Here are the circumstances:
>'09 E350 4Matic, 36K miles
>Cold, wintery, driving very slowly (5-6 mph) on a "wash board" street.
>The knocking sound sounded just like someone knocking their knuckles on a table top.
>The sound seemed to emanate from the left front suspension.

As we exited the neighborhood on to smooth local streets, the knocking sound stopped. But I think I may have heard it previously under similar conditions. This time it was very noticeable, even "the boss" could hear it.

Comments/thoughts will be appreciated.

relinuca

 

Sounds like you need to get your street paved.

Failing that what you describe suggests that your torsion bar links and or bushings or simply shocks may be worn.

 

Actually, the road was paved but was covered mostly with about 6" of ice, except the spots where some salt had been randomly thrown down; hence, the wash board effect.

FWIW, I don't believe E-class' utilize torsion bars in the front suspension system, certainly not as a primary component, nor do they have shock absorbers per se though the McPherson-type struts within the double wishbone design perform a comparable function.

Your suggestion about a defective bushing is a good one as there are several points throughout the system with such wear-able items. Thanks.

relinuca