grubster

Hi, so Ive had this truck since March 2020, and currently have 48k on it. It’s a 2009 gl550. I’ve replaced rear shocks, and front struts w/ arnotts with air bags. Rear airbags are original. Car also has new tires. Car seemed to drive perfect after doing the front struts. Just yesterday I noticed when driving the car first thing when cold over a bump the car shakes side to side and feels very loose even not over a bump. Like I have a bad shock or stabilizer or something. Once the car runs for a bit, it goes away and drives perfect.

I assumed there are many parts not only for the air matic system ,but also the ADS. It certainly feels like it’s loose in the rear and car is not very controlled( a bit scary). I can’t image the car was designed to where you have to wait for it to warm up in the winter for the suspension to work right, so I assume I have a problem. Any ideas?

Max Blast

One of the few reasons I can imagine it feeling loose when cold is that the rear air springs loose pressure over night (or over time, depending how often you drive it).

Does the rear suspension sink over night?

grubster

No, the suspension was up and level. Anytime the car isn’t level, the minute I open the door I can hear it adjust even before starting the car.

Max Blast

Well, if you are riding on factory rear airbags you’re living on borrowed time.

any signs of leakage from the shocks?

grubster

Rear shocks are new (replaced at 42k) now 48k. Rear air springs are original I believe.

Max Blast

I suspect your bags are bleeding down ever so slightly, coupled with shocks that aren't actually ADS; but rather Arnott's take on ADS.
Maybe it is a combination, or one or the other - but the airbags take a minute to repressurize, and the shock takes a minute of input to figure out what setting they are supposed to emulate.

This can create a less than planted feeling my OEM ADS equipped 450 has.
But you'd also do well to get under and check for obvious breakage.
Another thing you can do is to try to push the back end side to side when cold, and see how that compares to when it has woken up.

grubster

thanks Max, I’ll check on that tomorrow. I know my fronts were replaced with arnotts as I did them. I’ll check the paper work on the rear and see, but I believe they are OEM. One question with airbags, if they aren’t leaking and holding air, is that all there is to it? Meaning if they aren’t leaking they are working correctly?

I will say I drove the car again while cold this morning and it was fine, so maybe it was a fluke or to your point needing some time to pressurize and I would do good letting the car warm up a. It longer when it’s cold out. I’ll check he paperwork on the rear shocks, but I believe they are OEM.

expl0rer

Arnott has two shock part numbers for ADS equipped x164 vehicles. If you opt for the new shocks, they're not true ADS, as MaxBlast already pointed. If you want the OE ADS functionality, you would need the remanufactured shocks from Arnott, or get Bilsteins, or, of course, you can order from the dealer too.

My 2010 550 felt loose as well when I picked it up year ago. Replacing the rear hydraulic shocks solved that problem for me. I'd check the shocks for leaks, even though they're few months old.

If you raise the suspension, it tends to be a bit rougher/more bouncy, compared to lowered/normal. I can't speak to raising/lowering with the button as I have the optional off road package which uses a knob dial for this function and I can feel the difference between normal height and off road level 2 or 3. Neither of the off road levels are meant for higher speeds, btw, so I don't run them unless necessary.

I would change the height to low and see how the rear feels, and same with high the next time the car is cold.

grubster

This is a bit upsetting to hear. What I don't understand is you are saying Arnott does have true ADS, even though they are advertised as having ADS. We bought the Arnott from the Mercedes Dealer and that's what the Dealer typically recommends even! Even more upsetting is every where I read was people recommending to use Arnott's, and this is the first time I have heard this.

Regarding your comment on the Raising\Lowering button, we NEVER use the "raise button" while driving. Occasionally I will use the "sport" button, which I assume might slightly lower the car, but it definitely stiffens the suspension noticeably.

I'll raise the car up and check the rear shocks when I get some time, I'm back at work today for the first time in a while.

expl0rer

I guess I couldn't say you shouldn't be upset, because I was there when I found out about the different part numbers for ADS functionality after I had purchased the new shocks. I actually found out as I was on the phone with Arnott about errors on one side pointing to the solenoid. I was told the new part number was aftermarket custom valved shock with resistors to defeat the airmatic error. The resistors are located in the solenoid housing. The remanufactured part number is OEM shock which is rebuild and refurbished. It retains the ADS function as designed by MB.

I'm debating if I should request a swap from my seller, or leave them as is. When I'm replacing the fronts, if I were to go with Arnott then, I'll be sure to get the remanufactured units, or Bilsteins which I understand are the OE supplier for MB.

Arnott buys failed ADS shocks as cores, so this is something to consider well. Did you keep your OE shocks?

I'm surprised your MB dealer has suggested anything other than OE replacement. Ask them for the Arnott part number which they installed, or look at the struts to see it. They may well have installed the remanufactured and you may have the ADS shocks.

grubster

Ok, I just raised the car up and dug around underneath.

The rear shocks clearly had a Mercedes Part Number and Mercedes Logo on the sticker. I didn't notice any leaks, but only could see so much. I'm confident they are Original Mercedes rear Shocks.
Now the fronts have surprised me, as my brother in-law has a shop and did the work and he told me specifically they are using Arnott's and have done many trucks using them and had good experience. There was clearly a Bilstein Label right on the strut, I Took a picture of it. Part number 44-156268. There is a second smaller sticker up near the top, but just had a barcode and number. Maybe Arnott is using Bilstein for the Strut and their own Airbag on top? After reading this post, I'm hoping they used Bilsteins and Not Arnott's, so maybe I'm good!

expl0rer

I'm sorry, my misunderstanding about the MB dealer recommending Arnott.

So you do have the Bilstein shocks in the front with ADS. Arnott would have their part number on the shock body, so they did not come from Arnott. The airbags on the front struts might be a different story. Hard to tell unless you see part numbers on those.

The leaks would be on the rear shocks. I could not see any on mine when I had looked, but there was some hiding under the dust cap which are located at the top of the shocks. I noticed it when I was taking the shocks off the car. One actually had leaked hard as I was installing an Arnott airbag in the rear, which prompted me to have the rear shocks replaced. I would try with some cloth wrapped around a BBQ skewer. Try to get the cloth under that dust cap and see if there would be any oily residue on the cloth. Cheese cloth works well for me as it's thin enough and I can do a couple of layers with it, or old thin cotton shirt pieces.

Wrap the cloth around the dull tip, not the sharp one. And be careful and gentle while moving the skewer around. I'm sure you'll be careful, but you don't want to poke holes in the dust cap. I break the sharp tip off for my own sanity when I use the skewers for exploratory surgery.

grubster

Awesome, so sounds like I lucked out with them Not using the Arnott's! Maybe they were not in stock the day the car was in so just got the Bilsteins! FYI, the Airbags are part of the Air Strut assembly, they did NOT buy separate Airbags and Struts and put them together. I went through that option and they didn't want to spend the extra time\labor to assemble the strut airbag and just bought the entire "Air Strut Assembly" I'm happy I did this as we were considering ONLY replacing the airbag, but I'm confident now the Front struts were SHOT, where I thought I was just going in for "Leaking Airbags". The car drove dramatically better after.

I'm happy.

The car has been driving fine as well lately, letting it warm up a bit longer (this is my wife's truck), but I'll see if I can poke around like you said to check for shock leaks. Unfortunately the shocks were done down in Florida, and I'm in Chicago now. They were $480 bucks each, so I truly hope they are not leaking as I doubt that shop would warranty the job out of state! My dad bought the car in Florida and that work done, and then i had it shipped up to Chicago. The only parts that have not been replaced that I can tell are the rear Airbags. So that might be the next job, but like I said, they don't appear to be leaking as the car doesn't "Drop" even after sitting for a few days without being driven.

expl0rer

Yes, the front struts come as one assembly with the bags. I can see why a shop would not want to mess with mixing/matching one from manufacturer A with the other from manufacturer B.

Chances are high that the bags are Bilstein as well, as you said.

Arnott is not a bad company. They offer lifetime warranty to their shocks, struts and bags. You have to do your homework and be sure you're ordering the correct parts. I didn't, obviously, so that's on me. I'm not faulting Arnott for having multiple solutions.

I also had a bad airbag which was "not leaking". It all depends on how the bag folds over the puncture, and how big the puncture is. For a few months mine would hold its height when parked for a week or two, until the rear started to drop after 2-3 days of no driving. If I drove the truck every day, it would not have been noticeable until later even. The down side is that when the bag unfolds and the puncture releases air, the compressor works harder to keep the pressure in the system to spec. This will wear the compressor off sooner - added expense to replace it along with the bags. I feel your pain about cold weather. I'm in Canada, East coast. DIY season is short here. I'd recommend replacement of both rear bags unless you can pinpoint which side it is with certainty. Then you can get away with replacing one only for now, but you'll be replacing the other side too.... sooner than later. Might as well do both, as it's easy DIY if you're doing it, plus you have peace of mind that the bags are all done.

Miguk_Saram

My 2 cents.

This sounds more like a 'sway bar link' issue than it does an air spring issue. If the vehicle feels 'unstable' (as opposed to just being bouncy, or rocking left and right) then check/replace your rear sway bar links. Easy DIY: