300SDL Clunking on Takeoff and Stopping
 

My 1987 300SDL makes a clunking noise whenever I come to a stop or get moving again. I can make it clunk while at a stop by holding the brake and tapping the accelerator and it clunks with every tap. When the vehicle is in motion there is no clunking. I replaced the engine mounts last fall and I replaced the rear axels as well (the clunk is definately not the cv's). Any ideas what may be going on?

How do the flex disc as well as the center bearing support look?

Replace flex disks, centering bushing and center bearing support if you decide the disks need servicing. One way to remember which bolts to remove is that the flex disk stays on the shaft. Mark the 2 halves of the drive shaft so you can get them back together in the correct position relative to each other.

The entire shaft was balanced as a unit and they should stay that way of course,
as s/u/ming no one has messed with them.

Most likely your strut rod bushing is gone.. It will go forward clunk & while braking. Common problems on these cars. :)

What brand motor mounts did you use?

If it clunks while powerbraking, it could be motor mounts, flex discs, the diff, or the axles.

Alternative direction (something worth checking) =>

Retaining bolts on brake callipers

Retaining springs on back of brake pads

Loose wheel bearings

:clap:

99.9% Problem

... Guide Rod? there is a bearing/bushing in the body. not terribly difficult to replace.

Here is a W126 DIY article on the repair.

PeachPartsWiki: Suspension Bearing Bracket guide rod mount replacement


Charlie