A8 Rear Right Air Suspension Leak Issue. I'm close to burning the car
 

Dear friends,

4 months of ownership into a D4 and it looks something like this: $$$$$$$$.

After replacing every single coolant gasket on the 3.0 TDI about 2 months ago, the car has decided to challenge my mental health again..

I went on an airport run to pick up my parents last week when the car decided to let go of the rear right air strut. the yellow triangle ! light came on the dash and it was game over. I had to pull off the motorway and got it towed home by the RAC. Once home, I noticed the rear right sagging and when the compressor was trying to pump it up. It was hissing (Initially thought it was because the rear right bag had blown.)
Long story short, another grand lighter and 10hrs of labour taking every single bit of rear interior to try and fit a new air strut in... Started it up this eve in hopes of the boat rising herself up under her own bit of compressed air.. to my dismay. It was hissing air underneath where the compressor is. Back to square one.

I am going to jack it up tomorrow (for the 100th time this year) and check the compressor area using soapy water and see where the hissing is coming from.

Ultimately my question is if any of you guys have had similar problems or know of any common weaknesses. that are worth checking out. I must say I've come back on here as my last resort. Last time there was a lovely chap on here that went under the name of MP4.2+6.0 and he was spot on with what he was saying. So I'm rolling the dice again and hoping there is someone out there with a snippet of advice that will help me from loosing any more hair over this car.. although its like crack cocaine when it works.

Thank you in advance.

here's some pics for entertainment purposes..

https://cimg8.ibsrv.net/gimg/www.aud...5524fa96a1.jpg
https://cimg7.ibsrv.net/gimg/www.aud...a6f15ab4ce.jpg
https://cimg6.ibsrv.net/gimg/www.aud...cbe8c8c015.jpg
https://cimg4.ibsrv.net/gimg/www.aud...6cb48c2bca.jpg
https://cimg2.ibsrv.net/gimg/www.aud...b49b464770.jpg
https://cimg3.ibsrv.net/gimg/www.aud...5141f9b487.jpg

Been there!
 

If you can hear it, you should be able to find it...
That being said, now that you had a leak, you could have introduced a lot of water into the system. You might want to dry and or replace the desecant...
I had a bad front right air shock and a bad control solenoid block... I pulled my compresser apart and inspected and dryed the desecant in the oven! Bought a new control valve and had my shock refurbished

There is a ton of information on this site and this very issue. Very common problems..
Good luck!

Hi Dude, Thanks for replying,

I had the compressor cover off today and I can confirm that one of the main black lines coming from the compressor somehow was blown loose. the little brass olive was off the plastic line. I cut the line and re inserted the brass olive with nut into the v block.

Once the car was running the air suspension finally raised. What I am now trying to figure out is, Did the air bladder on the strut fail on me causing the main compressor air line to come out due to some high pressure spike or did the line just came out causing the right rear to collapse. Either way if the line came out surely all 4 would be deflated rather than just the one specific corner. "you could have introduced a lot of water into the system" I hope I have managed to avoid that as the line was still in the V block it was just loose.

Cheers !

Take a pic if you can!
 

The solenoid block has individual solenoids. So one bad line would NOT allow the other three to drop. The solenoid block should be labeled as to what goes where. If you caught it quick, water should not be an issue, BUT if it ran with a slight hole in the air bag for a while then more than likely you would have some water buildup. Something to look out for.

If you still have the old air strut you can test. I just adapted mine to an air hose and pumped it up with an air compressor... You can see the adapter in the picture. The screw driver is sticking in the hole in the bag. You can watch it expand and you will hear the air come out of the blown air bag...
https://cimg1.ibsrv.net/gimg/www.aud...fe51280685.jpg
https://cimg8.ibsrv.net/gimg/www.aud...3d0d237578.jpg

FL - Front Left
FR- Front Right
RL- Rear Left
RR- Rear Right
P- Incoming pressure supply from the compressor.
RES- Reservoir tank located in the rear left of the trunk panel.

Clarification
 

When you compress air you also are collecting the water vapor in the air... the drying system is designed for normal operation... extensive operation of the compresser will create excess water and overcome the desicant... the water leads to other failures...
Just look for any signs of water... not sure how far i would dig...