Audi 80/Avant (B4)

since 1991-1995 release

Repair and operation of the car

Audi 80/Avant
+ Technical specification
+ Engines
+ System of production of the fulfilled gases
- Cooling system
   Check of level of cooling liquid
   Frost resistance check
   Check of the cooling system on tightness
   Carving cover of a broad tank
   List of malfunctions
   Water pump
   Maple belt of the water pump
   Cooling system fan
   Malfunctions of the fan of the cooling system
   List of malfunctions
+ Fuel tank and fuel pump
+ Air filter and airintaking channels
+ System of injection
+ Coupling
+ Transmission and transmission
+ Suspension bracket and steering
+ Brake system
+ Anti-blocking system of brakes
+ Wheels and tires
+ Body electrical system
+ System of ignition
+ Lighting
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ body Elements
+ Search of malfunctions
+ Specifications

List of malfunctions


Malfunction sign
A. The indicator of temperature rises slowly, working temperature is reached later, insufficient heating effect The plate of the valve of the thermostat is blocked in the provision "openly" ("offen"), for example because of deposits; the stream to a radiator remains constantly open. The engine too long remains in the mode of operation of cold start. Within a short period of time there should be, however, no damages. Despite it, the thermostat should be replaced as soon as possible.
B. The arrow of the indicator of temperature completely deviated to the right, despite the correct level of liquid, the indicator of cooling liquid blinks. The radiator and the lower tube to a radiator remain cold. The plate of the valve of the thermostat is blocked in situation "Is closed" ("zu") (for example because of a faulty or not tight sleeve of the thermostat). It is not necessary to continue the movement by no means, otherwise the engine can sustain the most serious damage because of an overheat! Immediately to replace the thermostat. 

 Help: if the engine begins to boil on the road because of the faulty thermostat, either the wrecker, or removal of the thermostat on a place can help. If you decided to remove the thermostat, it is necessary to wait until temperature of the cooling means does not go down. At this time you can get capacities for plum of cooling liquid.

Removal of the thermostat

At the 6-cylinder engine the case of the thermostat (shooter) is located to the right of the block of cylinders.

Removal of the jammed thermostat on the way – quite problematic occupation. It is located quite deeply below so it is necessary to merge almost all okhladayushchy liquid. Besides at the hot engine it is necessary to wait long before it is possible to start working, without being afraid to scald themselves hands. At installation of the new thermostat it is necessary to replace also sealing laying on the case of the thermostat or the water pump.


  1. Completely to merge cooling liquid.
  2. Models with 4-cylinder engines: to remove the lower protection of a motor compartment (the head Elementy of a body).
  3. To remove a hose below on the case of the water pump (it was already made for plum of cooling liquid).
  4. To turn off two bolts on a cover in the lower part of the case of the thermostat.
  5. To remove a cover and the thermostat.
  6. Models with 5-cylinder engines: to turn off two bolts on a thermostat case cover.
  7. To press on a cover aside and to remove the thermostat.
  8. Models with 6-cylinder engines: to take off maple a belt, to take out the tension device (Generator).
  9. To remove the protection cover of a gear belt (head Dvigateli). The gear belt remains established.
  10. To remove the cooling system hose conducting to a radiator and located below on a thermostat case branch pipe.
  11. To turn off two bolts on a thermostat case cover.
  12. Carefully to lift a gear belt through a partition on the thermostat case, to remove the thermostat case.
  13. To take out the thermostat.
  14. All models: at installation of the new thermostat its smaller condensing plate has to show towards the engine.
  15. Only models with the 6-cylinder engine: the air valve on an external ring of the thermostat has to show up.
  16. To replace laying.
  17. To tighten bolts on the case of the thermostat or the water pump the moment of 10 N • m.

Check of the thermostat

With the thermometer for jam making you can define, whether the regulator of cooling liquid opens at the ordered temperature.

 Beginning of opening
Completion of opening
Rise height
about 87 °C
about 102 °C
7 — 8 mm


  1. To remove the thermostat.
  2. To hang up the thermostat in a pan with water and to warm up water.
  3. To check, whether the plate of the valve rises at 87 °C from a saddle.
  4. Completion of opening at this experience cannot completely be reached (in an open pan water boils, as we know, at 100 °C), but it is at least possible to see, whether the thermostat opens further.
  5. Full height of rise by that is almost reached. That it is possible to see, it is enough to draw a conclusion on serviceability or malfunction of the thermostat.