If you've been plagued with a severe engine vibration in the cabin, worse at idle, it could be bad motor mounts. Replacement can be made simple, about a 20 minute job & Bentleys doesn't cover it. Mounts are about $36 ea. at your favorite mailorder supplier (J.A.C. or Zygmunt's, etc.). Yes, they are liquid filled, the new ones even have "Bilstein" on the box. That explains why the left one was wet, I always thought it was a sloppy oil filter change by the previous owner. Here's a jpeg of a cutaway. Don't ask me why I do this sort of stuff, I guess just because it's there & "I gots ta know". The upper & middle cavities are oil filled, the bottom cavity is vented to atmosphere.
This is the short version, proceed at your own risk. I have not taken any precautions such as loosening the exhaust, removing radiator hoses, etc. but in my opinion, none of that is necessary.
Remove the air cleaner assembly. Remove the upper motor mount nuts with a 17 m/m socket, swivel, & about 18" of extensions, driver's side shown in this photo. Raise the front of the car & put it on jackstands. Remove the plastic undercarriage splash pan & remove the lower motor mount nuts. The engine only needs to be raised about 1.5". Some will balk at this but I've raised many engines, BMWs' included, by lifting directly on the pan with a block of wood & a floorjack & have never had any problems. Bias the load on the front edge of the pan. If you have an overhead lift, by all means use the lifting hook at the front of the engine. Don't worry about loosening the exhaust, it's suspended on flexible mounts & will raise with the engine. Also, the engine does not tilt enough to worry about removing the expansion tank. The tips of the fan blades will contact the shroud, so being plastic, merely flex them away from the shroud as it comes up. Alternatively, one could pull the pins on the shroud & pull it up slightly. Raise the engine only as much as required to get the old mounts out. Alternatively, the right side can be lifted on the a/c compressor mount, which is more stout than the pan, and by lifting only one side, less weight has to be supported.
I replaced the transmission support mounts in a previous repair, & new ones provide little improvement unless the old ones are completely blown out & contacting metal-on-metal. To replace them, support the rear of the transmission & remove the rear crossmember. Lower the transmission slightly as required, to get to the top nuts. Inspect the transmission rear output seal for leaks while there. If it's leaking, there's a good chance the yoke shaft nut is loose (another commom problem if having driveshaft vibration problems). Make a note to fix it soon! I'll add a procedure for that later on, but it's covered pretty well in Bentley's.
gale, 92 735i
Back to Automotive repair page