I am only familar with the E320's - not sure if this was a problem with the E430's.

To remove the harmonic balancer you will need a metric hex head "socket". I bought a set of three at an autoparts store. One size fits the rear differential plug and the largest size (don't recall the exact size) fits the harmonic balancer.

I used a 3/8" x 3" socket extension to keep the flywheel from rotating. The prefered method is to rent the proper tool (try a local rental store which rents automotive tools).

As Kestas mentions a breaker bar is essential. I tried an air impact wrench but at the time I did not have a suitable air compressor to break the bolt loose.

When replacing the harmonic balancer, put some blue locktite on the bolt to keep it from coming loose.

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Ray
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles