Order of execution
1. Warm up the engine to operating temperature. In this case, the battery must be fully charged.
2. Disconnect the electrical connector from the engine stop valve.
3. Disconnect the electrical connector from the flow meter on the fuel pump.
4. Unscrew all glow plugs.
5. Instead of glow plugs, screw in a compression pressure tester with a flexible adapter hose.
6. Turn the crankshaft of the engine with a starter until the pressure recorded by the measuring device stabilizes. Record your result.
7. Check the compression in the other cylinders in the same way.
8. The compression pressure in all cylinders of petrol engines must not differ by more than 5.0 bar. Note that the amount of compression should increase rapidly on a healthy 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 worn piston rings.
9. A low pressure value at the first revolution of the crankshaft, which increases slightly thereafter, indicates a valve leak, a blown cylinder head gasket, or a crack in the cylinder head. Worn valve stem ends can also result in low compression pressure.
10. If the pressure in one cylinder is low, then carry out the following tests. Pour some engine oil through the spark plug hole into the cylinder 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 gasket between the cylinders.
13. If the pressure in one cylinder is less than 20% than in the others, and the engine runs erratically at idle, this indicates a worn camshaft cam.
14. If the compression pressure is too high, this indicates that the combustion chamber is covered with a thick layer of soot.
15. Check the compression in the other cylinders in the same way.
16. Screw in the glow plugs, tightening them to a torque of 15 Nm, and connect the voltage supply rail to the spark plugs.
17. Connect all previously removed electrical connectors.
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