I have just purchased my first Mercedes c250 sport from a local dealer, I have had it a couple of days and can hear a bad knock on the front end , I have had to both my local garages and none of them can find anything yet both of them can here the knock any ideas ??
PobodY
MB Enthusiast
When does it knock? - When the engine is hot/cold?
If no garage can spot something obviously wrong, the chances are it's not something major that's worn or broken. - That doesn't really help you though.
If no garage can spot something obviously wrong, the chances are it's not something major that's worn or broken. - That doesn't really help you though.
I had a knock on the front NS which several garages failed to identify by the usual method of levering all the suspension joints which I'm guessing is what your garages did. I managed to find this service bulletin which for my symptoms pointed towards the strut as a possible cause and sure enough that what it turned out to be. One of the Pros here confirmed it was not an unheard of fault.
Hope this helps:
Front Strut / Shock Tower: By Symptom
Technical Service Bulletin # LI32-25_P-048381
Date: 091208
Suspension - Front Axle Dull Thumping Noise On Bumps
NOISES FROM VICINITY OF FRONT AXLE ON UNEVEN ROAD SURFACE
Topic number
LI32.25-P-048381
Design group
32.25 Shock absorbers/damper struts/spring struts
Date 12-08-2009
Validity
Model 204 without code 483 (Vehicle dynamics package), without AMG; Model 204.0## #A 185017 up to * 195993 with head bearing
Reason for change
Topic extended to FA shock absorber / torsion bar linkage. / Supersedes DTB P-B-32.25/67
Reason for block
Complaint:
Dull thumping noises or metallic rattling from vicinity of front axle on slightly uneven road surface and/or repaired road surface.
Note: Noises occur in lower speed range (20...approx. 70km/h).
Cause: Several causes are possible:
1. Head bearings on front axle suspension struts are too stiff (Shore hardness).
Note: Noises from the head bearing occur on more uneven surfaces and sound relatively dull.
This cause affects only a small, limited production batch! Pay attention to the VIN restriction for head bearings (EPC: "Bearing, suspension strut to
body") in Validity section! On vehicles outside the restriction range, the head bearing is not the cause of the noise and may therefore not be replaced.
2. Shock absorber Noises from the shock absorber are audible on slightly uneven surfaces and sound rather more metallic.
3. Torsion bar linkage Noises caused by a torsion bar linkage only occur in a very small number of cases on this model series.
Hope this helps:
Front Strut / Shock Tower: By Symptom
Technical Service Bulletin # LI32-25_P-048381
Date: 091208
Suspension - Front Axle Dull Thumping Noise On Bumps
NOISES FROM VICINITY OF FRONT AXLE ON UNEVEN ROAD SURFACE
Topic number
LI32.25-P-048381
Design group
32.25 Shock absorbers/damper struts/spring struts
Date 12-08-2009
Validity
Model 204 without code 483 (Vehicle dynamics package), without AMG; Model 204.0## #A 185017 up to * 195993 with head bearing
Reason for change
Topic extended to FA shock absorber / torsion bar linkage. / Supersedes DTB P-B-32.25/67
Reason for block
Complaint:
Dull thumping noises or metallic rattling from vicinity of front axle on slightly uneven road surface and/or repaired road surface.
Note: Noises occur in lower speed range (20...approx. 70km/h).
Cause: Several causes are possible:
1. Head bearings on front axle suspension struts are too stiff (Shore hardness).
Note: Noises from the head bearing occur on more uneven surfaces and sound relatively dull.
This cause affects only a small, limited production batch! Pay attention to the VIN restriction for head bearings (EPC: "Bearing, suspension strut to
body") in Validity section! On vehicles outside the restriction range, the head bearing is not the cause of the noise and may therefore not be replaced.
2. Shock absorber Noises from the shock absorber are audible on slightly uneven surfaces and sound rather more metallic.
3. Torsion bar linkage Noises caused by a torsion bar linkage only occur in a very small number of cases on this model series.
Auto-mobile
MB Enthusiast
Just to add to the above, 2010 w204 had the same issue.
