Motor Mounts collapsed twice--$800 to fix each time.
Air Conditioner lost coolant twice--No leaks found by dealers or independent shops.
Electric rear windows failed to roll up twice. Costs $300 to fix each time.
Trunk closer failed twice. Costs $200 to fix.
Automatic door locks fail to open remotely. Costs $400 to fix.
Seat belt tensioner on both front seats failed. Costs $400 per seat to fix.
This car is over-designed with poor quality. There are too many useless features that break down and are expensive to fix. The list above is not comprehensive--but gives the idea of what is going on.
Had some of the exact same problems, engine mounts and seat belt tensioners.
I feel your pain. I had a 1992 W140, and at 101K miles, I sold it. Never been so happy to get rid of a car. Overall quality is just poor. Interior trim coming loose, transmission acting up, long list of little things. Spent more time in the shop than on the road. Never again.
Had I realized that MB lost a class-action lawsuit over these cars, I wouldn't have bought one in the first place!