S212 dismantles its rear air suspension

[MuffinClaw]

I let my car sit for a few weeks without driving it, and when I got back, the rear suspension had fallen entirely. It hadn't done it in five days, but now it did it again.
Starting the engine causes the suspension to pump up and remain in that position. Once it has landed, it will be level on all sides.

Is anyone able to explain what's going on?

[Lemmand]

Yes.

First things first:


1. Two rear bellows that are new.
2. A system of pipes that supply air to the bellows
3. A replacement valve block.

Beyond that, it has a ten-year lifespan.

[MuffinClaw]

Many thanks. It seems like you might aim the parts cannon at it. I am unsure as to whether the airbags on the left and right side are connected. Why does the car fall uniformly on both sides if one airbag or pipe is leaking? Assuming they are on distinct ones.

[ZappaZeek]

If you ask me, the valve block is probably to blame.

[Automan]

The airbags on my low-mileage 212 were leaking. Weak in cold temperatures, but fell uniformly on both sides. Never dropped again after replacement.

It can be more costly to experiment with the diagnosis technique when you're also paying for labor (multiple visits), therefore I'm assuming BlackC55's proposal is based on their extensive experience. If the air springs aren't going to last very long anyhow, and you plan on keeping the car for a while, replacing the pipes and valve block might be less expensive and less of a hassle than completing the job twice.

[EchoTrail]

Both of my 212s have been bellows, so I can say that from personal experience. You might try spraying the pipes and bellows with some soapy water, although it generally doesn't reveal anything. When parked on a level surface, both of mine would fall over. However, when I drove home on a tiny hill, they tended to stay there, even when the weather got colder. It takes my friend about three hours for her identical model to perform the same thing. The leak became too severe for our friend to continue inflating the bags; eventually, all four vehicles were affected.

Because they are a moving component, the bellows are where I would put my money for wear and tear. There have been reports of the air pipes rubbing against the subframe; the most cost-effective solution would be to replace them. Do a search on the forum; you'll find many threads discussing this issue.

[MuffinClaw]

The air bags can be replaced on your own, according to what I've read. How about the valve block and pipes?
Oh, and I used to build a Cobra using an RV8 engine that I rebuilt myself. I also have a great assortment of ramps, trolley jacks, axle stands, and tools.
Am I too old to do this? I'm 72 years old now.

Your responses are greatly appreciated.

[ZappaZeek]

I'd probably hire someone to do it for me when I'm 72 years old, just so you know. Of course, I'm not claiming it can't be done 🙂

The labor cost for the bellows shouldn't be too high, since it's the kind of task that would be much easier with a ramp rather than squirming around underneath.

[TypoQueen]

Both bellows are probably leaking. These things decompose at the spot where the rubber is fastened to the plastic block. On a 212, they're not too difficult. You can just wiggle the old, deflated bag out and the new, inflated one in; no arms need to be undone. The one and only real challenge is that the lower plastic block's holder in the lower arm can be somewhat snug at times. I use an air chisel to get them free, but not everyone has that luxury

[EchoTrail]

Similar to you, I enjoy rummaging around beneath my antique Porsche, but an independent Mercedes workshop does the majority of the work on my Merc. I saw that the labor to change the air bags was charged as 2 hours when I reviewed my invoice. It is up to you to decide... Are you currently residing in Kent or are you originally from Kent? I saw your name.