a2j

Hello. Trying to troubleshoot clunking noise that is coming from the front, passenger side.
Sounds very similar to this https://mbworld.org/forums/gl-class-...-problems.html
It got worse over the last month. Replacing sway bar links did not resolve this issue. But it sounds like worn out links. Did anybody replace sway bar bushings? How often? I still have original bushings installed. They look ok, but looks can be deceiving. This issue is very annoying. I refuse to leave it like that. Thank you for willing to assist.

DennisG01

Can you replicate it with the wheel in the air? Hands at 3:00 and 9:00, then 12:00 and 6:00... push/pull/twist and see if you can get it to make the noise. If you're lucky, you can and then you can easily find the culprit from there.

alx

i have it on my truck. i have replaced _everything_ as i have access and skills to do... anything.

still there.

hope you are luckier than me and find out your source lol...

i am very suspicious that the front stabilization bar bushings are softer than they should (even when new) and if loaded enough they will clunk.

make sure it is a clunk and not a knock. knocks are usually suspension pieces or end links. clunk is bushings. my clunk is uncurable as far as i am concerned haha...

a2j

The issue wasn't there before. This makes me think I can fix it, once I find what needs to be replaced. If I can't find anything more obvious, I will replace bushings and see what happens. It sounds pretty much like bad swaybar links, which I just replaced two days ago.... again.

alx

did you put oem ones? if you didnt i have seen the aftermarket ones fail almost immediately.

humor me - remove one end on each side (since you have done them a few days ago it would be very easy) and check how the little balljoints move on both ends of the links- they need to be snug and move with effort. also check how tight the bolts are that connect the links to the swaybar. if aftermarket some of them use smaller diameter bolt and they will move around even if tightened until you saw stars... (the "star" method of torquing things

DennisG01

Just to add something in regards to end links. I recently had a knock that sure sounded like an end link, but I could not replicate it by the motions I mentioned above. Try as I could, it just wouldn't make a sound. I couldn't see anything else that would explain so I took a shot in the dark and replaced it. Yup - it was the end link. But apparently, at least in this case, the knock could only be replicated with the suspension under load, not just with the wheel in the air.

You could also try swapping the left one for the right one and see if the sounds follows.

a2j

The ones I removed were Lemforder and the ones I installed are MOOG. So I went to check it, removed the passenger side link to inspect. It was still as new. Bolts were as tight as on the wedding night. Just as expected. Perfect size. OEMs that I removed after ~6mo of driving were loose. I never had an issue with aftermarket links failing on me in the first few months.

I guess I will try swaybar bushings next. Or could this be failing engine mounts? But it doesn't always makes that sound. Only at lower speeds, over certain kind of bumps.

YodaSyrup

There are multiple forum posts about X164's with a suspension knock/clunk on the right front side. The knock is usually most pronounced during low speed turns and bumps. While there are lists of suspected components to replace, there doesn't seem to be one definitive fix that is working for everyone. On my first GL, Mercedes replaced the sway bar links and the knock continued. Next, they threw everything at it - strut, knuckle, CV shaft and the knock went away. My second GL just started making the knock and my independant took the sway bar off and it still made the knock - so they are recommending the knuckle and CV shaft. I am getting a second opinion later this week and will report back. The more data people can log on this issue and what cured it for them, the easier it will be to diagnose this in the future...

YodaSyrup

Let me also add that everyone who has looked into the knock on my car has reported back that they are hearing it clearly, but they cannot find anything in the suspension that is loose, broken or unsafe. So it's really about an annoying noise and tracking down and fixing the culprit.

a2j

I don't think it's a CV shaft in my case as it doesn't make any noise when turning at any speed. Its more like rattling on small bumps in series. Not just one bump. Going over a large speed bump does not produce the issue.

alx

it is not a cv shaft - at least i have not seen it being the culprit on affected x164...

DennisG01

I once had another type of sound that I could of SWORN was coming from the front end. It was more of a vibration/clacking type sound, but would only happen at certain RPM's, even in neutral. It wasn't until I got fully under the car and had my wife tap the throttle over and over that I was able to find it. I just kept putting my hands on various parts (bracing/pushing, etc) until the noise stopped. It turned out to be a broken muffler hanger back near the rear wheels (the steel inside the purple rubber was broken). The sound was bouncing forward and it made it seem like it was coming from the front.

Now, I know this is not the sound you have, but it might not be a bad idea - it's easy enough, anyway - to take a close look at things in other places. It might be a wild goose chase in the end, but then again, you might get lucky!

TX07GL450

Have you tried to disconnect sway bar links on both sides and then drive? Make sure to not make any fast turns during this check. If clunk goes away, it was in sway bar system. If it doesn't go away, it is not sway bar (bushings or end links).

a2j

I was thinking of doing this. So, this would be my next troubleshooting step. But I won't be able to do it in the next 1-2 weeks.

BlownV8

Not sure if the shock was causing the clunk but when I put on a rebuilt front strut in it went away.

2010GL550

+1, I replaced sway bar links and the like with no success. Replaced the front strut/bag assembly and the noise went away.

It was very easy to duplicate, as there's a small bump going into our garage and you'd hear it all the time...until the new strut assembly.

a2j

My schedule for today was changed a little and I was able to spend couple of hours in the garage. I removed the sway bar and drove around. Issue was still there and seemed a little louder. what's next?

alx

A set of chassis ears

TX07GL450

+1 on chasis ears

Also have you tried doing this :
It might point towards lower ball joint. Lower ball joint problem also causes loose steering if it is "clunking" bad.

Basically possible reasons are upper or lower ball joint or control arm bushings. Another biggie is a bad front passenger strut. Try to bounce front passenger side and then stop. If it takes more than 1.5 bounces to return to baseline, strut might be bad. Do you know when was it last replaced ?

You can try to jump on passenger side foot rail and see if you can reproduce the clunk. If yes, a partner can look or listen the source of clunk.

I am sure you have done a close inspection of all the joints in that area.

If it would have been a creak/squeak rather than a clunk, I might have suggested to spray silicon on individual bushings one by one and test driving. Clunk is usually metal to metal sound.

I am not a mechanic or car professional, just know my way around cars a bit to suggest these few things. Hope it helps.

sak335

Check your rear end links too. Sometimes when the truck transfers weight, it can cause the rears to do it as well and it can make you think it's the front because the noise happens when you see the front end move.

My next attempt to fix this noise is going to be to replace the bushings on the steering rack. The one on the drivers side gets soaked by oil and it degrades the rubber. If replacing them fixes it, I'm going to make some out of polyurethane.

YodaSyrup

Took it to the dealer for a second opinion. They also removed the sway bar and lubed the control arm bushings, the knock was still there. They recommended replacing the right front strut, I did, and that did the trick - it eliminated the knock.

Since I'm the second owner, I also asked if we could review the prior service history on the car. There was a report of the same knock from the right front earlier in the car's life - another dealer replaced the right front strut and that must have cured it because the car did not knock when I bought it.

a2j

I replaced all of my shocks 80k (4 years) miles ago. Is it time?

TX07GL450

If current front struts has 80 miles on them, those would be prime suspects. Struts/shocks do wear out faster depending on how rough the roads are.

2010GL550

+1 that's what fixed mine too. What's strange, is that particular "corner" is now sagging a bit when left overnight. So it appears that there is a problem with the new strut assembly. It was installed one year ago this month.

a2j

roads are pretty rough up here. we pretty much don't have roads.
So I decided to check if my shocks are bad with a "jump around" method. Except this time I wasn't listening for the clunk, because there is none. And I have discovered a significant difference between driver and passenger side. I don't know if that is my issue with the noise, but my passenger side shock needs to be replaced. Front shocks came from Arnott, with airbags.