Rear air suspension goes down

[bumble beemer]

I am aware that this is the A6 forum but thought I would post the question here as there are a lot more A6 forum users than A7's and the mechanicals on each car seem to be the same .

I purchased my A7 2010 3.0 Quattro with 50,000 miles and full Audi history approximately 2 months ago.

I have noticed that if I start the car and only run it for a short while e.g . Moving it from the drive into the garage or even just a 5 minute journey, the rear suspension drops within a day or two of not using the car.
It doesn't however seem to do this if I have driven it on a long journey e.g. An hour . This only happens with the rear suspension.

As this is my first car with air suspension, is this a normal characteristic? Everything else seems fine and it's a fantastic car .

[wildbore]

Hard to tell from this description. It depends how much it drops. Air suspension does adjust the ride height after the car has been locked. but it shouldn't slowly sag over time, adjustments are quick and precise (you can hear the air valves operating just after you lock the car if it is parked in such a way that a levelling operation is necessary).

The short journey / long journey thing makes no sense to me.

I suggest you park the car on flat ground and leave it for a short while (10 mins?) then measure vertically from the ground, past the wheel centre to the centre of each wheel arch (when I was having problems on my last car, I put a piece of masking tape over each wheel arch to ensure I could easily and quickly take consistent readings). Make a note for each wheel and then take further measurements over the next few hours / days. There should be no drop. If there is, the system needs to be checked and fixed.

Remember, though, that the car can rise or settle slightly as the temperature changes.

[bumble beemer]

Thanks for your response. I can hear the air valves operating. The car is always parked on even ground . The rear suspension sags significantly over time (approx 2 days) and although I am still monitoring this , it does 'seem' to be only sagging after a very short journey.

Once it has sagged , when I next get in the car , the rear suspension rises automatically to normal operating ride height .

[bumble beemer]

[wildbore]

Can't really see from your pic, sorry.

Anyway, here is a theory on the short / long journey thing: If your leak is bad (sounds like it, from what you say), then the car may be periodically dipping into the reservoir (there is a compressor feeding an air reservoir that supplies the system with a constant feed of air) whilst parked up to top up the air suspension. On a short journey, the reservoir may not be fully replenished and so it is quickly depleted once the car is parked up. On a longer journey, the reservoir gets fully charged and so is able to keep the air suspension topped up for longer, but the sagging must inevitably occur at some point.

But the reservoir tank shouldn't / doesn't take long to top up normally. If the leak has been going on for a long time, this may have over-worked the compressor, which might now be quite worn out and struggling to fully pressurise the reservoir. I view the compressor as a consumable, anyway - a lot of cars with air suspension seem to "eat a pump" at around the 5 year mark (well, MBs do and I am pretty sure it is the same system on both cars).

Worth looking into from the warranty point of view, perhaps, as pumps are around £500-£600 (that's an MB price, don't know Audi prices for pumps. Yet.). I don't know if there is a way to check or "benchmark" the pump's performance.

This is all just supposition, of course...

[bumble beemer]

Apologies picture was not very good . I would guess the sag, when it happens, is approximately 3 to 4 inches in drop.
What you are suggesting sounds plausible . If it had a leak , would it only sag on one corner of the car ?

[wildbore]

3-4 inches is a huge drop. Definitely needs to go back to the vendor. I don't know enough about how the system works to comment on the sag characteristics. If you want to PM me your email and I will send you a PDF of the technical description of the air suspension system. It may be helpful.

[wildbore]

Now the sun has gone in and I can see my screen better, I can see the sag in your pic!!

[Vrs_MAJ]

I have an A6 3.0bitdi, how do I know if my14 has air suspension?? Sorry for thread hijack. I maybe suffering from similar issues

Sent from my SM-G935F using Tapatalk

[wildbore]

On the MMI, press the CAR button. On the screen that shows a pic of the car and the various driver modes (comfort, auto, dynamic, individual), cars with air suspension have a option in the top left corner to "RAISE" the car (or "LOWER" it, if it is already raised).