature of cooling liquid decreases that leads to more intensive cooling of combustion chambers. Colder combustion chambers lead to earlier ignition and by that to increase in torque of the engine.

Cooling liquid goes through a radiator constantly working pump. Liquid passes through a radiator from top to down and is cooled with the air passing through it. The fan of cooling liquid with the electric drive is used.

Heater and ventilation

The heater consists of the fans and heat exchangers located in blocks of forward and back parts of salon. Hot cooling liquid passes through heat exchangers. When moving the handle of management of the modes of a heater located on the control panel valves open, and hot air begins to come to interior of the car. If to turn on the heater fan, air will move in salon forcibly.

Intaking air before getting to salon, passes through the filter (address the Head the Current leaving and service). The main share of particles of dust will settle in the filter. It is necessary to observe frequency of replacement of the filter. The filter littered by dust will limit air supply in salon that will lead to an air stagnation in salon.

Distribution of streams of air of system of ventilation is carried out by means of gates. The air circulation mode is provided. Gates are run by servo-drivers.