Originally posted by rjnonnie
The harmonic balancer is the crankshaft pulley. It consists of an inter metal pulley, an outer metal ring with a rubber dampning ring between the two. This is to reduce vibrations as you concluded.
The eariler models with the V-6 engine (1998 and 1999?) were equipped with factory defective rubber dampning rings. The rubber ring would split causing the harmonic balancer to seperate. Since the failure occured after the factory warrantee expired the expense was the owner's. Mercedes has since modified the harmonic balancer to prevent premature failures.
The only way to prevent it from failing is to replace it before it fails.
If you contact your local Mercedes dealer with your model and vin #, they may be able to tell you if your harmonic balancer is equipped with the modified harmonic balancer.
OK, I called a few dealerships because I got suspicious answers and it turns out that nearly every dealership gave me different information. Here's what I finally concluded is closest to the truth:
Originally on the W210 engine you got one of two part numbers for the harmonic balancer:
112 035 0000 or 112 035 0500
Then, both of those had replacements later on in the years:
112 035 0000 was replaced by 112 035 0600
112 035 0500 was replaced by 112 035 0900
Then, finally, both of the replacements were replaced by the current part:
112 035 0800
Can anyone verify this as correct?
Also, when I asked how likely failure was I got answers ranging from "None of the harmonic balancers are defective, they just changed the part numbers" to one dealership saying "Yes, you should replace it RIGHT now, this is very dangerous".
Again, can anyone add some sanity to this madness?