Knock in front suspension...grrr...

[RobbieSadr]

My car is an E240 54 registration.
The front ball-joints have been replaced recently but a knocking noise at slow speeds over bumps remains.
The car has been on a ramp and the garage looked at every part of the suspension, suspecting the anti-roll bar but no signs of anything out of place.
They offered to strip the front suspension but with no idea where the noise is coming from.
Needless to say I said no thanks at that point...
Has anyone any ideas what it could be? Any suggestions would be appreciated.
Cheers...

 

[Wighty]

Anything loose in the boot by the spare buddy ?

 

[onefortheroad]

Arb link arms or strut top mount bearings.

 

[RobbieSadr]

Anything loose in the boot by the spare buddy ?

Nothing loose in the boot or car, plus the noise is definitely coming from the front and comes at slow speed over rough roads.
Thanks for the suggestion...
Cheers

 

[RobbieSadr]

Arb link arms or strut top mount bearings.

All been checked and nothing adrift...
Thanks for the suggestion...
Cheers

 

[Yugguy]

The W204 with standard suspension has an issue with low speed knocking, it's internal to the shocks, can't be visibly seen. I had it. Perhaps this is something similar? Only problem is it takes changing the shocks to fix it.



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.

 

[RobbieSadr]

Shall investigate...cheers

 

[RobbieSadr]

Have spoken to experienced Merc fitter and he confirmed that the noises come from the shock absorber/struts.
So gonna need a couple quickly, any thoughts on potential suppliers?
Dread to think what main dealer will charge...
Cheers

 

[Yugguy]

Hopefully you can get aftermarket, I replaced mine with Sachs that have been fine. My Indy sourced them at a decent price.

 

[RobbieSadr]

I'll pass the information on, thanks for the tip Yugguy!
Cheers

 

[onefortheroad]

All been checked and nothing adrift...
Thanks for the suggestion...
Cheers

what precedure was used to check the top mount bearings

All been checked and nothing adrift...
Thanks for the suggestion...
Cheers

can you explain the technique used to check the strut top mounts , as i have a similar rattle at below 10 mph over small bumps.

 

[RobbieSadr]

The car was put on a ramp, raised to head height and then a jacking assembly was placed across the ramp and under sills each side. The car was then raised so the suspension wasn't under normal load. This freed the suspension and by using a heavy lever under the wheels, which were just above the ramp, the wheels were raised slightly and all joints were examined closely.
No unusual movement was apparent in the lower area of the suspension or anti-roll bar. (hope this helps "onefortheroad"?)
A friend suggested an ex Merc mechanic who told me the symptoms were as he had seen many times and the root cause was invariably the shocks.
When coupled with the comments from Yugguy, above, even though his were on a W204, the root cause remains valid.
Will get the car sorted and Sachs seems to be the place to go...
The noise only developed at slow speed and over undulations on the road surface - and boy we have cornered the market here in Cambs for rough roads!!
Thanks to all who made contact and gave some valuable advice, it's greatly appreciated...
RobbieSadr

 

[LostKiwi]

boy we have cornered the market here in Cambs for rough roads!!

I think you've probably just ended up with the overflow from Sheffield. Not been anywhere where the roads are so appallingly bad.

 

[onefortheroad]

The car was put on a ramp, raised to head height and then a jacking assembly was placed across the ramp and under sills each side. The car was then raised so the suspension wasn't under normal load. This freed the suspension and by using a heavy lever under the wheels, which were just above the ramp, the wheels were raised slightly and all joints were examined closely.
No unusual movement was apparent in the lower area of the suspension or anti-roll bar. (hope this helps "onefortheroad"?)
A friend suggested an ex Merc mechanic who told me the symptoms were as he had seen many times and the root cause was invariably the shocks.
When coupled with the comments from Yugguy, above, even though his were on a W204, the root cause remains valid.
Will get the car sorted and Sachs seems to be the place to go...
The noise only developed at slow speed and over undulations on the road surface - and boy we have cornered the market here in Cambs for rough roads!!
Thanks to all who made contact and gave some valuable advice, it's greatly appreciated...
RobbieSadr

i get all that , but i still fail to see how they diagnosed the strut top mount bearings. you may find if you change the shocks the noise remains , so id recommend spending a little extra on 2 new top mounts also , i think im going to have to dig deep into my pockets and replace both my front shocks and top mounts , ive replaced all of the lower arms and hub ball joints at cost , but this annoying rattle remains. hope you get sorted and thanks for the review.

 

[Yugguy]

If you're changing shocks, then yes, change top mounts as well, as it wont be any more labour if you do it at the same time.

 

[RobbieSadr]

Thanks again guys, I shall ensure top mounts are sorted out one way or another too...
Cheers
RobbieSadr

 

[gizze]

My money in on top mounts too.

I have yet to have a car where shocks have made a noise like that, sure they get sloppy, but no clunking.

In order it is usually...

Anti roll bar bushes
Drop links
Front control arms
Top mount bearings

I wonder if everyone says 'Ohhh, it was the shocks" because they always do the top mounts at the same time, silly to do them.

 

[RobbieSadr]

Have had all the parts replaced and now noiseless, apart from the rubbish road surface noises...
Thanks to everyone that responded, all most useful.
Cheers

 

[onefortheroad]

Have had all the parts replaced and now noiseless, apart from the rubbish road surface noises...
Thanks to everyone that responded, all most useful.
Cheers

what did they change ?