Audi A4

Since 1994 of release

Repair and car operation

Audi А4
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ Exhaust system
- Cooling system
   So there is a cooling
   Check of level of a cooling liquid
   Antifreeze check
   Check of system of cooling on tightness
   Zapornaja cover of system of cooling
   The thermostat
   The help at malfunctions
   The water pump
   Klinovoj belt of the water pump
   Various models of fans
   The vjazkostnyj fan
   The fan of a radiator with the electric drive
   Infringements in work of the fan of a radiator
   The help at malfunctions
+ 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
+ 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

Zapornaja cover of system of cooling

In system of circulation of a cooling liquid under pressure запорная the cover plays the important role a broad tank:

  • The sealing surface of the screwed up cover strong nestles on edge of an aperture of a broad tank. Pressure cannot go down.
  • If at heating pressure in cooling system exceeds 1,2–1,5 bar, the valve of adjustment of an elevated pressure opens. Levelling pressure, there can be a little water steam.
  • At cooling the liquid is again compressed, and in cooling system there is a lowered pressure. For alignment of the lowered pressure in a cover there is a second valve. It opens at the lowered pressure in 0,06-0,1 bar, and atmospheric air can get into a broad tank.

Check of valves of the raised and lowered pressure by make-shifts

The one who does not wish to spend effort to check, can simply replace rather inexpensive cover. In a workshop it check a manometre:


  1. Pump up pressure.
  2. At pressure 1,2–1,5 bar the valve should open.
  3. At the removed cover compress a thick hose of giving of a liquid.
  4. Put on and screw up a cover, release a hose.
  5. Release a hose.
  6. If the compressed hose again is approximated, the valve is perfectly in order.
  7. If in the mornings before the first start-up hoses of giving of a cooling liquid are flattened, the valve of the lowered pressure for certain is not perfectly in order.