What "knocks" in the front end?
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From: Allentown, PA
'08 GL 320 CDI
Thread Starter
MBWorld Fanatic!
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From: Allentown, PA
'08 GL 320 CDI
The more I listened to the sound, I was kinda wondering if it was something else other than the steering linkage/tie rod. And I guess that's the main idea of this post... what else COULD make a sound similar to a bad end link?
I replaced the front right gas strut with an Arnott - maybe 3 years ago... 'bout 25K miles. I've had the car for 4 years and 'bout 40K miles and the front left has not been changed since I got the vehicle.
I replaced the front right gas strut with an Arnott - maybe 3 years ago... 'bout 25K miles. I've had the car for 4 years and 'bout 40K miles and the front left has not been changed since I got the vehicle.
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From: Emmett, ID, USA
2007 GL450
You have a part number or a spec for those o-rings? Mine leaks but it's so slow I'm not inclined to jump through any huge hoops to fix it.
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From: Toronto
2012 GL550
I had a similar problem in the right front with a phantom knock. Bought my 2012 GL550 used, not a month owned and the noise developed. The dealer changed upper and lower control arm, linkages, you name it but the noise didnt go away. Turned out to be the strut. Put in some Bilsteins and it went away. Actually got the idea about the it might being the strut from an old thread here.
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From: Allentown, PA
'08 GL 320 CDI
Look who thinks he's a comedian! 
I'll try and make some time this weekend to get the car back in the garage and jack up the front end, then use a 2x4 under the front wheel as a lever to "lift" the tire... trying to look/listen/feel for clunking.
I'll try and make some time this weekend to get the car back in the garage and jack up the front end, then use a 2x4 under the front wheel as a lever to "lift" the tire... trying to look/listen/feel for clunking.
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Thread Starter
MBWorld Fanatic!
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From: Allentown, PA
'08 GL 320 CDI
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2010 GL550, 2013 C63
It could definitely be the front shocks. I've gone through changing the sway bar links but knocking remained. Coughed up for two new Arnott shocks and the noise was completely gone. Yes, my GL has ADS.
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From: Allentown, PA
'08 GL 320 CDI
Signs are leaning towards the driver's side gas strut being the issue.
-- I jacked the car up and levered a 2x4 under the wheel. I had my son use the 2x to quickly raise and lower the wheel (simulating going over a bump). There was a noticeable clunking sound. I look, listened and felt every suspension component and it was definitely coming from the strut - and I did not hear/feel it anywhere else. There was a knock on the passenger side, but it was much, much less.
-- I drove around with the suspension raised and it noticeably decreased the amount of knocking while driving.
I don't think either of these things 100% verifies the strut as the issue, though, since when the front end is jacked up, the strut is at full extension... possibly changing the how/where pressure is placed on various components. But, it certainly seems quite likely.
-- I jacked the car up and levered a 2x4 under the wheel. I had my son use the 2x to quickly raise and lower the wheel (simulating going over a bump). There was a noticeable clunking sound. I look, listened and felt every suspension component and it was definitely coming from the strut - and I did not hear/feel it anywhere else. There was a knock on the passenger side, but it was much, much less.
-- I drove around with the suspension raised and it noticeably decreased the amount of knocking while driving.
I don't think either of these things 100% verifies the strut as the issue, though, since when the front end is jacked up, the strut is at full extension... possibly changing the how/where pressure is placed on various components. But, it certainly seems quite likely.
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NGL450 w/EORP, S550
Chassis ears are also immensely useful to find where knocks are coming from.
how I found my links to be knocking was by this method - thought it was the strut and was dreading $750 in parts - but then heard the knocking in the link arms clear as a bell.
if it is your struts hopefully they were arnotts that you bought = free lifetime replacements.
how I found my links to be knocking was by this method - thought it was the strut and was dreading $750 in parts - but then heard the knocking in the link arms clear as a bell.
if it is your struts hopefully they were arnotts that you bought = free lifetime replacements.
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From: Allentown, PA
'08 GL 320 CDI
Chassis ears are also immensely useful to find where knocks are coming from.
how I found my links to be knocking was by this method - thought it was the strut and was dreading $750 in parts - but then heard the knocking in the link arms clear as a bell.
if it is your struts hopefully they were arnotts that you bought = free lifetime replacements.
how I found my links to be knocking was by this method - thought it was the strut and was dreading $750 in parts - but then heard the knocking in the link arms clear as a bell.
if it is your struts hopefully they were arnotts that you bought = free lifetime replacements.
It's the strut that was on the vehicle when I bought it about 4-1/2 years ago. RMT brand. Supposedly, has a lifetime warranty - probably only to the original owner. New ones are $149. I did put an Arnott on the other side a couple years ago.
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NGL450 w/EORP, S550
In mine it was first the sway bar links causing a knock. Replaced them, then no more knock.
Then when I replaced the front airbags I hadn't tightened the nut holding the air bag onto the strut enough, but once I gronked that on star tight, no more knock.
I will say the two were significantly different knocks.
Then when I replaced the front airbags I hadn't tightened the nut holding the air bag onto the strut enough, but once I gronked that on star tight, no more knock.
I will say the two were significantly different knocks.
Last edited by Max Blast; Sep 10, 2020 at 09:52 PM.
Thread Starter
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From: Allentown, PA
'08 GL 320 CDI
I still can't positively ID where the knock is coming from. The only thing I can tell is that it doesn't appear to be other suspension components (verified by an Indy) and "most likely" it's something in the strut. But the Indy said there is nothing to worry about from a safety standpoint, so I'm waiting it out a bit to see if it gets easier to tell.
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NGL450 w/EORP, S550
I still can't positively ID where the knock is coming from. The only thing I can tell is that it doesn't appear to be other suspension components (verified by an Indy) and "most likely" it's something in the strut. But the Indy said there is nothing to worry about from a safety standpoint, so I'm waiting it out a bit to see if it gets easier to tell.
Thread Starter
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From: Allentown, PA
'08 GL 320 CDI
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From: Houston, TX
'98 E320 and '08 GL320
Don't mean to hijack the thread, but I disconnected my stabilizer links today, and it seemed that the knocking became rattling, so I am guessing that without the damping of the stabilizer bar, something is really cutting loose. I think I will get some of those "ears"--didn't know such a thing existed.
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From: Buford, Ga
2023 EQE AMG
check your steering rack bushing.. its really easy to tell.. once you have on some rhino ramps just turn the steering wheel and look at the bushing I just did mine on my GL350 today.. Kind of a pitb as you have to unbolt the front diff, then remove the small plates that hold the bolts for the steering rack then left and rotate the steering rack to get that one bolt out. When done reverse the direction of that bolt.
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NGL450 w/EORP, S550
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2010 GL350 Bluetech
check your steering rack bushing.. its really easy to tell.. once you have on some rhino ramps just turn the steering wheel and look at the bushing I just did mine on my GL350 today.. Kind of a pitb as you have to unbolt the front diff, then remove the small plates that hold the bolts for the steering rack then left and rotate the steering rack to get that one bolt out. When done reverse the direction of that bolt.
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Benz: 560 SEC, 2011 GL550 and other brands
on my GL I have a knock when in the max raised position going over uneven terrain. I was able to islate to an internal issue within the left strut. I can reproduce this knock when jacking the vehicle up. Its just as the tire starts to become unloaded the front left strut does a dull "THUNK" sound. it is originating near the top of the airbag area, but obviously something deeper inside.
Very rarely will i hear it knock in normal height position, only when exiting a steep upgrade driveway couple with a right hand turn-a moment when the front susp can go into full droop basicaly.
Very rarely will i hear it knock in normal height position, only when exiting a steep upgrade driveway couple with a right hand turn-a moment when the front susp can go into full droop basicaly.
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Joined: May 2013
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From: Espoo, Finland
2012 GL 350
I had a knocking noise at the front passenger side (this is an NA vehicle) and thought it was the anti-roll bar end links, so I replaced them. Noise didn't go away. At this point it was still under warranty and the next time I had to take it to the dealer for warranty work, I asked them to diagnose the noise. They said it was the strut and gave me a ludicrous price to replace it. I deferred, knowing the air spring would fail eventually and I'd replace it with Arnott. That occurred maybe 15k miles ago, and I replaced both front strut assemblies with Arnott. Jumped in the vehicle, excited to finally be rid of that damn knocking noise which had been driving me crazy for 50k miles....and it was still there. Ugghhhh!!! It's still there now and I can't figure out what it is. Everything feels tight when I put the car in the air.
I gotta tell you, I drive the kids to school every day which is in the center of Helsinki, and the roads are all cobble stones down there. That noise is going to be the death of me.
I gotta tell you, I drive the kids to school every day which is in the center of Helsinki, and the roads are all cobble stones down there. That noise is going to be the death of me.
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From: Germantown, MD
'07 GL450
Adding this for the record.
My clunking issue ended up being a combination of the sway bar links, and the sway bar bushings. Initially I just replaced the bushings - this resulted in a noticeable improvement in stability/handling and much less clunking. While I was replacing the bushings I noticed that one of the sway bar links was also loose, so I had to order replacements. Clunking gone.
Here's an easy DIY clip for the bushings:
.
While you're down there, you might as well replace the sway bar links also. Super easy and cheap DIY.
My clunking issue ended up being a combination of the sway bar links, and the sway bar bushings. Initially I just replaced the bushings - this resulted in a noticeable improvement in stability/handling and much less clunking. While I was replacing the bushings I noticed that one of the sway bar links was also loose, so I had to order replacements. Clunking gone.
Here's an easy DIY clip for the bushings:
While you're down there, you might as well replace the sway bar links also. Super easy and cheap DIY.
Last edited by Miguk_Saram; Nov 20, 2020 at 11:46 AM.
