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.
REPLACING ALL SPARK PLUGS (N42, N40, N46, N45, N52, N52K, N51)
Special tools required:
12 1 171
12 1 200.
Necessary preliminary tasks:
Switch off ignition
Remove ignition coils.
Unscrew spark plugs with special tool 12 1 171.
Installation:
Tighten down spark plugs with special tool 12 1 171a