W205 C63 - Knocking / vibration over bumps at rear

[BenF]

One for the W205 owners - any of you had any rattles from the rear like the below?

From the clip, you can hear the rattle most clearly between 2-6s then 8-12s 16 and 22s as I drive down a local road. There's a little noise from the mobile phone holder but what you can mostly hear is the noise.

Video including vibration noise

Car has been to Mercedes ( had two new rear shocks, one was blown and could be knocking but wasn't it ) and a local Indy and they tried tightening up the boot lid fit (Indy) and some panels below the rear seats ( Merc ) but that hasn't cured it. I did take the plastic covers off the lower suspension arms too but that didn't help either.

I've had it up on jacks and had a good look around but didn't see anything obvious. Sounds to me a bit like plastic/metal especially as it 'vibrates' going over bumps. Apparently drop links etc all under the car are are OK, have removed everything from the boot etc. Are there any common known areas to check?

 

[JakeCs]

does it get worse going on bad roads sloping down?

 

[BenF]

Not noticeably - about the same. At higher speeds less noticeable, maybe as there's a bit more road/wind noise?

 

[f17ant]

Can barely hear it? Lower ball joints maybe?

 

[Jobsworth]

Are you sure it’s suspension? The pano roofs are notorious for rattles. Is it still there if you drive with the tilt open?

 

[JakeCs]

@BenF
I seem to have exact same problem by the 'sounds' of it. I got all parts of suspension and brakes checked by two different mechanics but they couldn't find any problem.
It more noticeable at low speeds because of its low volume

 

[Wombat457]

I have a similar problem with my 2007 E350. Periodically I get a "thumping noise" any time I go over a pot hole or any other significant issue with the road surface that sounds as though it is coming from beneath the rear of the car. It sounds very similar to the exhaust hitting the bottom of the car, for example. I have had the issue looked at by my mechanics and they found nothing amiss with anything, not the exhaust, the suspension, wheels, steering systems nothing at all.

In hindsight, I wonder if it might be the battery has come loose in the boot and it is that which is "jumping" when hitting a rut imperfection and the sounds are being transferred to make it appear as though they are coming from beneath our vehicles ?

 

[JakeCs]

I saw a video by Scotty on YT using a multiple microphone device to find sound sources. I tried that with a single microphone but the regular noise underneath the car drowns every. other sound.

I do suspect it might be the amplifier unit in the rear right, or rear headlights or maybe a loose plate underneath the car.

 

[simmon01]

I saw a video by Scotty on YT using a multiple microphone device to find sound sources. I tried that with a single microphone but the regular noise underneath the car drowns every. other sound.

I do suspect it might be the amplifier unit in the rear right, or rear headlights or maybe a loose plate underneath the car.

Hi Jake, curious about if you sorted this noise thing. I had something very similar last year, was told all was ok and because it sounded like it I decide to change the anti roll bar links and really torque 'em up tight! Smooth as butter now. Also had something very similar on another 211 couple of years back which was the front suspension top mount, just the ball joint on a triangular bit of steel/ally, not the big U shaped piece it bolts on to.

 

[JakeCs]

Hi Jake, curious about if you sorted this noise thing. I had something very similar last year, was told all was ok and because it sounded like it I decide to change the anti roll bar links and really torque 'em up tight! Smooth as butter now. Also had something very similar on another 211 couple of years back which was the front suspension top mount, just the ball joint on a triangular bit of steel/ally, not the big U shaped piece it bolts on to.

No, its still not fixed, I have visited many mechanics and everyone gave different opinions and ‘fixes’. one mechanic told its front upper strut mounts and also suggested shock absorbers change up front. he did tighten up many nuts and bolts underneath before giving his investigation results. One had told its front shockers + link pins.
due to different opinions, I have ordered a car noise finder device and will be hooking it up when it arrives to find the exact source before going to mechanic for repairs.
any links or pictures or videos as a reference to your fixes i.e. anti roll bars and front shockers top mounts ball joints?

 

[Ajgolding]

One for the W205 owners - any of you had any rattles from the rear like the below?

From the clip, you can hear the rattle most clearly between 2-6s then 8-12s 16 and 22s as I drive down a local road. There's a little noise from the mobile phone holder but what you can mostly hear is the noise.

Video including vibration noise

Car has been to Mercedes ( had two new rear shocks, one was blown and could be knocking but wasn't it ) and a local Indy and they tried tightening up the boot lid fit (Indy) and some panels below the rear seats ( Merc ) but that hasn't cured it. I did take the plastic covers off the lower suspension arms too but that didn't help either.

I've had it up on jacks and had a good look around but didn't see anything obvious. Sounds to me a bit like plastic/metal especially as it 'vibrates' going over bumps. Apparently drop links etc all under the car are are OK, have removed everything from the boot etc. Are there any common known areas to check?

Hi, Did you manage to find the cause of this? We have a GLC and have a knocking noise, can mostly be heard when doing under 30mph. We’ve had the anti roll bar links changed before and it seemed to stop but now is back again. Unfortunately with the way the roads are I’m not sure if this is going to be an ongoing problem. Would love to hear if you sorted it? Thanks.