Common leak areas (as the car ages) are usually the rubber connectors at every vacuum intersection. I have come across many w123s and w126s (including both of mine) with this issue but not too many w124s so I wonder if they improved on it the material at all for the later chassis.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth