Hmm.

I would look for things like missing gaskets on the air filter housing, broken "snorkel", and so forth, along with squashed engine mounts.

MB does NOT make loud engines, hasn't since the early 60's when engine/road noise were identifed as major causes of driver fatigue and distraction. "Induction" noise is likely a leak or something loose, and any MB engine mounted on gel filled mounts (basically anything after 1985 except the W126) will be MUCH louder with bad mounts. They get amazingly quiet again when the mounts are replaced.

Something else to look for is a minor exhaust leak, dead mufflers, bad tranny mount (good for excessive vibration on acceleration) and bad flex disks or center bearing carrier.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!