W204 Knock From Nearside Front, Cannot Be Found!!! 2010 C350

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gibsonk

Active Member
Joined
Oct 2, 2017
Messages
167
Location
The Titanic
Car
Mercedes
Hopefully this is the last issue i need to ask advice for on my car, thank you to all in advance for all the help and advice i have had over the last few weeks.

I have had a dull knock on my nearside front for a while now, it only happens at lower speed on bad road surfaces or when you come down the other side of a speedbump and the suspension depresses. Its quite dull and not metallic in anyway and seem to happen on the downstroke.

i have had the usual issues with W204 running gear and control arms etc. but this has never been found or resolved, just about everything i can think of has been replaced to no avail.

The car drives fine, no wandering or abnormal wear issues just this persistent knock, it has been with me for around 6 months, yes my car has been lowered but this issue has been there before the work was done.

To date the following items have been replaced.


  • Both front drop links
  • Front sway bar
  • Front upper arm (both sides)
  • Front lower arm (both sides)
  • Front Bearings
  • Discs & Pads (Twice, that's another story)
  • All four tyres
  • Springs all round
  • Dampers all round
  • Damper top mounts
  • Top mount bearings
  • Can't find anything loose
Everyone who has had the car on a ramp can't find any issues, i have checked the engine mounts and i get no abnormal movement or lifting of the engine when applying torque with the brakes on.

The only thing i can now thing is it is perhaps not in the NSF and coming from somewhere else, or its down to the Subframe bushings. I know the rear frame bushings can have issues but not aware of problems on the front.

Before i drop the subframes if anyone has any ideas or suggestions on what i can check it would be greatly appreciated
 
Engine mounts?
 
Found this, posted by forum member 190 in another thread:


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
Version
1
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
Note:
Noises from the shock absorber are audible on slightly uneven surfaces and sound rather more metallic.
3. Torsion bar linkage
Note:
Noises caused by a torsion bar linkage only occur in a very small number of cases on this model series.
 
Found this, posted by forum member 190 in another thread:


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
Version
1
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
Note:
Noises from the shock absorber are audible on slightly uneven surfaces and sound rather more metallic.
3. Torsion bar linkage
Note:
Noises caused by a torsion bar linkage only occur in a very small number of cases on this model series.


Thanks for the reply and TSB, i have looked over this and everything has already been replaced on my car, other than engine mounts or Subframe (thats scary) i cannot see what else is in the equation.

I think my next steps are to replace all the bolts on the runnig gear to make sure none are worn slightly allowing for movement and then replace the engine mounts, i understand the mounts are known to be problematic. Beyond that everythign i can think of has been replaced
 
Hi guys, had the same issues but one thing I came across is that there's a difference in the suspension components for standard and sport. I had a strut changed previously and it turns out it was the standard type rather than sport. When this was changed back to sport the noise stopped. I had also changed all the suspension components to try to stop the noise.

I have also just discovered that my car c220 w204 amg sport has two standard (circular bar) drop links fitted instead of sport (alloy cross shaped rod), any ideas if this is dangerous/major issue and should be changed? I have no handling or noise issues.
 
Thanks for the reply and TSB, i have looked over this and everything has already been replaced on my car, other than engine mounts or Subframe (thats scary) i cannot see what else is in the equation.

I think my next steps are to replace all the bolts on the runnig gear to make sure none are worn slightly allowing for movement and then replace the engine mounts, i understand the mounts are known to be problematic. Beyond that everythign i can think of has been replaced

You need a chassis ear to find this. I have one if you would like us to take a look.
 

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