Very clear procedure,

If I'm not wrong, all W124 diesel engines have the start of delivery ~24 BTDC ?? and the degree the locking tool engages is just a constructor choice.

Anyway, I checked my timing yesterday it was 2 degrees of.
After adjusting to the good value, the engine still smocking slightly. and the phenomenon that disturb me is the following,

When the engine is cold, it runs very wery smooth, When engine reaches operating temperature, it makes a "Tfff Tfff Tfff Tfff" noise like I have a leak in the intake air circuit.

I've checked the Exhaust & intake circuits, prechambers... no air leak, do you have any idea?