Audi A4

since 1994 of release

Repair and car operation



A4 Audi
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ exhaust System
- Cooling system
   So there is a cooling
   Check of level of cooling liquid
   Antifreeze check
   Check of system of cooling on tightness
   Radiator
   Locking cover of system of cooling
   Thermostat
   The help at malfunctions
   Water pump
   Maple belt of the water pump
   Various models of fans
   Vyazkostny fan
   The radiator fan with the electric drive
   Violations in operation of the fan of a radiator
   The help at malfunctions
+ Fuel tank and fuel pump
+ Air filter and absorption channels
+ injection System
+ Coupling
+ Transmission and main transfer
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tires
+ Electrotechnical equipment
+ ignition System
+ Lighting
+ Alarm equipment
+ Tools and devices
+ Heating and ventilation
+ body Details
+ Salon
Search of malfunctions
Technical characteristics





So there is a cooling

The water pump at the working engine constantly drives cooling liquid via numerous channels of cooling of the engine and thus takes away the warmth arising at the expense of combustion in cylinders. The pump accelerates a stream of cooling liquid by means of a lopastny wheel which is at it on a reverse side.

The drive of the water pump in the four-cylinder engine is provided with a maple belt, in the six-cylinder engine – a gear belt. What way the cooling liquid flows on uncountable hoses and channels, depends on its temperature at present.

  • If the engine is yet heated-up, cooling liquid moves on «a small contour» which goes via the engine and the heating heat exchanger. Depending on engine model the oil radiator in addition is connected to a small contour of circulation of cooling liquid.
  • At temperature over 87 °C the thermostat opens «a big contour» in which the radiator is connected.
  • If the temperature continues to raise further so, what even in an environment of a radiator reaches 82 °C, vyazkostny coupling of the fan of a radiator is switched to a rigid direct drive – the fan too rotates.
  • In cars with an electric drive of the fan of a radiator (climatic installation) the fan if in a radiator the temperature reaches about 92 °C is connected.

System of cooling of an elevated pressure

At working temperature in system of cooling there is an elevated pressure in 1,2–1,5 bar that considerably increases temperature of boiling of water – over 100 °C under usual conditions. Thus the reserve is created, the engine can reach working temperatures over 100 °C, and thus not «danger of boiling of liquid» in cooling system.

The correct pressure in system of cooling is provided with a locking cover of a broad tank in which there is a safety valve of an elevated pressure (about 1,2-1,5 bar) and a safety valve of the lowered pressure (0,06–0,1 bar).

The valve of the lowered pressure lets in an air stream if the temperature of cooling liquid goes down and, therefore, occupies smaller volume.

In a locking cover (1) system of cooling, on a jellied branch pipe (2) broad tanks settle down valves of the increased and lowered pressure. Sideways on a transparent tank there is a marking of level of liquid (3 and 4).