Compression

Measurement of compression allows to evaluate the technical condition (the degree of deterioration of the individual parts) of the engine, as well as the need for major repairs. To perform this operation required compressometer.

The amount of compression of gasoline engines are listed in Table. 5.1.

Table 5.1 The values of compression gasoline engines

The pressure difference in the cylinder should not exceed 1.5 bar. In older engines compression decreases, but if the difference does not exceed the permissible limits, it is not a malfunction. Once compression reaches the lower limit, should repair or replace the motor.

If the compression cylinders differs by more than 1.5 bar, the reason should be sought in the following:

- Wear of pistons and piston rings;

- Sticking piston rings;

- Deterioration of the cylinder (often due to sticking rings);

- A deposit on the valves and seats;

- Damaged valve;

- Burned valve (when the gap is too small).

Measurement of compression

1. Warm up the engine to operating temperature. After this, continue for about 5 km to ensure sufficient oil temperature.

2. Stop the engine by turning off the ignition.

3. Open the hood.

4. The parking brake to slow down the car.

5. The shift lever is set to neutral (or to "P" - a car with automatic transmission).

6. Remove the spark plug.

7. Insert compressometer 1 (Fig. 5.3) into the threaded portion of the spark plug, pressing sealing cone 2.

8. Connect the recorder:

- Unscrew the cover mounting of the control unit;

- In the case of the control unit, disconnect the connector terminals "50" and connect pin 1 of the connector to the wire control circuit recording instruments;

- Remove the cover of the positive terminal "30" on the left wheel arch in the engine compartment, and connect the power cord recorder to the positive terminal "30".

9. Ask your assistant to press on the accelerator pedal up to the stop and hold it in this position throughout the test.

10. Rotate the crankshaft starter several times by clicking on the contact switch recording instruments, to throw out of the cylinder carbon deposits and soot.

11. Press the contact switch device, turn the crankshaft of the engine starter (not less than 9 turns) until no change in the readings.

12. Record the compression setting.

13. Check consistently all cylinders and compare the results with the nominal values.

14. Replace the spark plug.

15. Connect the terminal "50" of the control unit and replace the cover.

16. Close the cover of the positive terminal of the "30" on the wheel arch.

17. Close the hood.

The differences in the sequence of activities for the V6 engine

1. Remove the air filter with mass air flow sensor.

2. Remove the left side of the ignition coil.

3. Remove the cylinder from every one spark plug.

4. After checking the compression consider a specialist garage storage device engine fault codes and, if necessary, delete its contents.