Some likely problems might be (1) an overcharge, causing too high a load on the compressor, or (2) a blocked expansion valve, causing very high pressure and corresponding overload on the compressor. Question: Did the repair tech flush the system and replace the drier? If the old compressor was in the process of failing and/or failed, those things need to have been done to assure a successful repair. Otherwise, the expansion valve would surely get plugged up with contaminants from the old compressor. So, you should make sure that the system was properly serviced! A new compressor should make no noise when properly replaced. Compressors do make an intermittent load on the drive belt, which can cause a loose belt to vibrate, so the belt tensioner is a distinct possibility, as the motor mounts would be if the vibration occurs at idle.

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Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C