540i Engine Shudder/Vibrations

[Chris'91'525i]

If you want to see if the engine mounts are broken, try this:

1) Start the car & set the hand brake and let it warm up.
2) Open the hood
3) Find the throttle cable & push/pull it to rev the engine. Don't be shy about revving it hard.

If the engine mounts are shot, the engine will lift up on the left side at least an inch. It is not easy to tell if the mounts are shot simply by looking at them. On a LHD car, the driver side mount is buried underneath oil & power steering lines and is difficult to look at.

We would check for bad motor mounts by;
Giving the car some gas while it's in gear with your foot on the brakes. No need to Rev motor up.
The motors torque will lift the motor right off the bad mount.

[Podmore]

aaaaaactually ...... revving in Park or Neutral won't have any effect on the trans as the only thing spinning is the gearbox input shaft, no load on the gears at all (Park locks the output shaft). You need to load the drive train, so with the trans in Drive but foot firmly on the foot brake and handbrake on, give the throttle a few sharp blips - no Italian tune-up style hit-the-rev-limiter mashing of the foot to the firewall - and have your friend (who shall be standing beside, not in front, of the car) watch for excessive movement in the engine ..... sheesh, you guys!

[Morgenster]

Hmm. Is it really an inch? I think I get about an inch of movement just by revving my M50 in neutral on the manual trans. Could be the motor mounts are kinda shot but it's not that big a deal vibration-wise.

[632 Regal]

aaaaaaaaaaactually the auto transmisions can and do fry with free reving due to the spinning drum (& clutch packs) as I mentioned earlier.

aaaaaactually ...... revving in Park or Neutral won't have any effect on the trans as the only thing spinning is the gearbox input shaft, no load on the gears at all (Park locks the output shaft)