GT-ER

I've posted on this before but after some experimenting I feel the need for more ideas on the matter.

I've read anything from "it's normal" and "it's the rear shocks" to "the fuel tank is loose".

I honestly cannot see how a noise so horrible could be "normal", especially since it's at a near crawl ( 2-3mph ). It's a very loud "clunk" in the rear when going over speed bumps but it rarely does it anywhere else. I got inside the trunk while me wife drove the car and the noise was very solid and came from both sides of the trunk walls and the floor ( it's not isolated to just one side ).

I've checked the subframe, everything is tight.

I've checked the fuel tank, it's pretty tight.

I've cleared out the trunk, nothing is loose.

I've checked for somewhat loose suspension parts with a pry-bar, nothing seems loose.

I removed the rear shocks because they have some staining from the oil that seems to be leaking out of them, but when removed they operate very smoothly and are still very strong. They will also decompress back to their extended state by themselves which means they still have a decent amount of pressure still ( like new shocks do ). They also make no noise as I compress and decompress them.

My only guesses could be that either the airmatic springs/bellows are bad ( yet they never deflate or even show signs of any problems ) or that the shocks will only clunk when decompressed at a rather quick rate ( quicker than my arms can do it anyways ).

Is there any way to check without spending $800+ on shocks only to find they may not be the problem? I'm seriously thinking about going with coilovers but fear the ride comfort will go to the trash ( the one thing I love about airmatic...being low and not loosing comfort in the process ).

BTW- I'm lowered on washers but the noise was there before the washers so they are unrelated.

john89011

I am experiencing the exact same issue with my C32, I think it's the springs.

AMGPilot

Check the Diff mounts and the axles. Also check the exhaust alignment

t-bone

Search the forums for "dead body in trunk"

It will bring up a lot of threads that have this issue. I didn't read through them all so I'm not sure what the exact cause was.

Good luck!

GT-ER

The diff is solid. Never checked the axles and I can't really see how they can make such a noise. I wiggled the exhaust as hard as possible with no noises.
I've read that, which apparently state that it is normal. I believe putting the suspension in sport 2 would make the noise go away while mine doesn't. But I simply find it impossible for it to be normal....the noise is HUGE. Everyone that gets in my car gets startled by it when I go over a speedbump.

Completely different suspension setups. My car is airmatic.

GT-ER

I feel like raising the car on my jack and letting it fall to see if I can maybe pinpoint the noise.

shardul

iTrader: (1)

I am also having the same issue. I have checked the under carriage extensively but can't resolve the issue.

GT-ER

I guess I'm going to be forced to buy the rear shocks to see if the noise goes away, if it doesn't I'm going to kick myself...lol.

stevebez

I have the same "noise" but figured its my rear reservoir that not bolted down...

Perhaps baffling in fuel tank poor / toast?

shardul

iTrader: (1)

I have you checked the upper shock mounts and all the other bushings. I spoke to a MB parts guys a while ago about this issue and he very rarely sells rear shocks.

GT-ER

When I removed the shocks I checked them out, they were like new.

chawkins2001

Did you check for the dead body??

shardul

iTrader: (1)

yes i read the dead body thread a couple of times, but seems like there is no specfic solution.

GT-ER

Has anyone disassembled the rear air bellows themselves? I can see that the bellows are bolted down from the bottom which makes me think it's because they decompress at a slower rate than the cars body does and bolting them to the suspension would make them decompress at the same rate. This also should mean that there is something holding it up on top to the body of the vehicle...except that I can't see what ( if anything ). Is there some kind of clip on system that holds the bellow to the body?

shardul

iTrader: (1)

judging from this picture is seems nothing is connected to the top but I am sure there has to be some sort of lachting assembly. it not maybe a rubber pad which could be worn out?

http://www.flickr.com/photos/13792514@N06/2129157255

ArmoE55

Everyone will probably hate this comment, but, take it to the dealer and see what they say/find?

I'm sure a reputable MB dealership would be able to diagnosis the culprit.

GT-ER

Dealer will only swap random parts until the noise goes away at my cost ( a very high one )...not an option.

shardul

iTrader: (1)

yeah i pmed a couple of people who have replaced the rear struts wiating to hear back form them on how they are attached to the top.

stevebez

I think its the airbags on rear suspension pulling away from the body as the bag cannot "inflate" enough of fast enough to catch the rebound. Its also more pronounced when the car has sat in cold temps (making the rubber more rigid).

Tested this the whole week in and out of my local parking lot... it cannot be anything else.

Not much we can do I guess - except swapping the airbag setup for coilovers.....If only in the rear.

GT-ER

That's exactly what I was thinking.

Yesterday I had a bad electrical problem in my car where my car was barely drivable ( turn out to be the intercooler pump fuse ) and interestingly enough...guess what? The noise was GONE! Not 100% gone but 90% gone. I got the same speed bumps I always get and the car barely clunked at all ( almost unnoticeable ). Fixed the electrical problem and the noise came back full force.

O-55

besides the air bags, i would check the mounts the thrust arms connect to. they're in each wheel carrier. i believe they're hydo mounts and can/will leak.

i have a bad leak on my passenger side shock and get a good thud when i hit slight bumps/dips in roads. mind you i am keeping up with traffic when my noises occur. i dont get any thuds/clanks going over speed bumps or uneven pavement at low speeds.

i'll be replacing both shocks due to the leak, but i would save your cash as they're probably not the source of your issue.

Jakpro1

I can't go over speed bumps faster than 1mph with my long tubes, but I had the exact same problem with my E500 and I think with this car before I started modding.

Something to do with the air suspension but I don't think it's a bad part etc, might be just nature of the airmatic beast.

Just a thought.

e55amg00

Are your cars equipped with spare tires? I found mine to be loose which caused the same noise. Just a thought..

tbal

I get the exact same sound going over a speed bump fast, but if I go over it slowly/smoothly I dont hear that sound. Also I noticed I only hear that sound when in S2, have yet to hear it in comfort.

GT-ER

I get the noise no matter what setting I'm in.

I honestly cannot imagine that these cars do these noises brand new, it's just absurd on a $100K car ( here in PR they went for $110K for the base E55 all the way to 120+K for the fully loaded one ). Has any of you guys had this noise since day 1 on a brand new car?

Maybe the valves inside the bellows just wear out prematurely and start to clunk.