BMW X5: Workshop Hints On Cylinder Leakage Testing

When performing cylinder leakage tests, the following tips might be helpful: Remove all spark plugs to allow easier rotation of the engine. (If this test is done after a compression test, the plugs should already be out).

• Perform the leakage test on all cylinders, not just the problem cylinder. This would indicate any other problems which can be rectified. This eliminates any repeat repairs and wasted diagnostic time.
• Perform the leakage test in cylinder firing order starting with cylinder #1. It takes two revolutions of the engine to complete the leakage test. Start at cylinder #1 and rotate the engine to the next cylinder in the firing order. Divide the number of cylinders into 720, the result is the number of degrees that each cylinder fires. For example, if you divide a 6 cylinder into 720, this equals 120 degrees. If you start at cylinder 1 and rotate the engine 120 degrees in the direction of rotation, you can check the next cylinder in the firing order. This process eliminates the need to rotate the engine an excessive amount.

Fig. 4: Cylinder Leakage Testing Tips

Cylinder Arrangement And Firing Order

Front of Engine

Fig. 5: Identifying Firing Order

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