Steering rack clunk at input shaft
 

This is on my 2008 E350 4Matic (123k miles now)

I have a weird suspension/steering clunk that occurs when I drive the car up a curb, and it does it worse when the car is turning at the same time.
I've replaced all control arms, upper and lower ball joints and its still doing it.

I got under the car today and had a helper move the steering wheel back and forth, and I found a clunk at the input shaft to the steering rack.
I have no idea whether this is the same problem, but at least I can start here...

Any ideas what this noise is? Is this wear in the actual rack, or what else could it be?
Here is a video:
https://www.youtube.com/watch?v=uN44-G4g5Tc

Are you able to read the codes off the DTC? It'll give you a great place to start troubleshooting. If the steering rack needs to be replaced, take a look at the link below for our guide on a DIY fix.

Mercedes-Benz W211 Steering Rack Replacement (2003-2009) E320, E500, E55 | Pelican Parts DIY Maintenance Article


-Dmitry

seems like intermediate shaft stiction noise, on japanese and usual american cars I remove the ISS and grease it with very thin teflon grease. Usually available at toyota, mazda/ford and chevy dealers.

I got back under tonight and I am suspect about the rack bushings. I think they are covered by a metal panel so I can't see them, but I confirmed its not coming from the coupler or steering shaft. Its definitely from the rack itself. So its either got to be the rack, or the rack bushings...

I removed the rack bushings tonight and the noise is still present with it no longer connected to the car, so the clunk is within the rack...I'm guessing that replacement of the rack is my only option?

Has anyone solved this problem on the w211? Having these exact symptoms on my 2005 E320 CDI. I have replaced most of the front suspension, done wheel bearings, tested bushings and ball joints ...it seems like the only thing left, and source of the noise is the steering rack. Have started to feel the clunk in the steering wheel even going down mostly even roads.

On multiple sites there seem to be posts with these symptoms and noises tracked down to the rack, but I have yet to find where someone has fully solved it!

Spending $600 plus for a rack seems like a gamble....

Replaced the driver's side inner and outer tie rod as a last ditch hope. No change, though the inner joint did feel a little loose.

Getting close to taking it to an actual mechanic, though putting in a used steering rack may be about the same price as a diagnosis.