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
   Locking cover of system of cooling
   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

The help at malfunctions


A.Temperatura rises slowly, the operational temperature is reached later, insufficient effect on -
The Klapanny plate of the thermostat is blocked in situation "openly" (German «Оffen») (for example, because of a deposit); the liquid stream to a radiator is constantly open. The engine too long works in not heated-up condition. But for the small period of time it does not put harm. Despite it, change the thermostat somewhat quicker.
B. The arrow of the indicator of temperature is rejected to the right to a limit, despite the correct level of cooling liquid, the control bulb of cooling liquid blinks. A radiator and the bottom hose going to a radiator, cold.  The Klapanny plate of the thermostat is blocked in situation «Geschlossen») (for example, because of a defective or not tight box of the thermostat) "is closed" (German. At all do not continue a trip, differently there will be heavy thermal damages of the engine! At once replace the thermostat.

 Council: If on the way the engine begins to boil because of the defective thermostat, towage or complete dismantle of the thermostat on a place will help only. If you made the decision to dismantle the thermostat, in the beginning should wait, the temperature of cooling liquid will not go down yet.

Four-cylinder engine: here the internal device of the water pump and the thermostat (in a cut) is shown. The lopastny wheel (1) water pump is well visible. Nearby there is a thermostat (2).

On the right: at the six-cylinder engine the case of the thermostat (shooter) is on the right ahead at the engine block.

At the left: in drawing assembly position of the thermostat is shown at the four-cylinder engine. The air valve (shooter) should be turned up.

Thermostat dismantle

The jammed thermostat is very difficult for dismantling on the way. It is located quite far below therefore it is necessary to merge almost all cooling liquid. Besides at the hot engine will pass a lot of time before you can begin work, without being afraid thus to burn hands. At installation of the new thermostat it is necessary to replace also sealing ring on the case of the thermostat and the water pump.


  1. For all models: completely merge cooling liquid.
  2. Four-cylinder engine: dismantle the bottom facing of an impellent compartment (head of the Detail of a body).
  3. Unscrew below on the case of the water pump a hose (that already became for plum of cooling liquid).
  4. Unscrew two bolts below on a cover of the case of the thermostat.
  5. Uncover also the thermostat.
  6. Six-cylinder engine: remove maple a belt, dismantle the tension device.
  7. Dismantle a cover of a gear belt (head Engines). The gear belt remains on a place.
  8. Dismantle a hose of supply of cooling liquid to a radiator below on a branch pipe for a hose on the thermostat case.
  9. Unscrew two bolts on a cover of the case of the thermostat.
  10. Carefully lift a gear belt over a crossing point of the case of the thermostat, remove the case.
  11. Take out the thermostat.
  12. For all models: at installation of the new thermostat its small sealing plate should be turned to the engine.
  13. Only for the six-cylinder engine: the air valve in an external ring of the thermostat should be turned up.
  14. Replace a sealing ring.
  15. Tighten bolts on the case of the thermostat and the water pump with the moment of an inhaling of 10 Nanometers.

Thermostat check

By means of the built-in thermometer you can check, whether the thermostat opens at the set temperature.

Opening beginning
Opening end
Minute opening course
About 87 °C
About 102 °C
About 8 mines


  1. Dismantle the thermostat.
  2. Suspend the thermostat in capacity with water and warm up water.
  3. Check, whether the klapanny plate in a saddle rises at achievement of temperature of 87 °C.
  4. At this check the end of opening can be reached not completely (as it is known, water in open capacity boils approximately at 100 °C), but nevertheless it is visible, whether the thermostat opens more strongly.
  5. But the total length of a course of opening is almost reached. But that is visible, already enough, to define defective thermostat.
  6. At the slightest doubt in serviceability of the thermostat replace it.