SethUK

I have an issue or maybe it is ot an issue with Air suspension in my 2011 q7.
After longer drive and turning off the car there is a noise of escaping air from air suspension. After a bit of time the noise stops about 10 15 min.

Car has been in a garage for 2 weeks and they have replaced the air distribution module for £450 which resolved the error in the system, but the air still escapes.

Would anyone have an idea how to truble shot this?

The car doesn't lower itself etc, but I do ot think that is a common thing.

Looking forward to hearing about it more. Thanks

'10Q7TDI_Prestige'

My '15 had a loud 'hissing' from same area, where the pump and valve-block unit are co-located, etc. On mine, the air compressor had actually blown a seal on the high pressure outlet line, so it couldn't hold pressure.

Obviously if your car is still leaking audibly, the shop that did the work either has not resolved the actual underlying issue, or have created another similar air leak during the replacement of the valve-block unit, which requires old air line fittings removed and a new, different style air line coupler to be implemented...this requires lines prep and trimming to avoid leaks, etc. The key item is that the car is not dropping any height at one or more corners. That would mean the check-valves at each air unit and the unit's sealing o-rings are still in good shape.

Generally though, if there is a slow leak, such as you describe, then the air pressure loss is going to result in a drop in height at one or more corners of the car. Another possibility is that the storage tank air pipe is the leak source, which would not cause a drop in height so long as the valve-block is working properly. You can verify that easily via scan tool to view live data for the air susp system; it'll show you the system pressure stored in the reserve tank, etc.

Overall, not sure how it's your problem if you paid a shop to fix it and it still leaks air. Do be sure they used a high quality OE/OEM valve-block part and not a cheap knock-off part from China, as those are known to fail pretty quickly. If the leak is not super obvious, then a solution of dish-soap water in a spray bottle is used to localize/verify the air leak source, etc. Pretty basic stuff.

SethUK

Thank you for your input 10Q7TDI_Prestige'
On UK model on the passenger side we have the air tank and after i have dropped my car at the local garage again they have dismantled that and they have found that tank had rust and a small puncture that is causing the air to escape.
The interesting bit is that apparently there are bits of metal within the tank that are blocking the hole from inside, and that is why the hissing sometimes appear and sometimes is not present.

Luckily garage normally uses OEM parts as these are parts i normally request, however the tank is £2000 brand new so i am purchasing used one from eBay for £30

I hope that after replacing the valve block and the tank it will finally resolve my underlying issue with the air suspension.

I will post an update if the issue will be fixed after I will receive the tank and garage will install it.

'10Q7TDI_Prestige'

Hmmm, just be sure you getting the correct part. I'd be surprised to find an aluminum pressure tank, even used, for only 30 British pounds...a big chunk of aluminum like that is probably worth more than that as scrap metal, if I had to guess. I'd also be asking the shop to keep all old parts for my inspection, as the main pressure tank is mounted inside the cargo boot of the car, and being aluminum, not likely to fail unless improperly mounted/insulated, etc.

I'm suspicious I am. Now the system's pressure accumulators, those are located under the car and could conceivably fail due to rust or puncture, but that's definitely not the same thing as the high pressure holding tank/ cylinder mounted in the rear of the car. Keep your eyes open that you are not being taken advantage of.

Good luck!

SethUK

The tank that will be changed is the one under the car. I was not aware that there are 2 tanks that could be changed.

I have purchased the tank in the picture below. Hopefully this is the tank under the car.
Should I do something to it to help it being protected from rust, damage etc? It does not come with insulation, hopefully insulation from current tank can be glued to this 1?

'10Q7TDI_Prestige'

That's the rear air tank/accumulator, which is mounted inside the underfloor storage zone in the rear cargo area. On my Q7, this one is mounted inside of the left-rear cargo wall, and sits just below the cargo floor. When I open the hatch in the load floor, (spare tire well/storage tray area, tire tools, etc.) it's located immediately to the left of the opening, etc. It's definitely not 'underneath' the car, but due to sunroof drains leaking, there is certainly the possibility of water reaching it, and it's aluminum, so it does need protection from rubbing against harder metals, or other abrasion, etc.

There's also a front accumulator, of a bit different design, mounted beneath the car, but in the front. Both of these serve to hold pressurized reserve air for quickly responding to anti-dive, load-leveling, etc. The rear tank is larger and serves as the primary pressure vessel/storage unit for the entire system, whereas the front accumulator is more specific in function and also more exposed to the external elements based on mounting point. If unsure, verify the part # required via the shop doing the work for you.