Leaky S8 lumbar support - can it be fixed?
 

It's beginning to annoy me that the lumbar supports in both my front seats (S8 Recaro Sports seats) deflate fairly quickly.

Having just read a thread on another forum about fixing a different design of Audi-fitted Recaro it has spurred me into investigative mode.
That seat was fixed fairly easily by dismantling the seat, removing the pump unit and sealing a crack that had developed in the plastic body at a connection point. I'm thinking that the S8 seats may use basically the same pump and have the same problem.

So does anyone have any idea how to get into these big heavy beasts (ideally in situ) in such a way that they can be reassembled afterwards?

The only way I can think of getting to the lumbar support air cushion and pump is to remove the sear pad, and then remove the middle backrest insert. Both are only hooked/velcroed on but the hooks are really difficult to get to.
This thread has some pictures.
I would remove the middle seat pad insert first, then the middle backrest insert (hardest).

I forgot, the inner seat cushion is zipped at the back to the backrest outer leather (the one with side bolsters).
This zip is secured at either end by big staples which have to be removed, it is a bit tricky to unzip.

http://forum.a8parts.co.uk/showthread.php?t=6302

I even posted in that thread, but forgot! :o

Welcome to my world! :o

I had this done on my D2 S8 in my first week of ownership.

There was no way of doing this in situ. On the bench it appeared relatively straightforward to strip it down and replace the cracked connection block. The part number for that was 4D0959931 and it was 3 hours labour to fit.

My first ever A8 had this fix done under warranty too, but it was a seat out job for sure....

I concur with your annoyance.

Its quite a rare occurrence for the seat to fail, might be worth considering a whole replacement drivers seat for ease of fix, or even buy a cheap crappy one to practise dismantling first.... +++

Resurrecting an old thread, I've been rummaging around online and identified the likely culprit, it's a unit with part number 4D0 959 931.

I've found a source of supply in the USA and have ordered one - new but at a "reasonable" price. When the weather improves I'll see if I can get enough access to fit it!

This is the little beastie revealed inside a seat:
https://nordicaudi.com/php/files/896135-DSC00286.JPG
Next stop, Google translate, it's on a Swedish web site...... ;)

Interesting Andrew. This assumes, I suppose, that the leak is in the pump unit and not the "inflating bag"?

There are two bags so it seems more likely it's the controller/pump at fault, online comments from people who have repaired various A8/S8 seats seem to confirm that.

I've no idea how I'll get to it though, from various sources I'm pretty sure it's high up in the back of the seat, on the opposite side to the headrest motor.
Looking at the seats it would appear that you have to lift the leather back cover off upwards somehow, or unstitch it at the back.

In Goran's old thread I think it's all wrapped up in foam so not at all obvious. http://forum.a8parts.co.uk/showthread.php?t=6302
I think it's behind the grey foam I've circled in this picture, or just to the right of it pointed to in the second picture:

That's a good idea.
I've had a very quick look in my Bentley manual but haven't yet found out what the exact process is, had to waste time updating the Virtual Machine software first due to Windows 10 "issues" so ran out of time. :tuttut:
Though that's a US-produced reference so did they actually have these specific seats?

Yes
(pretty certain)

Thanks Marty, when I get a chance I'll have a serious look at Bentley and see what it says about taking the seat apart.

I did spot a reference to Sports seats but I'm not sure that's them.
The more basic seats are a lot easier as the back panel can be removed relatively easily, exposing all the motors etc.

Not that productive really, it's still not clear but does look like it's not a DIY job and needs trimming tools and skills.

That said, the unit arrived today and is quite small, so I'm wondering if a trimmer could open up the relevant area to facilitate a swap and do an invisible repair afterwards?

Is this of any help to you?

Removing and installing lumbar support and head restraint mount.
Slacken off lumbar support.

1. Head restraint mount
2. Height adjustment drive shaft *for lumbar support
3. Drive shaft retaining ring *attached with anti-squeak pad - item 4 - to backrest frame using cable tie
4. Anti-squeak pad
5. Linkage
6. Input shaft *detach circlip - item 10 - and detach drive shaft
7. Lumbar support
* Removing - unfasten all cable ties for anti-squeak pad - item 4
- remove circlip - item 10
- detach linkage - item 5
- detach lumbar support from retainers - item 8 and item 9
- detach drive shaft - item 2 - from lumbar support
8. Retainer
9. Retainer
10. Circlip
11. Bolt
12. Cover


Removing and installing electrical components with backrest
1. Driver's seat backrest adjustment sender -F86
2. Driver's seat backrest adjustment motor -V45
Passenger's seat backrest adjustment motor -V46
3. Flexible drive shaft * for head restraint adjustment
4. Head restraint adjustment sender -G129
5. Head restraint adjustment motor left -V103
right - V104
6. Driver's head restraint downward adjustment limit switch -E196
Passengers's -E197
7. Driver's head restraint upward adjustment limit switch -E194
Passenger's -E195
8. Cover for head restraint adjustment mechanism
9. Valve block for driver's lumbar support adjustment mechanism -N209
Passenger's -N210
10. Pressure switch for driver's lumbar support adjustment mechanism -F224
passenger's -F225
*inserted in protective case - item 11
11. Protective case *for pressure switch and pump for lumbar support adjustment mechanism
*attached with double-sided adhesive tape to backrest frame
*sealed with cable tie
12. Pump for driver's lumbar support adjustment mechanism -V152
passenger's -V153
*inserted in protective case - item 11
13. Air cushion for lumbar support adjustment mechanism *attached on underside with double-sided adhesive tape


text 3.7 - Removing and installing pump, pressure switch and valve block for lumbar support adjustment

* Unscrew valve block for lumbar support adjustment -3- from backrest frame
* Carefully unfasten air cushions -1- and -2- from polystyrene panel (double-adhesive tape)
* Detach connectors to pump for lumbar support adjustment -5- to pressure switch for lumbar support adjustment -4- and to valve block -3- for lumbar support adjustment.
*Disconnect appropriate hoses.

Thanks for all that, it's basically the same as I get from Bentley and ElsaWin. But until you actually look at it in detail it doesn't make much sense.

As Goran posted in the other related thread, taking out the centre backrest panel, which looks not too difficult, may give enough access.

I'll put my findings up here as and when I tackle this, but it probably won't be for a while - weather is not good! :tuttut:

As some of you may have noticed, Goran has given me some more useful detail; in his thread (http://forum.a8parts.co.uk/showthread.php?t=6302 started about 5 years ago!) about dismantling the seat to get at the lumbar pump unit.
It's beginning to look less of a "mission".

One fall-back plan I now have is much simpler though. Having "rummaged around" a bit there is actually enough access to slide something into the seat between the centre backrest panel and the lumbar support bladders.
As I almost always had/have both those supports (when working) fully inflated I can just make up a pad of the right dimensions (about 300*200 mm and 50mm thick) and slide it in there, maybe with a bit of Velcro to keep it aligned.

Though obviously, as a D2 S8 owner I really do want it working properly. :ROFL: (Calm down IT!)
(If I fix this, which directly affects my driving comfort, I might even tackle my rear headrests next... :eek: )

And as luck would have it I had a 12" square of 1" thick seat pad foam, left over from replacing some dining chair cushions.
Folded in half and secured with duct tape it's the right size and a good test, though not quite as firm as the fully inflated bladders.
Worked it in behind the centre backrest pad and it feels much better now. +++

Edit: So much better that I've ordered a pair of the firmest (Severe, very firm) upholstery-grade foam pads, 12" by 6" and 2" thick with rounded edges, £9 delivered.

Arrived today, feel suitably firm, will slide them in when it stops raining - tomorrow maybe?

Edit: Put them in, needs a fair bit of force and wiggling as they are quite firm and the foam sticks to the seat and bladder materials; ideally need a fabric sleeve.
Not quite in the right place yet (maybe need to move down a cm or so, but still feel good +++ ) but with the rain increasing I gave up.

Had these in for a while now and they work well for me in the drivers seat.
However SWMBO doesn't like the passenger seat one, says it's too high up, so I'll see if I can adjust it.