Best way to find suspension knocks?

[ps2cho]

On my 2008 E350 4matic it started making a pop/knocking noise on the front drivers side suspension. I have 120k on her now.

It only really does it when I back out of my driveway and begin to turn. No noises on acceleration or turning including when the weight shifts -- it seems to do it at low speed when I reverse out of the driveway and am slowing down to put it in drive.

I replaced the lower ball joint and lower control arm about 10k ago...
Sway bar? Upper ball joint? Steering tie rod? Axle shaft? How can I figure it out when there is nothing visually obvious and all bolts are tight?

since I can't find anything obvious I don't know really the best way to figure out which part is making the noise.

[tyl604]

My 81 300SD began knocking on the expressway like that. Do not remember if it had to do with speed or not but I think it mainly came after hitting a bump. Went on for several months. Everything drove fine and I never knew when the knock would start. Replaced the front shocks and it went away. Maybe your shocks??

[oldsinner111]

Jack body up till tire is free from ground,use crow bar to lift tire,Use rubber hammer on,sway bar,and end links.Do not replace with chinese parts,they only last a year.velocity joints are bad for poping in turns

[ILUVMILS]

FWIW, upper ball joints and sway bar links are the most common causes of F/E knocks on RWD 211's. You can disconnect the sway bar links and see if the noise goes away. The upper BJ's are easy to check as well. With the suspension hanging just reach in and give 'em a squeeze by hand, that's all it takes.......

[Stretch]

Slip plates

[ps2cho]

Bumping thread...haven't driven the car much, but I want to get this figured out as I am still stuck.

Here is a video:
You can see it pops as the suspension settles even when going straight, with even a small decline. It pops louder going off the curb
https://www.youtube.com/watch?v=agJkniG6TZg

In the video, this is with the SWAY BAR DISCONNECTED. So that should completely eliminate the sway bar bushings/links (both end-links are new anyway).


This is what I have done so far:
Disconnected sway bar
Upper + Lower Control Arms
Upper + Lower Ball Joints
Steering Rack bushings
Engine Mounts and Transmission mount

[Diseasel300]

From your video it looks as if the noise is coming from the front-right corner (passenger side). I'm not familiar with the W211 suspension, but it sounds like something rubbing. Any rubber bushings in there that could be lubed with silicone spray? Don't discount the shock absorber...

With a noise like that, you should be able to replicate it by pushing firmly on the corner you suspect the noise to be at.

[nulu]

If all bushings are good , sounds like shock, they make a tool called chassis ears that allow you to connect to suspension points and then you can listen with headphones to help you narrow down the source, buy or borrow them

[ps2cho]

Long bump, but just got done putting brand new MB struts, new MB springs and shock mounts for both sides. Unfortunately NO change in the noise.

I was doing some thinking and I may go buy a car suction mount for my go pro and maybe that would aid in as a diagnosis tool to figure out which side its coming from.
I've figured out I can replicate the noise by doing sharp heavy braking and then immediately letting go -- just basically throwing the weight of the car forward for a brief second. Clunks every time I do this.

Driving me crazy!!

Quick summary update:
-Disconnected sway bar, so noise is NOT related to sway bar.
-Upper + Lower Control Arms
-Upper + Lower Ball Joints
-Steering Rack bushings
-Engine Mounts and Transmission mount
-Shocks, Springs and mounts.