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The latest knocking noise ?

6K views 36 replies 18 participants last post by  Valkirk 
#1 ·
Read a lot threads about rattles and knocks but my week old car has this one - intermittent and only when going round bends or roundabouts (i.e. when the car rolls) a single loud knock or clonk that sounds like it is coming from behind - or even inside ! - the drivers seat (that on the right in the UK). Already driving me nuts - especially as I get it twice most times, once when turing left or right into a bend and twice when I straighten up. Anyone else experienced this and had it fixed ??
I owned an ML320 that rattled like a tractor fron new and every time I took it to the dealership they took it apart again and when I got it back there were bits hanging off it - and the rattle was still there. So I am obviously reluctant to take this problem to the dealer...
 
#2 ·
Do you have Air Scarf? If so it may have come loose. The blower is clipped into place and looks like it could be easily dislodged.
 
#10 ·
Guys - I am still suffering ! Took it to the local dealer the other day and the technician heard the knock straightaway - again only rolling into bends/roundabouts and then again rolling out - somewhere right side rear - I am sure it is the drivers seat.... He could not say for sure (of course) where it was coming from and needed to interrogate the corporate database to see if anyone had reported and had fixed a similar problem (interesting they have this database - obviously they get lots of problems....?). Anyway I am waiting to hear back but the dilemma is they will want it in to strip it down and they did this to my box of nails ML and it was never the same... Meanwhile the knock is driving me CRAAAAAAAAAAAZZYY ! Anyone ?
 
#11 ·
someone on the assembly line probably left a tool inside that is rolling around. look on the bright side, maybe you got an extra that we did not.

i was driven crazy by a knocking sound for about a week and then i realized that it was the flashlight i put in the center console rolling back and forth.
 
#12 ·
innherb - 5/13/2005 3:44 PM

(interesting they have this database - obviously they get lots of problems....?).
The "manufacturers" of the software I work on have issues databases that they refer to regularly, in fact one internal one and one for users not hugely different from this R171 forum. Its good practice and I would not see it as indicative of lots of problems per se.
I had a bit of knocking at one point. I keep CD/DVDs in the drop down storage in the centre console. Since I only had a couple in there they moved around, but now I make sure there are enough so that they are secure in there, so no knocking.
 
#14 ·
So - my car is booked into the service centre 6th June to investigate this knocking but I was cra**ing myself as experience with my M class and CLK is they strip the car apart to find the problem and NEVER put it back the same way again.

Anyway I had today off to enjoy the roof down with global warming 88 degrees in May in the UK and decide to visit the service centre. I told the senior technician I am sure the noise is coming from the drivers seat and after a road test he agrees with me ! He reckons it may be a 'stress fracure' of the seat !!!

At least the problem is pinned down and the solution maybe as simple as a new seat. Anyone else had problems with their seats ??
 
#15 ·
The fixes for this knocking sound seems to be 'everywhere'.

My SLK350 has been to the dealership 5 times and after they lubed the door strikers, lubed and retorqued the rear sway bar links, the knocking sound seem to have subsided.

My latest round has to deal with the wind noise coming from the left side (driver side) c-pillar window. I have the cracking sound (sounds like static from speaker but it is not) coming from the window area. So far, the dealership has realigned the window, replaced the seal, swapped out the window regulator .... sound has gone down but if there is a strong cross wind, you hear it again.

I hope this bit of info helps others with the knocking sound problem.

GL
 
#16 ·
Well the car went into the service centre today and they located the problem with the drivers seat, apparently some bushes need replacing that connect the seat to the elctronic drive mechanism. This must be a lemon build issue rather than wear and tear after 1500 miles (I am not that heavy !).

Will report again when I get the car back tomorrow to confirm its fixed the problem. Meanwhile if you are having similar problems (see the original post on this thread) you may want to point them at this fix.
 
#17 ·
Well they did not fix the problem - why am I surprised ? - because they thought they could order up these replacement bushes but MB are saying they have got to get some modified ones manufactured to fix this 'known problem'!! THe service centre cannot give me a lead time for deilvery so I just get the car back with the knocking...

I am sceptical this is the problem anyway - why ? Firstly it does not sound like its coming from the botom of the chair (the bushes are at the fixing point of the seat to the running mechanism) it sounds like its coming from the seat back. Secondly if the seat was not securely fixed surely I would feel movement - I dont. Thirdly the passenger seat does not make a noise. Fourthly, why hasn't anyone else on this forum reported this 'known problem' ?

I guess I have to give them the chance to get and fix these new bushes to see if I am wrong. Meanwhile it is spoiling my enjoyment of the car.[V]
 
#19 ·
Sounds like you may have the same problem as me. I spoke with the actual technician who diagnosed my problem and I am more confident they have correctly identified it. The bushes that need replacing are at the fixing point of the seat back to the seat base - not the base to the running mechanism as the front desk guy had told me (idiot !). He told me MB are replacing all these bushes on latest builds with a modified type - but only on the drivers seat curiously - and that is why they are out of stock.

Suggest you test this by going round a corner or roundabout fairly sharply whilst leaning forward (i.e. no contact with the seat back) and if you dont get the knock then you have the same problem - as it only happens when the seat back is under load. Then get your dealer/service centre to order you some bushes as well!

Good luck. [8)]
 
#21 ·
My SLK has the knock too. This too drives me up the wall as my old SLK 230 parcel shelf used to rattle too!
It goes in for warrenty next week with a wad of print-out from the threads.
I wonder if a pattern is emerging. All owners irrespective of whether LHD or DHD say it is on the right. I dont have air scaft. The Seat does not touch the back and seat belt buckle is secure.
I think there is more than one rattle but it seems like it is coming from behind me and so
I don't think it is the seat.
I've tried the following:
- Plastic clips rounf the door catch
- Rags stuffed in door gap

Hypothesis - I think it's possible the rattle is connected with the boot (trunk) lid. My boot lid has marked the bumper and been difficult to shut. The noises seem to be provoked by lateral movement rather than just going over a pot hole. It would be interesting to see if anyone else who has the rattle is also suffering the damage to their bumper too.
 
#22 ·
My symptoms are exactly the same. It's not the seat. The rattles are mainly heard when i am braking, occassionally over pot holes and when turning sharply. It sounds like it is coming from teh rear parcel shelf or mechanisms round it or possibly from the boot lid.
 
#24 ·
Well the modified bushes were fitted today and guess what - they did not work !!!

So I have now demanded a new seat and the techy is saying I need a new seat base and he is arguing the toss with MB Uk technical dept.

Am I REALLY the only one to have experienced this problem ?

Its a good job the car is so good to drive and look at otherwise I would be a lot more pissed than I am....[V]
 
#26 ·
Has anyone found what causes all these rattles at the back of teh car yet. Mine is booked into Mercedes this week but i just wondered if anyone had been told what causes any of these rattles
 
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