Rockin/shaking when revving engine?

[drevilkep]

So I've noticed my new-to-me 189,000 mile iS has a weird vibration when I'm revving the engine or accelerating.  At about 1800, 2500, and 3100 RPMs, the engine shakes slightly, but enough to rock the car a little and move the shifter.  It's more of a rocking, rather than an outright vibration (though the engine does vibrate too).  I don't think it's driveshaft related because it occurs when standing still, in neutral, as well as when accelerating.  I was thinking motor mounts, but I did the test where you set the E-brake, let the clutch out, and watch for engine movement.  The engine doesn't seem to move much or at all, so I'm not sure about the mounts.  They aren't leaking or cracked at all.  The car does seem to vibrate more than I would expect all all speeds and at idle.   Any ideas?

[bearsbmw]

mine did this and it was the tranny mounts

[Cobra Jet]

If you vehicle has 189,000 miles on it and the engine mounts are the original units, they HAVE to have some cracks or show signs or cracks...  Get under the car with a bright light and look at each motor mount and examine them thoroughly for any signs of cracking or deterioration.

I would replace both of them w/ the miles you have on the vehicle.  Also check out the tranny mounts as suggested too.

[xwill112x]

shake your motor by hand pretty hard...
if it sqweeks quite a bit then your sub frame may be cracked...

[dinu.negrean]

Is your oil thin?