squeaking noise from the engine
 

it emits this sound when the engine is not warm enought or during the first acceleration in the morning ;after that the engine becomes normal

Possible time for belts replacement and at the same time inspect puleys too, should solve your issue!

Agree...pulley dampeners, pulleys, belt(s);
though, I've had all changed and I still get
that near ubiquitous BMW squeal on very
cold days, at start up/drive off.

Maybe Weasel or killcrap can add an opin...
GL, mD

+2 for a loose belt. probably the alternator belt

Idle tensionor Pulley...After a few more months, the sound will stay there and be audible even when the car is warm...