I am gathering information required to fix seat bladders in my 2008 W221. I have two problems - on driver side left lumbar side one is leaking, which is more of a nice to have thing for me - I like it flat anyways;
But on passenger side it is much worse: the central bladder is stuck inflated (or the previous owner did something to fill it out and left it that way). No matter what I do, I can't deflate it (comand, das, no effect), also the adjustment has a leak, you can hear air coming out, but I was unable to pin point the source just by looking at it from the position of removed back panel. Riding on passenger side is really uncomfortable thanks to this.

This guy made an awesome tutorial on how to address my problem 1:

But to address problem 2, I will probably will have to remove the entire seat cover to get access to the top central bladder. Does anyone know how difficult it is and what to expect?
The guy in the above vid did not go all the way to remove it, so makes me wonder why...

I checked several photos of removed seat (ebay) cushions and it looks like removing all the buttons frees the entire cushion and that should be it:





Any hints how to get on with this task?

Hi amg63dxb,

Accessing the side bolster air bladders is one thing. They are relatively easy to pull out and repair, in my experience. The lumbar and shoulder air bladders, however, are a bit more complicated. Theoretically, you could unfasten the clips that keep the leather cover in place and pull the whole thing up over the headrest to access the air bladder assemblies. If I remember correctly, the air bladders affix to the seatback, not the leather cover—but I may be wrong about this. Either way, I think this method will grant you enough visibility to see what you are working on.

I have previously repaired the side bolster air bladders on the passenger and driver's side seats, roughly following the tutorial you have shared. The shoulder and lumbar air bladders in my seats are not leaking—but are very selective and do not respond well to adjustments. They have gotten stuck a few times, but eventually, I can restore them to non-inflated. Maybe it will just take a bit more messing with to deflate them?

Anyway, if the computer detects a leak, it will prevent adjustment controls' usability in an effort to preserve the compressor, leaving you with whatever adjustments selected when it stopped working. At this age, the system can be quite wonky. In the past, if I inflated an air bladder too quickly, it will cut off the compressor because it thinks it is leaking.

Ultimately, I've found the air adjustments to be too much of a hassle, and that is why I have opted to stop using them altogether. If you are insistent on fixing the seat adjustment air bladders, I recommend that you use the Loctite adhesive intended for use on vinyl, fabric, and plastic. That is what I used to seal my side bolster air bladders, and it has held up for what has now been two years.

Keep me posted on how you end up tackling this and if you need more help. Maybe this will inspire me to go ahead and finally fix my lumbar and shoulder bladders too.

I'm done... all in all nice and easy job. The seat cover is held by two clips in the center of the seat, two springs and what was the most bizarre thing to me - a fabric tape around an airbag - it appears that this tape is being stitched after the installation, so there is no way around but to cut this fabric in order to separate the backrest from the frame. Removing the headrest is also straightforward - then you need to also remove the plastic guides for rails - and you can start detaching the seat back cushion.



Once separated, I managed to easily work on bladders. Mine have cracks in the inlet - the place where the air hose enters the bladder - not much can be done unless I can get something like a really strong adhesive and construct a small mold around the entire joint to fill it out and let it cure for a while... maybe I'll do this one day. For now - not a priority. I do not like the way it feels when it is all inflated (it's too tight for me), and I also do not use the dynamic seats feature, so who cares... The most important thing for me was to adjust that central set of 3 bladders making you feel like you are sitting on a football when all are inflated and two of them do not respond to controls. I managed to unlock/unclog valves by playing with DAS (inflating and deflating while squeezing bladders with my hand). After few tries it started working again and I am happy with the outcome.

I'll order this loctite you mentioned (thanks for the hint) and if I still have some energy left, I'll try doing it it in a week or two.