My (strange) suspension problem
 

I posted this in my other thread but better to start a new one here. I have read virtually every thread on suspension faults but mine seems different as it doesn't appear to have a leak. When parked, it drops the NSF to the deck. No hissing and strut has been checked for a leak. The compressor pumps out 14.5 bar. There are no fault codes with VCDS. When I start the car, it raises the NSF to normal level and the car drives as it should. Headlamps are also at the correct level and the NSF level sensor is fine.

What else can I check? It's almost as if the car is telling the NSF to drop when parked (over time). I guess the valve block is left to check (is this under the inner wheel arch?) but I would expect to (a) hear this and (b) expect faults along with it struggling to rise.

Yes, it's behind the rear section of the arch liner, up against the bulkhead.

Mine was like this it was the strut leaking but there were no bubbles externally or hiss to be heard. The car would prediocally top it up from the pressure in the reservoir for about 8 hours.
I replaced the airbag and aluminium housing, the airbag was in perfect condition, I think the leak was at the internal o-rings

I replaced the valve block first to no avail that is easy enough, just need to be scrupilously clean when fitting the connections.

Thank you

Did you just chance it by replacing the airbag? Any fault codes?

Yes I chanced it. If I had my time again, I would perhaps get a knock-off Chinese new one for around £200 or keep my eye open for a decent-looking used one, such as from a 2008 or 2009, but sadly they go for quite a lot of money just to take a punt on a 10+year old used wear item.

The same goes for the knock-offs they are a risk too - how do we know the variable damping is all the same as OE specs?

Rebuilding mine was a pain to dismantle and when it was opened I found the damper had been leaking damper oil but continued with the rebuild as I already had the part and the air strut was already in bits. There is also a slight knocking on the front offside that has persisted for years which I think is the damper as I have replaced everything else at least once, so I might bite the bullet one day and go with one of the first two options.

I've been looking at these that were posted on the forum. They do a full strut too

https://aerosus.co.uk/audi/a8-d3/aud...pring-bag.html

I've seen the videos ad it doesn't look too bad...Did you remove the upper arms or undo the big nut and remove it that way? Still deciding whether to but the bag or complete strut.

Yes, I detached the upper arms from the car and left them attached to the strut.
Rather than cut off, I broke the electrical connector off by making it cold (upside down aerosol to freeze it) and then crushed it. This leaves the pins on the wires and new connector housings are easily bought on ebay and the pins clicked in.
Some people suggest loosening the big nut (42mm?) while it's on the car but it was not possible for me, I wasted a lot of time trying including grinding all around the socket to make it fit in the aperture - I think the angle of attack is not perpendicular enough. Off the car, the big nut needed an impact wrench and I had to take it somewhere to get it loosened. After that is not to difficult and there is plenty of instructions online such as on dognmonkey youtube channel. But there are no official instructions as it is not a repair ever done at dealers.

The connector is available from Audi too so at least I know if I have to smash it off I can replace it. Probably easier to take the 42mm off if the bonnet was removed but I'm not going to do that. Just got to find the time now and make a bit more space in the garage so the car can live there overnight should I run into any problems.

Thanks for all the advice and sorry for all the questions, I'm sure there will be more!

Just to conclude, it was the strut that was leaking, not sure where from but it's internal somewhere. I decided in the end to replace it with an Arnott one as genuine Audi was too expensive (circa £2k) and I wasn't convinced with the Aerosus as the reviews were mixed. Car was going to VRS Northampton to have the flaps done and so I asked them to change the strut over for me. Picking it up in a couple of days but they have told me it hasn't dropped since.