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The leaking side bolsters on my B7 RS4 have been annoying me for years.
It was fixed under warranty 3 years ago, but after a year it was leaking again.

Today i decided to tackle it. It wasn't as hard as i feared to get to the valves and i was pleased to find the problem and cure it for a few quid!! Much better than spending £160 per valve !!

First remove the recaro seatbelt loops, item 10 in the image. They are retained by tabs on item 8. I did it from the back seat of the car, gently levering item 10 up and away from item 8. Its common to break the tabs on item 8 doing this, as Audi did when they replaced my valves some years ago!!
So i am purchasing new item 8's. Next, release the leather. It pulls out of the retaining grooved in the backrest as shown. Releasing the leather all the way around the backrest, the seat cover can pivot forward. (I left the leather attached at the base). The lumbar pad is removed in this image, exposing the valves. The left valve (Item 7) controls the side bolsters. The right valve (also item 7) controls the Lumbar. To remove the valve, disconnect the connector and carefully pull the hoses off, noting their locations for re-fitting! After hours of investigation and leak tracing, i found this crack. (Circled red). (Don't remove the brass insert, it is not necessary.)
The crack is most likely caused by the the brass insert being too large and splitting the plastic housing open over time.
To fix, fill the cavity behind the crack and around the base of the brass insert with a 2-part Araldite or a similar hard setting glue. (in this pic i have the valve apart, this is not necessary) What i found interesting is that i had one leaking valve and one good. The leaking valve is stamped 2005 manufacture. The good valve is 2009. Maybe they improved it? When i re-assembled it, i noticed the lumbar pad plastic retaining screws that go into the white foam had worm the hole in the foam out, allowing the lumbar pad to slip down.
I re-filled the holes with expanding foam, should give it a few more years life. Hope this helps someone.

Impressive!!!

Nice write up and investigation

I did this a couple of weeks back, although I replaced the faulty solenoid with a new one - I've still got the old one in the bottom of the toolbox, so will have to pull it apart and check out the component failure. The last person to document in that sort of depth mentioned it was the rubber seal in their opinion, so will be interesting to find out (thread link below).

viewtopic.php?f=35&t=96867


For a skinny runt like myself who needs them at maximum inflation, it's nice to get them holding pressure again.

awesome thanks for the writeup,

not sure if my pump has gone as i dont hear it when i press S anymore

Nice guide. I remember reading that old thread that said it wasn't repairable so never bothered.
It is probably worth adding that each seat has 2 valves; one valve does the thigh and upper side supports, the other one does the lumber support so worth checking if both valves has gone before attempting repairs.

Surrey Sam wrote:Nice write up and investigation

I did this a couple of weeks back, although I replaced the faulty solenoid with a new one - I've still got the old one in the bottom of the toolbox, so will have to pull it apart and check out the component failure. The last person to document in that sort of depth mentioned it was the rubber seal in their opinion, so will be interesting to find out (thread link below).

viewtopic.php?f=35&t=96867


For a skinny runt like myself who needs them at maximum inflation, it's nice to get them holding pressure again.

I also thought it was the rubber seat, the crack only showed up with leak detector.

If it is the same on your old valve, you might have a working spare after some araldite

Let us know if it is...

Did this fix to mine yesterday ,worked perfectly

Mine are still going strong, but I suspect in time I'll be doing this - great write up

slowcoach wrote:Did this fix to mine yesterday ,worked perfectly

Nice one, glad it's working for other people. Was the crack in the same position?

I didn't remove the brass couplers to find out i just sealed round them all

Ok no worries.

I could see the crack with the brass insert still fitted. Just have to look really closely.

Glad its working out for you.

Awesome write up, I will be attempting this on the weekend along with a bumper alignment! Thanks!!

lugars4, I can be a bit hamfisted at times. I think I'm worried about making a dog's dinner when removing the seatbelt loops. How difficult is it? What did you use to prise them off?

Roughly how long did the job take. If I have a disaster I can't afford the car to be off the road as it's my daily.

Cheers.

Dolphie wrote:lugars4, I can be a bit hamfisted at times. I think I'm worried about making a dog's dinner when removing the seatbelt loops. How difficult is it? What did you use to prise them off?

Roughly how long did the job take. If I have a disaster I can't afford the car to be off the road as it's my daily.

Cheers.

put 2 fingers in under the loop and push up then pull out

I used 2 thin plastic paint scrapers and put one in the top and one in the bottom and it popped off pretty easy.