I do have the same noise on my E320 Wagon. I was going crazy trying to locate it. It got a lot worst after hitting a pothole. I don't agree with the idea of a ball joint failure because there is no play on the wheel. I just check it few days ago.

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New Addition to the family
2013 Passat TDI 5Miles
2004 E500 4MATIC Wagon 95k
1996 E300 Diesel 173k Sold
1993 300E 2.8 230k Sold
1994 E320 White Wagon 373K Sold
Still dreaming about ....500E


Radu Negru