Audi A4, S4

since 2000 release

Repair and operation of the car


Audi A4, S4
+ Introduction
+ Governing bodies and methods of safe operation
+ Current leaving and service
- Engine
   Specifications
   Removal and installation of the top cover of the engine / lower protection of a motive compartment / stretcher
   Check of a compression in engine cylinders, identification of leaks
   Check of the engine by means of the vacuum gage
   + 4-cylinder petrol engines
   + 6-and 8-cylinder petrol engines
   + 4-cylinder diesel engines
   + 6-cylinder diesel engines
   + engine Lubrication system
+ Cooling systems, heating and air conditioner
+ Power supply systems, release and decrease in toxicity of the fulfilled gases
+ Systems of electric equipment of the engine
+ Manual box of gear shifting
+ Automatic transmission
+ Coupling, power shafts and differential
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment





Check of a compression in engine cylinders, identification of leaks

Check of a compression

The compression gives an idea of a condition of the engine. Results of check show, whether as it should be valves and pistons (piston rings), or they are worn-out. Whether Besides, results of check allow to make the decision to replace the engine, whether the complete repair is required to it or to replace sealing laying of a head of cylinders enough. For check it is required kompressometr which for petrol engines is offered in specialized shops for reasonable price.

For diesel engines it is necessary kompressometr with a limit of measurements approximately to 40 atm.

The engine has to be heated-up up to the working temperature, the battery — is completely charged. You will also need the help of the assistant.

The most admissible difference of pressure in separate cylinders can make 3.0 atm. (for diesel engines of 5.0 atm.).

Compression pressure grows in the serviceable engine very quickly. The low value shown after the first cycle, increasing with the subsequent cycles indicates wear of piston rings. The low value after the first cycle which is not increasing after the following signals about that, something valves are not tight, or laying of a head of the block is punched (also the crack in a head can be the cause). Can lead existence of a deposit on plates to decrease in a compression of valves.

It must be kept in mind that because of the different speed of rotation of a starter on different models the results received as a result of measurements can differ. The results received at measurement of a compression have to be approximately identical to all cylinders.

If pressure is in any cylinder at the level of minimum admissible and even below, for clarification of the reason execute to a trace yushchy actions. Pour in the cylinder through an opening for a candle in a teaspoon of motive oil and repeat measurement of a compression.

If oil addition temporarily improved a compression, most likely, wear of the piston, rings or the cylinder is the reason of its decrease. If the increase in a compression did not occur, it is possible to assume that the reason — in leakage of valves or the punched laying of a head of the block.

Low compression in two next cylinders almost for certain — a consequence of breakdown of laying of a head. Availability of cooling liquid in combustion chambers or in a case of the engine will confirm this assumption.

If the compression in one of cylinders is about 20% lower, than in the others, besides turns of idling are unstable, the reason, perhaps, excessive wear of a cam of a cam-shaft.

After completion of check establish to the place of a spark plug (address to the Head the Current leaving and service, put on them tips of high-voltage wires, attach the socket to the ignition coil. Establish into place a plastic cover of the engine and a safety lock of the fuel pump.

Values of pressure of a compression for various engines are given in Specifications.

Petrol engine

 PERFORMANCE ORDER

  1. Switch off ignition.
  2. Engine of 1.6 l: Disunite the socket of an output step of the coil of ignition. The output step is in one case with ignition coils on the engine.
  3. Take out a safety lock No. 28 of the fuel pump.
  4. Engine of 1.8 l: Disunite sockets of coils of ignition and injectors.
  5. L engines 2.0, 2.4 and 3.0: Remove ignition coils. Disunite the socket of injectors.
  6. Remove all spark plugs, address to the Section Check and replacement of spark plugs. Check of a condition of high-voltage wires.

At a provorachivaniye of the engine do not incline over the engine. There is a danger of traumatizing owing to emission of particles of soot.

  1. Turn the engine a starter to remove a deposit and soot.

Establish a check point in neutral situation and tighten the parking brake.

  1. Screw kompressiometr according to the guide of the manufacturer in an opening for a candle.
  2. Ask the assistant to press a pedal of gas and during check to hold it a foot.
  3. Turn the engine approximately on 8 turns so that on a kompressiometra there were no pressure throws any more.
  4. Consistently check all cylinders and compare the received values of pressure to the set.
  5. Establish to the place of a spark plug and fix them the moment 30nm, address to the Section Check and replacement of spark plugs. Check of a condition of high-voltage wires.
  6. Again join all disunited sockets, if necessary, insert into place a safety lock.

At a rassoyedineniye of sockets in the control unit of the engine data on malfunctions register. It is recommended to remove as soon as possible the written-down data on HUNDRED AUDIS.

Diesel engines

 PERFORMANCE ORDER

  1. Engine of 1.9 l: Disunite the central plug of the engine. For this purpose turn the screw with a notch to the left. Disunite the socket of spark plugs.
  2. Engine of 2.5 l: Disunite the TNVD socket.
  3. Remove all glow plugs, address to the Section Removal and installation of candles of an incandescence.
  4. Screw kompressiometr with flexible accession instead of incandescence candles.

The values of a compression specified in Specifications correspond to measurement by means of a kompressometr of V.A.G. In case of use of other measuring devices deviations are possible. In this case it will only be possible to measure dispersion of pressure on separate cylinders.

  1. Turn the engine approximately on 8 turns so that on a kompressiometra there were no pressure throws any more.
  2. Establish to the place of a glow plug and fix them the moment 15nm. Attach a wire.
  3. Join and fix all sockets.

At a rassoyedineniye of sockets in the control unit of the engine data on malfunctions register. It is recommended to consider and remove the written-down data as soon as possible.

Check on leaks

During this check are defined exit speed from cylinders of the compressed air pumped in them and directly a place of leaks. This check is alternative to check of a compression. Moreover, from many points of view it is much more effective as visually leaks simpler to reveal a source, than to comprehend results of measurement of a compression.

The equipment necessary of a dlyaproverka on leaks, does not belong to public therefore performance of this check should be entrusted specialists of the service center.