Repair-It

Tough month for suspension. Spotted this as I was finishing the truck. Right front pretty low. I had just used the car to go to Home Depot, too. Nothing abnormal happened and the car had no warnings.
Long story short, good old fashioned air bag failure. They do age. I think these are original. Will post more but posting from EPC laptop for P/N reference.

Front right: A2213201838
Front left (if I replace in pairs): A2213201738

I'll just do the right front because that's the thing that's actually failed. Prices should be similar (but probably not identical) for the left front, should I decide to do the pair.

FCP Euro Bilstein ($1,173, lifetime): https://www.fcpeuro.com/products/merced ... -44-110475
FCP Euro Arnott ($764.35 + $200 core, lifetime): https://www.fcpeuro.com/products/merced ... arn-as2547
Rockauto Bilstein ($828.99, lifetime): https://www.rockauto.com/en/moreinfo.ph ... 56&jsn=568
Rockauto PRT ($340.79, lifetime): https://www.rockauto.com/en/moreinfo.ph ... 56&jsn=550
Rockauto SKP ($386.79, 12 month warranty): https://www.rockauto.com/en/moreinfo.ph ... 56&jsn=553
Rockauto Arnott ($554.79 + $200 core, 24 month warranty): https://www.rockauto.com/en/moreinfo.ph ... 56&jsn=562
Dealer reman ($1,111,50 + $125 core, 12 month warranty): https://www.mercedesbenzpartsshop.com/o ... 1320183880
Rebuild Master Tech ($293.95, lifetime for air parts): https://rebuildmastertech.com/mercedes- ... 213200538/

With the last one they can actually rebuild my exact strut. This might be the best scenario because then the shock part of the strut would match the wear on the left side. There is no duplicated effort going back in for a second strut so this might make sense, as long as I trust their work. It's basically a new air spring in my current strut, and the cheapest option. Understand that the Arnott stuff also results in used shock parts on a "new" air spring.

If I didn't trust RMT or whatever, I suppose my next pick would be the Rockauto Bilstein at a fairly spendy $829. I will not touch Arnott, or PRT or SKP. There are probably some cheap eBay options too, and they won't be going on my car. The dealer reman is out considering I can get an actual Bilstein for less, with no core charge.

Ok, I'm sure someone will ask. Here are some eBay options:
Suncore for $180.50: https://www.ebay.com/itm/385606766967?f ... BM_IbGqdBk
Shock Masters for $180.10: https://www.ebay.com/itm/162591420021?f ... BM_IbGqdBk
Used for $50: https://www.ebay.com/itm/256625152481?_ ... BM_IbGqdBk

And a bunch of other nonsense +/- $200 that I have no use for. Though, it is worth knowing that when it comes to keeping these cars on the road, there ARE plenty of affordable options, but OEM performance is not guaranteed.

Info from the RMT link:

RMT’s M221-R310-4WFR is a complete rebuilt OE Mercedes Benz S-Class (W221) 2007-2013 w/ Airmatic & 4Matic Only Front Right Air Suspension Strut. The part is first inspected as a core and ensure it is a true OEM unit. RMT does not rebuild any aftermarket parts. We then make sure the core is up to par with our standard, this includes but not limited to, shock rebound, alignment, electrical integrity, oil leaks, and more. RMT then tears down the unit and then replace anything that can go bad, this includes the airbag sleeve, any and all O-rings/ seals, and may include screws, ball joint(s), protective dust boot, aluminum can, and more. All of RMT’s air sleeves match or exceed the quality of the original airbag sleeve that was on the OEM part. Each of RMT’s components are thoroughly inspected before assembly. Every airbag sleeve is crimped in house and tested.

Notice: Airmatic & 4WD Only, Top offset plate is not included

A quick video of the leak (you can hear it): https://www.youtube.com/watch?v=79a4fccWreY
Same thing but with the wheel cut to the right for better access: https://www.youtube.com/watch?v=ET6EcUEeeEo

Detailed video showing the different DAS functions for the AIRmatic system: https://www.youtube.com/watch?v=P1TUxzjCPCg

Removed. Not too bad. I didn't use any instructions though I am not sure why I loosened the upper ball joint. Doesn't seem necessary. Only problem is, RMT seems to be out of stock of the front struts, or perhaps even the parts to refurbish them. They are in Fort Lauderdale so maybe that's another factor? I dunno, the rears are in stock so I don't think they are just closed.

I should have looked more closely. The car was undrivable so whatever, but I will have to call tomorrow and see what they say. Else, Rockauto Bilstein for a pretty penny.

I tightened the upper ball joint nut. 20 Nm (15 lb-ft) + 90 degrees. Just need a strut that has a working air spring...

Called RMT. Nice lady. They are able to rebuild the core, they just don't have any cores on hand. I paid my $293 and they'll send me a shipping label. This price includes UPS ground shipping both ways. Looking at 3 days of shipping, 3-5 days of rebuilding, and 3 days return shipping. Unfortunately this means the car will be out of commission for 2 weeks. Hopefully I get it back no later than 10/26.

I asked about the warranty and rebuilding process. Aside from the obvious (air parts), they do check the shock itself for leakage. If it is leaking, they will probably tell me the core is not rebuildable. If that happens I'll either order a Rockauto Bilstein, or maybe they will have a core in a week if I choose that option. They also will check the ball joint at the bottom. I think mine is fine but I wonder if they are capable of replacing it if it needed it. Or checking the grease situation. Meh. So now I wait for a UPS shipping label. Meanwhile I need to find a suitable box which could be difficult.

This box was a pretty good fit. I bought this jack back when the STS shift linkage rusted off and I had to jack it up to shift the transmission to get the car home. I think I can sacrifice the box for this task. Just waiting for my UPS shipping label.

It will arrive at RMT Thursday mid to late morning, on schedule.

Evidently my strut has been repaired and I already have a tracking number. Cool.