2010 cl550 4matic, 150k miles. Both front air springs, all sway bar links, both front rearward lower control arms have been replaced within the last 3 years. That leaves the stabilizer bar, upper control arms, front forward lower control arms. Has anyone heard their s550 or cl550 make this noise? even on smooth pavement it squeaks/chirps like this

the anti-roll bar bushes are a known issue since birth - the had a warranty repair to bond the main bushes to the arm - now the only way to get new Merc bushes is a new arm with pre bonded bushes

ARB bushes are a very common driver of unwanted noise on all cars, as the bush ages and becomes less flexible, it also tends to shrink back leading to unwanted movement, noises and reduced roll control (not sway !!!!). And with lots of age you get knocking as the ARB rattles in the bushes, with W221 tank being so heavy it came with truck spec parts and tens to squeak and graunch rather than rattle

so start with the stabilizer bar? I’m aware that the bushings are “vulcanized” to the bar. The stabilizer bar bushings would cause constant chirping even driving straight on smooth roads?

these things don't stabilise anything and cars don't have sway (that's for young lady's dresses) - they provide resistance to and slow down the rate of roll, hence have the real name of an anti-roll bar

if you intend to get new bushes fitted (fleabag sell fakes you can try and fit to an old ARB) then you can just squirt lube on them and see if the noise goes away ?

wouldn’t I be able to squirt lube on the current fitted ones and see if the chirping goes away?

I had EXACTLY the same noise problem and it was the worn out ball joints of the rearward (load bearing) control arms. You say they were changed within 3 years but perhaps they still are worn out. If the rubber seal boots break it is just a matter of weeks for the joint to be gone.

These suspensions with the double lower control arms are difficult to check for wear on these ball joints as it is darn near impossible to move the ball joints for wear inspection by hand force. You really need to remove one of the arms to do a good inspection.

This problem got me with my car as I was troubleshooting the noise. Both sides ball joints felt tight by normal "grab the wheel and rock it sideways" test but I saw the passenger side rearward ball join rubber broken so I ordered the part and replaced it. Problem got little better but was not fixed. Trying to rock the drives side wheel by hand again to feel any ball joint wear was impossible so I removed the rearward arm and it was very clear that the ball joint was totally worn out though the rubber was good. So, ordered the arm and replaced it. No more "chirping".

hey arrie thank you for this info. You say you were able to do this job by yourself? I might be willing to give it a try if it’s as easy as changing the air springs, did the axle need to be removed?

Lol

I though that's what I said ?
remember its not good for the rubber and might encourage them to slip out of position - but if prepared to replace, then nothing to lose

apologies, I misunderstood. At this point I’m considering replacing all the control arms and arb.

Mine is a RWD. Assuming your control arm mounts from the top to a hole in the wheel hub like in mine I would think you need to remove the drive shaft first but I don't know for sure. I can tell there is not much room for the ball joint in my car without the shaft so it is likely shaft removal is needed.

yea that’s one of the reasons I don’t want to do this job. I actually made a thread about it earlier and never got an answer. I’ll have to take a closer look

Since posting this I’ve replaced the sway bar, brackets, sway bar links, upper control arms, intermediate axle shaft and bearing. Chirping sound remains 😡 I have a brand new driver side air spring to install(the current fitted one is starting to go anyway) if that doesn’t fix it, I’d say you are 100% correct arrie although it could still be the thrust arm as well

Upper control arms? Do you mean the Thrust Arm?

Why didn't you change the Lower Control Arm, the likely cause of the squeaking?

No, i meant upper control arms. I was giving a run down of all the parts I’ve replaced so far. I didn’t change the lower control arms because they’ve already been replaced about 20000 miles ago

The Lower Control Arm is usually the squeak from hell culprit.

In this case, the chirping sound was resolved by replacing the air strut assembly. On 4matic w221/w216 the ball joint and air strut are one unit, on rwd models the ball joint is part of the lower control arm. so yes, it was the load bearing ball joint that failed

We’ve owned our 45K mile 2013 S 550 with Air-Matic for 8 years. Recently it started making random odd wooden/metallic squeak-knock noises. Almost like something is sliding around under the hood. Considering Arrie’s car is the same age as ours I’m going with his recommended fix and plan to have both reward lower control arms replaced. The procedure looks conventional, no special tools other than a ball joint separator (or a hammer). This video shows the job on an Air-Matic S Class.

I’m not going to do it myself cause I’m just not than young any more, but I do have a couple questions.

Do you have any recommendations for where to get the replacement control arms? One can buy a pair of control arms for under a hundred bucks on eBay. Are they any good?

Should the front end be realigned after the control arms are installed?

Thanks a bunch!

replacing the rearward lower control arms did not fix the squeak/chirp on my 4Matic because on AWD S-Classes the (load bearing)ball joint is built into the strut(unlike the car in this video and your car as well)..just wanted to give you heads up. I’ve heard good reviews on TRQ aftermarket control arms if you decide to go that route. And yes, it is advised to get an alignment after replacement.

Yes, I should have mentioned our S is a Base version,
I've ordered a pair of TRQ rearmost lower control arms for about $140. (One OEM control arm was over $300)
The local tire store that provided the new Michelin's and did the alignment gave me a bid for $300 to install both arms and another $89 to realign.
I'll report back after the parts are installed. Fingers crossed.

My 2013 S-class was totaled in an accident 3 months ago and I just found a new one to drive just last week. Lower load bearing control arms ball joints are gone so I ordered new ones from FCP Euro. Left side one is about $140 and the right side one $116. Don't know why the price difference. They are made by Lemforder that I believe also makes them for MB. I use FCPEuro because they have lifetime warranty on the parts.

In my car there is no alignment other than the toe adjustment if needed. The arms fit in place one way and there is nothing else to move for alignment. There are some after market bolt kits available for other than toe adjustment but as the car comes from the manufacturer there is no adjustments for alignment in front or rear other than that front toe.

Load bearing ball joint, that I am talking about, is in the end of the load bearing rearward control arm in the 4Matic just the same as in the base models. The 4Matic airstrut connects to the arm from the side where the base model strut connects from the top. Both of these have another ball joint but, but in my 2013 these second ball joints were in very good shape when the ones at wheel hubs were shot.

Had an interesting conversation with another tire shop. The shop owner is familiar with this issue on our vintage base S Class'. If I understood him correctly he said the lower rearmost control arm acts like its part of the strut, and breaking loads are particularly stressful on the arm bush.
He suggested and said he had good luck with a brand (don't recall) of control arm that uses a metallic rather than a rubber bushing. He claims they will never wear out.
Considering the TRQ control arms arrive tomorrow and because I don't want to give up any of the inherent S Class smoothness, I'm going to use rubber bushings.
The alignment seems OK, but it's been a few years so I think I'll have the alignment checked.
Thanks for the advise!

Just ask them to do the front toe alignment as they all claim they will do 4-wheel alignment when it is impossible to do other than for shops that know how to use the bolt kits.

The TRQ rearmost lower control arms were installed today along with a fresh alignment. The squeak, chirp, knock noises are completely gone, yeah!
The shop owner said he had the best alignment man in the county. I have to say the car does seem to track just a bit truer. They also provided me with a complete printout of before and after readings.
I'm well pleased, and appreciate the wisdom on this forum!