NolaGL550

During a recent visit to the MB dealer to have my Keyless Go control unit replaced, they found a leaking rear shock (not the airbag). Considering my GL has 75k miles, I am not absolutely surprised. Their quote to replace both rear shocks was "shocking" at $2600 before tax. I'm curious if anyone has attempted this repair themselves? Is there anything different when replacing the shocks (not the airbags) on an ADS (Active Damping System) equipped vehicle?

I did some searching online and found MBOnlineParts.com. They have the exact shocks (P/N: 166-320-09-30) for my ADS and Airmatic equipped 2013 GL550 at "only" $577.50 a piece (normally $770):
https://www.mbonlineparts.com/oem-pa...PWxheWVyXzE%3D

I found a video on YouTube that details replacing the rear shocks and the airbags on a similar year GL450 that I plan to follow and complete myself for just the rear shocks:

DC-BENZ

I replaced my w164 right rear suspension airbag and I would rate the job as being easier than a brake job.

Also, I would used http://www.arnottindustries.com/ instead of MB's. I purchased a new unit not a refurbished one. I think it was roughly $250.

NolaGL550

Thank you for your reply, but I'm not replacing the air bags. My X166 has ADS and Airmatic, which means there are airbags in separate locations than the rear shocks. The airbags are still holding air and have no leaks. One of my rear shocks is leaking from the seal and the entire bottom of the tube is wet and now caked with dirt and shock fluid. The video I posted shows the guy replacing both the shock and airbag, but I'm not sure if he has ADS on his Merc. I'm wondering if I need to put the vehicle in some sort of service mode like I would when changing the rear brake pads to reset the caliper piston depth. I'd hate to mess up a sensor on the shocks if they need to retract themselves slightly before I remove them. I'll definitely give Arnott Industries a look.

Jim Ma

No real difference just unplug the ADS connector on the shock absorber and they will install the same. Be careful as the pins in the plug are very thin.

NolaGL550

Thanks, Jim. At least it sounds pretty straight forward then. The only other question I have about removing the rear shocks is how to access the upper mount bolts. In the video I posted, the guy removes the rear armrests to access the shock mount. However, I am not certain this is the correct means. One of the replies to this video says that removing the armrests this way requires breaking the armrest tabs that connect it to the side panel. Is there a better means of accessing the top shock mount bolts? If it requires removing the side interior panel, anyone know where to find instructions, or know how it's done? If I can get to those bolts, I can accomplish this repair for half the cost.

Jim Ma

I just took off the interior side panel. It's held in with a bunch of clips and a few bolts. Just pop off the sill that is by the latch and then start working the plastic interior free. As you are prying it off you can start to see behind it and find the few areas that have bolts/ screws holding it on. Just take your time as you go it will become pretty self explanatory as it comes apart. Then you can easily access the top bolts to the shock. I believe there were under some foam but still easily accessible once the interior piece is out of the way.

NolaGL550

Thanks, Jim. I appreciate the guidance and will attempt the shock replacement soon. I'll post some pictures once I'm finished so the next guy can complete it more easily.

NolaGL550

I found some replacement shocks for ADS and Airmatic equipped GL series Mercs. They're from a company called Aerosus, and they currently list a pair of ADS rear shocks for $391 USD after their 10% discount is applied. Of course this sounds too good to be true, but I'm wondering if anyone has experience with Aerosus products. My intention was to go with an Arnott shock, but their website doesn't have the specific ones for my body style (166.873) ADS equipped GL. Any suggestions on reliable aftermarket shocks that aren't crazy expensive?

NolaGL550

Stay away from Aerosus! I found a bunch of reviews that say they break in a short time and are Chinese garbage. Instead, I found genuine Mercedes rear shocks with ADS capability on https://www.genuinemercedesparts.com for only $539 each. Not too bad considering the local Merc dealer wants $810 each. I'm ordering them today, so if they are indeed legit Mercedes shocks, I'll post their quality and markings. Just wanted to post this for anyone else in the same boat looking for quality rear shocks for their Mercedes GL (type 166.873).

NolaGL550

I was able to get time yesterday to finally install the new rear shocks in my GL. I'll post the full write up on its own thread here in the X166 forum. Overall, it was relatively easy with just a lot of tedious disassembly of the interior panels in the rear area, as well as removing some modules and brackets to access the top bolts of the shocks. After test driving the GL following the new shock install, it rode much smoother and took large bumps and ruts without the previous side to side hop that it had with the old worn and leaking rear shocks. Highly recommend trying this repair yourself if you have any previous experience with automotive repair.

DC-BENZ

Guess I should have read this first. So you reused the airbag?

NolaGL550

Yes, I reused both rear airbags since I tested them and neither was leaking. If you replace the rear shocks and want to replace the rear airbags as well, I'd suggest Arnott Industries. They have a great reputation, manufacture quality products, and have costs much lower than genuine Mercedes parts.