BMW 7_ая the E38 series from 1994 to 2002
1. Introduction
2. Governing bodies and operation receptions
3. Settings and routine maintenance of the car
4. Engine
4.1. General information and preparatory operations
4.2. Check of kompressionny pressure
4.3. Engine check by means of the vacuum gage
4.4. Petrol M60/1 and M60/2 engines
4.5. M62 engine
4.6. Diesel M57 engine
4.7. Diesel M67 engine
5. Systems of cooling of the engine, heating, ventilation and air conditioning
6. A power supply system and production of the fulfilled gases
7. Systems of electric equipment of the engine
8. Manual box of gear shifting and coupling
9. Automatic transmission
10. Kardanny and power shafts, reducer, differential and stupichny assemblies
11. Brake system
12. Suspension bracket and steering
13. Body
14. Onboard electric equipment
15. Electric equipment schemes



4.2. Check of kompressionny pressure

For check of kompressionny pressure the help of the assistant is required.


  1. Measurement of kompressionny pressure allows to make general idea about current state of such internal components of the engine, as laying of a head of cylinders, elements of the klapanny mechanism, pistons and piston rings. The analysis of results of check allows to define, whether the engine needs major regenerative maintenance, or it is enough to replace only sealing laying of a head of cylinders. Measurement is made with the help компрессометра.
  2. Warm up the engine to normal working temperature (about the 80th hail.) also muffle it.
  3. Make sure of completeness of a charge of the storage battery.
  4. On petrol models separate sockets of electroconducting of coils of ignition.
  5. On the M52 engine remove the ECM relay; on other petrol engines remove the relay or a safety lock of the fuel pump, let's to the engine work to a full izraskhodovaniye of the fuel which has remained in lines then turn out candles.
  6. On petrol engines turn out spark plugs, and on diesel – glow plugs.
  7. On diesel models depending on type of the engine execute the following actions:
    • M51: Remove the main ECM relay.
    • M57: Separate sockets of electroconducting of nozzles and open all soaking-up channels for what remove available covers, laying, etc.
    • M67: Separate the socket of electroconducting of the sensor of provision of a camshaft (CMP).
  8. Screw in a spark plug or glow plug opening an adapter nozzle компрессометра.

For measurement of a compression of diesel engines it is necessary to make sure that компрессометр has a sufficient range of measurements.

  1. Completely squeeze out a pedal of gas and, turning the engine a starter, consider and write down indications компрессометра when they are stabilized.

Time of carrying out measurement should be as it is possible more shortly.

  1. Repeat the procedures described in paragraphs 8 and 9 for remained cylinders of the engine.
  2. Compare results of measurement by requirements of Specifications.
  3. The compression 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. Low value after the first cycle, not increasing after the following, indicates existence of leaks via valves, or on the punched laying of a head of the cylinder (the crack in a head can be the reason also). To decrease in a compression can lead deposit existence on plates of valves.
  4. The results received at measurement of a compression, should be approximately identical to all cylinders. If pressure is in any cylinder at level minimum admissible and even below, for clarification of the reason pour in in the cylinder through a candle opening a teaspoon of impellent oil and repeat measurement.
  5. If oil addition temporarily improved a compression, the reason of its decrease, most likely, is wear of the piston, rings or the cylinder. If the increase in a compression did not occur, it is possible to assume that the reason – in a leakage of valves or the punched laying of a head of the block.
  6. The low compression in two next cylinders almost for certain is a consequence of breakdown of laying of a head. Availability of cooling liquid in chambers of combustion or in a case of the engine will confirm this assumption.
  7. If the compression in one of cylinders differs from the others more, to us on 1 atm, besides turns of idling are unstable, the reason, probably, excessive wear of a cam of a camshaft.
  8. After carrying out check disconnect компрессометр with a nozzle, establish acting in film components and connect electroconducting.

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4.1. General information and preparatory operations
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4.3. Engine check by means of the vacuum gage