All vacuum assist functions other than door locks utilize engine vacuum in the gas MBs. The diesels develop little engine vacuum, so a separate pump supplies vacuum for brakes, climate control, etc. Both types have a separate pump just for door locks.

In the gas models, vacuum leaks occur most often in the idle air hoses and interconnects. These are the larger diameter hoses between the intake manifold port, pcv orifice, airflow meter plenum, and idle control valve.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7