Checking the compression in the engine cylinders (VW Golf 4)

The engine condition can be checked by measuring the compression pressure in the engine cylinders. If this check is carried out regularly, it is possible to know in advance the beginning of engine wear, without waiting for the moment when engine wear manifests itself in low engine efficiency.

Execution order

1. Warm up the engine to operating temperature. The battery must be fully charged.

2. Disconnect the electrical connector from the engine shut-off valve.

3. Disconnect the electrical connector from the flow meter on the fuel pump.

4. Remove all glow plugs.



5. Instead of glow plugs, screw in a compression tester with a flexible adapter hose.

6. Turn the engine crankshaft with the starter until the pressure recorded by the measuring device stabilizes. Record the result obtained.

7. Check the compression in the remaining cylinders in the same way.

8. The compression pressure in all cylinders of petrol engines should not differ by more than 5.0 bar. Note that the compression value should increase rapidly on a serviceable engine. Low compression pressure on the first revolution of the crankshaft, followed by a gradual increase in pressure on subsequent revolutions of the crankshaft, indicates wear of the piston rings.



9. A low pressure reading on the first revolution of the crankshaft, which increases slightly thereafter, indicates a loose valve fit, a broken cylinder head gasket, or a crack in the cylinder head. Worn valve stem ends can also cause low compression pressure.

10. If the pressure in one cylinder is low, then perform the following tests. Pour some engine oil into the cylinder through the spark plug hole and check the compression pressure.

11. If pouring oil into the cylinder increases the compression pressure, this indicates that the cylinder or piston rings are worn.

12. Low pressure in two adjacent cylinders indicates a burnt-out gasket between the cylinders.

13. If the pressure in one cylinder is 20% less than the others and the engine idles rough, this indicates a worn camshaft lobe.

14. If the compression pressure is too high, this indicates that the combustion chamber is covered with a thick layer of carbon deposits.

15. Check the compression in the remaining cylinders in the same way.

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16. Screw in the glow plugs, tightening them to a torque of 15 Nm, and connect the voltage supply bus to the plugs.

17. Reconnect all previously removed electrical connectors.