Compression Test

GENERAL INFORMATION

The compression test allows you to assess the condition of the engine. Specifically, the test shows whether the valves and pistons (piston rings) are in good condition or worn. In addition, the test results indicate whether the engine should be replaced or overhauled. A compression tester is required for this test.

The pressure difference between individual engine cylinders must not exceed 5.0 bar. If one or more cylinders have a pressure difference greater than 5.0 bar, this indicates a valve malfunction or wear of the piston rings or cylinder bores. If the wear limit is reached, the engine must be overhauled or replaced.

When performing the compression test, the engine oil temperature must be at least +30 °C. The engine should be warm to the touch; if necessary, warm up the engine. The engine temperature must not be too high, otherwise the threads in the cylinder head may be damaged when unscrewing the spark plugs.

PROCEDURE

1. Switch off the ignition.

2. Remove the injectors.

3. Disconnect the fuel cut-off valve connector.

Warning: If the connector is not disconnected, fuel will flow out while the engine is cranked.

4. Check the compression pressure.

5. Install the injectors.

6. Connect the connector to the CO reduction valve.

Engine/Engine speed during test/Compression pressure in bar New Wear limit 2 L Diesel 200 30 – 33 25