eugene22n

I started experiencing a cracking noise while going over speed bumps about 3 weeks ago. It happens most prevalently when I go at a speed bump straight ahead and doesn't happen if I do it very slowly but does at reasonable speeds. It makes the noise on the rebound and not on the compression. If I take the bump from the left or right its much reduced or not there. I sometimes hear if it I go over a big dip on a road. The frequency of the noise is decreased when the car is raised. There is no notable effect on the ride or handling of the car. The sound is definitely coming from the front suspension and not the rear. Also it increases in frequency when there are more people in the car.

I don't really want to bother taking it in right now (since my dealer is so far) if it's not serious like when I took it in for sway bar bushings that were causing a creaking.

Anybody experienced anything like this? Car is an 07 S550.

phatisfy

I hear a clunk sound in front of the car too but not all the time.

eugene22n

Over speed bumps and dips as well? Anybody take their car to the dealer with this type of issue?

Another user emailed me indicating it may be the torsion bar, steering system mounting bolts, or inner and outer tie-rod ball joints.

emilner

I have heard a creaking sounds when you go over a speed bump quicker than usual like you describe. It really doesn't bother me as it kind of says "slow down over speed bumps"...

eugene22n

The creaking/knocking I'm talking about happens at normal speeds over speed bumps. Not to hear it I have to crawl very slowly over the bump.

Perhaps you are experiencing "trim" creaking? Or if its very minor (without any knocking) maybe its from the sway bar bushings.

I'm going to take it in for diagnosis tomorrow.

eugene22n

Did a quick drop by to an independent shop for a diagnosis with the DTB/LI's in hand. The guy said the car has no torsion bar since its not a AWD and said he'd consult with his contacts at MB as to how to proceed.

Steverino55

Hi guys. That creaking noise is due to the control arms (upper, lower or both) as well as other suspension parts. It begins w/ the creaking sounds which you all describe and in time in becomes worse. It does not mean that the car is undriveable but it does become very noisy inside as well as out and reflects very badly on the car's. Upon checking for the suspension parts be aware that the ones for 4matic equipped cars(all wheel drive) are different from the rwd ones.

knowbenz

this noise is most often from the front sway bar. mercedes has released several dtbs or li documents on this concern. the latest one
LI32.35-P-047253 has you remove the sway bar and "glue" it
to the mounts and subframe with some pretty strong adhesive.
a quick way to check is to take out the sway bar and try to
duplicate the problem. if its gone then you have found the
problem. the noise is caused by small movements of the sway
bar in its mounting location. hope this helps

mb1000

Thanks for sharing the info.

My car start to have cracking noise from front sway bar (left side) on rebound. I thought the sway bar/rubber and mount/subframe should work like a hinging and should be moving freely. I thought the mount probably rusted and should be putting oil/grease to reduce friction to eliminate noise.

After saw your post, the fix is to glue it! Given the frequency of movement and strong force, how long adhesive can bind rubber and metal mount together, or it is just a short term bandage?

My other car (Lotus) has the same noise. After I put grease that type of noise is gone.

knowbenz

as far as ive seen its not a bandage. mb originally would have you replace the sway bar but i think the final fix is to "glue" it so there is no movement. i can defiantly see your concern with this as far as short term but so far it seems to be working. you are right some designs act like a hinge when the sway bar moves. in this application it is not the case mb doesnt want any movement there. if you applied some sort of grease and sanded and cleaned the surfaces it would probably work too. i would recommend the proven method though. the bonding adhesive that is recommended is some pretty nasty stuff probably holds the space shuttle together haha i believe its called DEVCON mb part number a0059890971. hope this helps

eugene22n

the document that I was provided by a member indicates the "knocking" is coming from the torsion bar linkage, not the sway bar. I've had the bushings for the sway bar replaced before due to it making a "metallic squeak". The indicated solution for the torsion bar movement is to epoxy it to the linkage. My mechanic has confirmed the issue and I'll have it done mid week. I'll report on the results.

The other document indicated issues with one of the following:

prestress of the steering system mounting bolts too low or
excessive play between thrust piece and steering rack or
breakaway torque of inner and outer tie-rod ball joints is too high due to unfavorable tolerance/friction conditions.

I'll continue to work to get this noise resolved.

I find it disappointing that the car is developing these issues so early. Was worry free for a very long time.

knowbenz

The "torsion bar" in the document is refering to the sway bar. The sway bar bushings are not removable from the sway bar on your car. If you had the "bushings" replaced previously then they had replaced the entire sway bar as that was the repair for the previous LI document.

mb1000

Taking the car to dealer tomorrow. Will mention the dtbs or LI32.35-P-047253 to them. Let's see. Thanks

mb1000

Problem fixed . As exactly Knowbenz said before, they reproduced the noise, applied 0059890971 glue to the sway bar rubber and mount/frame under warranty. Will see how long it will stay. Thanks for the help.

eugene22n

Done @ my indp. mechanic for ~$90 total. Car is back to perfect now. No more noises from the suspension at all. Ride quality isn't affected. I'll update if this fails in the future.

NJS430

I had this same problem with my "08" for quite some time before finally getting it resolved a few months ago. I had the dealer follow the procedure in the Service Bulletin. I believe they applied the glue to the sway bar mounts and reinstalled it.

The noise is completely gone.

eugene22n

Disappointing to hear that Mercedes let this issue drag into later years. My mechanic was complaining that the sway bar bushings are different from other Mercedes models. Something about them being incased in molded hard plastic.

mymbz

Hello everyone,
My car start to develop this problem, dealer confirm the problem and need "glue" fix but charging $490 for it , do you thing I can DIY with this problem? Thanks

eugene22n

If I recall correctly my indie did it for around $100 back in the day. No problems.

NJS430

You should pull a copy of the Service Bulletin and judge for yourself. You probably can do it yourself but it is not an easy job - especially if you don't have a lift. My dealer did it under warranty. You might want to call another dealer and see what they would charge or ask the regional MB rep to consider covering the repair since it is something that should never have happened in the first place. There is a service bulletin on it which documents that it is a known issue with the car.

mymbz

Thank you all for respond to my question, unfortunately the local shop don't know what I'm talking about, the dealer here really strick. Last time the fuse of the command display burn and I could not find the fuse chart, I told them that I need fuse replace. They told me to make apt and $145/hr for diagnostic then if confirm because of the fuse then I'll be charge for part and labor. Lucky I found info on this forum and replace it myself.
Could you please give me the link for the Service Bulletin about this. I google it but could not find
Thank you!

new550

Does someone have a copy of the service bulletin on this issue?

NJS430

I have the service bulletin but it is 2.1MB so it will not upload. It has some good High-res photos showing the procedure. It really isn't that hard to do so I think you will be good once you have it. Send me your email address and I will email you the bulletin.

phatisfy

Can you send me the bulletin to my email. Phatisfy@yahoo.com

NJS430

Just did!