This is the procedure for changing the oil return valve on the 119 engines. The problem of audible noise during cold starts is documented in Tech Service Bulletin AF05-20-U-1400EG. As mentioned eariler, the oil filter return valve becomes leaky. Oil runs out of camshaft adjuster and oil filter housing causing low oil presure during startup - then you get the cold start noise.
Remove engine compartment panel.
Unplug plug connection (10) of oil pressure sensor (11).
Unbolt oil pressure sensor (11) and remove with seal (12). Tighten to: 15 Nm.
Unbolt oil pipe (8) of air-oil cooler at oil sump.
Unbolt oil lines (7) and (8) of air-to-oil cooler at oil filter (5). Tighten to: 7 Nm.
Replace seals (9).
Unbolt oil filter (5) at crankcase. Tighten to: 25 Nm.
Remove oil filter (6) upward.
Installation Note: Clean sealing surfaces.
Replace gasket (5a).
Install in reverse sequence, observing tightening specifications and the installation note.
Check oil level in engine, adjust to correct level.
Run engine, check for leaks