The newer flex disks on the 201 and 124 chassis are designed a little different from those found on earlier models. They do not have the same tendency for catastrophic failure, but they are prone to other problems like clicking noises and drive line vibrations. This is becoming a very common problem as these cars get older. Failure has proven to have more to do with age than vehicle mileage. Just recently I had a 1987 190E come into the shop with only 80,000 original miles and the front flex disk was totally shot.
Problem & Solution
Common among these chassis:
On another customers 300E he noticed some "clicking" noise in the drive train as he drove the car at slow speed. The noise would seem to come and go. Upon close inspection the front flex disk bolts had torn loose from the flex disk shock points (see picture). I decided it was best to change both disks. After an hour and a half of work we had the new flex disks on and what a difference in smoothness!
On yet another 1991 190E a high pitched clicking sound came from a loose bolt in the rear flex disk.
RECOMMENDATION: The next time you get a chance take a look at your flex disks. Signs to look for are cracks in the rubber disk or torn disks around the bolt holes. One of the first signs of problems can be the formation of rust around the bolts and washers. This is a sure sign that the bolts are working in the holes and bushing failure is not too far off. If you find one is bad replace both. If they look suspicious just replace them. They are not expensive. We have a kit that contains both flex disks and complete installation instructions.