Audi A4, S4

Since 2000 of release

Repair and car operation

Audi A4, S4
+ Introduction
+ Controls and receptions of safe operation
+ Current leaving and service
+ The engine
- Systems of cooling, heating and the air conditioner
   - Cooling system
      The general information
      Antifreeze - a protection frame from freezing
      Replacement of a cooling liquid
      Removal and thermostat installation
      Thermostat check
      Replacement of hoses of system of cooling
      Removal and radiator installation
      Removal and installation of the fan of a radiator
      Removal and installation of the pump of a cooling liquid
   + Systems of ventilation, heating and air conditioning
+ Power supply systems, release and decrease in toxicity of the fulfilled gases
+ Systems of an electric equipment of the engine
+ Manual box of a gear change
+ Automatic transmission
+ Coupling, power shafts and differential
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment

Thermostat check



  1. The thermostat at engine warming up puts into operation the big contour of cooling.

    Thus the thermostat continuously extends, from the size "and" till the size b.

    Before removing and checking working capacity of the thermostat, be convinced that problems with engine cooling have arisen not owing to insufficient quantity of a cooling liquid or a weak tension drive a belt. Be convinced of serviceability of the indicator located on a control panel.

  1. If you have noticed that the engine long gets warm to working temperature (according to indicator indications), the thermostat, probably, is jammed in open position. In this case it is necessary to replace the thermostat.
  2. On the other hand, long warming up can be a consequence of absence of the thermostat. It could make specially or inadvertently (have forgotten to establish after repair). Do not use the car without the thermostat. The control system of the engine will hold the engine in a warming up mode longer time. During this time the engine will consume большее quantity of fuel, and the fulfilled gases will contain большее quantity of harmful impurity.
  3. If the engine overheats, touch the top hose of a radiator. If it not hot, but the engine перегрет, the thermostat, probably, has jammed in the closed position. The liquid does not get to a radiator and circulates on a small circle. In this case replace the thermostat.
  4. If the top hose of a radiator hot, it means that the thermostat is opened also a liquid normally circulates on system. In this case familiarise with the recommendations resulted in section Diagnostics of malfunctions.



  1. Remove the thermostat case.
  1. Check up thermostat position through a connecting branch pipe in the case. Measure the size "and" on the thermostat.
  1. If the thermostat at a room temperature is abroach — it is faulty and is subject to replacement.
  2. For rough check of working capacity of the thermostat suspend its case on a twine piece in a vessel with water. The thermostat case should not concern vessel walls. Start to heat up a vessel.
  3. In process of heating of water the thermostat should open (it occurs directly ahead of water boiling). As the temperature of boiling of water 100С, the thermostat can not open completely (address to Specifications). Take the thermostat and allow to it to cool down. In process of cooling it should be closed completely.
  4. If the thermostat does not open at heating or is not closed at cooling, replace it.
  5. At thermostat installation keep in mind the following.
    1. Carefully clear interfaced surfaces and replace a sealing ring.
    2. Place the thermostat in a casing, it is correct сориентировав.
    3. Tighten bolts of fastening of a cover, having made demanded effort.
    4. Establish all hoses on former places then fill in cooling liquid (address to the Head Current leaving and service).
    5. Start the engine, warm up to working temperature and be convinced of absence of leaks.