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      11-02-2012, 12:41 AM   #17
Lieutenant Colonel

Drives: 2009 Crimson 328i
Join Date: Oct 2012
Location: Los Angeles

iTrader: (0)

You'd get it most at idle and less and less with high RPM.

Short answer: rumble from an engine mount problem is inversely proportional to RPM.

Long answer: the rumble is your engine shaking back and forth as the balance of the cam shaft goes back and forth. The faster the cam is moving, the less time the engine has to move up and down or back and forth on a mount, the less vibration you feel.