Compression Check: Testing and Inspection

Compression, Checking

• The compression can also be checked using a vehicle diagnostic tester such as the vehicle diagnosis, testing and information system (VAS 5051 B).

Special tools, testers and auxiliary items required

• Adapter (V.A.G 1381/12)

• Compression Tester (V.A.G 1763)

Test Conditions

• Engine oil temperature must be at least 30 °C (86 °F).

• The battery voltage must be at least 12.7 volts.

• All electrical consumers such as, for example, lights and rear window heater, must be turned off.

Test Sequence

- Remove the glow plugs from the corresponding cylinder. Refer to => [ Glow Plugs ] Description and Operation.

- Install the adapter (V.A.G 1381/12) in place of the glow plugs.

- Check the compression pressure using compression tester (V.A.G 1763).

• Using the tester, refer to the testers operating instructions.

- Operate the starter until the tester show there is no further increase in pressure.

Compression Pressure:

• New: 25.0 to 31.0 bar

• Wear limit: 19.0 bar

• Permissible difference between all cylinders: maximum 5.0 bar

- Install the glow plugs to the corresponding cylinder. Refer to => [ Glow Plugs ] Description and Operation.

• By disconnecting the connectors, Diagnostic Trouble Codes (DTCs) are stored to memory. After the test, check the fault memory and erase, if necessary.

- Read the Engine Control Module (ECM) DTC memory and erase all DTC entries. Refer to "Guided Functions" in the vehicle diagnostic tester.