californick

Front driver's air spring goes down. It is intermittent. I always leave it set at level 2 - do not play with this very often. Sometimes good parked for days (no driving) and sometimes will go down after shut car off for 5 min waiting for friend at a store. Airspring is 36k miles old (both front replaced at dealership 70k before I bought car, a 2001 tip). Took to my usual mechanic (independent but Audi factory-trained), he replaced seal - looks like big o-rings (not whole airspring) - result: worse if anything - seems to go down more frequently now. Actually when I went to pick up car from this repair, car was sitting at level 2 nicely and had been parked for hours no problem, as we were talking, I heard the sound of air escaping and before our eyes the car let all the air out of front drivers air spring very rapidly - went from level 2 to lower than level 1 in about est. 90 seconds. The deflation had started all of a sudden. Another thing I noticed another day: had heavy luggage in back, parked, shut off engine, removed luggage, rear rises. Go back a few hours later, rear is still high, has not self-leveled like normal and on this same occasion, front drivers corner went all the way down as well. Seems more like a level control issue than a leak to me with that behavior - any thoughts? How to test - I do not want to pay for new air spring and labor only to find this is a level sensor or computer issue. Don't know if mechanic scanned for error codes. Will ask. If control issue related, what codes would we expect to find?

all(over)road

In my experience at my bud's dealership...only one corner drooping is an air spring. Sometimes, regardless of when it was changed or how old the bag is....a rock or some other road debris may have punctured the bag whilst driving. Scheiss happens.

But, for sure, an air line to the front bag at the block could be the culprit too from your description. I have to admit we've never seen that before on any customers cars.

Get some soapy water, raise to level 4 and 'paint' the air spring in question and see if there are any bubbles. No bubbles on the bag? Go look at the block...but my bet is that its the bag. And they don't always leak all the time, sometimes if there's a hole and the bag like in a fold; it 'll leak intermittantly.

Could you tell where the air sound leaking was from?...the bag in question or under the car in the back?

Any chance your indy may have re-connected the air spring wrong after his attempt at a fix?

californick

Thanks for the reply Jimbo. The leak sound was definitely coming from near the bag in question. The thing emptied all the air from level 2 down to the stop in like 90sec even though it had been sitting there fine parked and shut off for at least a couple of hours. Its like to control system all of a sudden told it to let it all out. Not a slow leak at all. Been good since the last episode Sunday morning 'til now Thurs morning and driving it every day so I will withdraw my comment about it being worse since indy fix attempt but it still leaked twice right after he got done so v. likely the issue remains but is just intermittent...

californick

Consensus seems to be this will end up being an air spring leak but before I go and drop that cash, does anyone have any experience with this being an electronics/level/control/computer issue and has anyone ever found error codes associated with it? If so, what were the codes?
I'll definitely ask for a soapy water leak test as has been recommended but its also widely understood by forums it may not be conclusive if no leak found.

Karlos1

If you heard the air releasing from the front where the bag is, then my guess is it's the bag or something related to the installation of the bag, and not the level sensor. It's my understanding (and don't quote me on this, I'm not 100% sure) that unless you have a leak somewhere in the front, you shouldn't have any air being released from the front of the car.

californick

Ah ha! That is great input Karlos1 thanks. I will have a look at this doc http://www.volkspage.net/technik/ssp/ssp/SSP_243.pdf when I have the chance to see if I can confirm that air should normally only release from the rear of the car (or anywhere other than the front driver's side) and that will help the diagnosis.

californick

OK, according to http://www.volkspage.net/technik/ssp/ssp/SSP_243.pdf pages 20 and 21, the valves for each air spring (numbered N148-N151) are located in the valve unit near the rear of the car. So the sound of air escaping in front driver's wheel well points to a leak issue. Car in shop today getting tested for leak (again)...

Mr. Timewise

My Indy had used the wrong large diameter o-ring at the top of the shock tower (he re-used the original one, not the larger cross section ones provide by Arnott). Plus they used petroleum grease to help make a seal there. DO NOT USE PETROLEUM GREASE ON O-RINGS. Use lithium grease or Krytox grease. Plus they must clean the mating surfaces where the o-ring sits.

After my air springs kept leaking after an install by the Indy, I disassembled everything myself, cleaned up the parts, smoothed the mating surfaces, installed the proper o-rings, and lubricated with Krytox grease (I used "240AC" but GPL-205 or Krytox/Loctite RFE PFPE Lubricant are just as good in this application). I've had no problems with air leaks since then.

And BTW...the leaking air was up in the shock tower top where a spray of soapy water (actually Windex works best) would not reveal the location of the leak.

californick

Update from 7/2 - Indy could not find leak in offending spring but it was failing at the shop and could hear air escape. Leak not visible when car on hoist. I had an after-market (Arnott?) air spring from brother-in-law who has changed to steel spring kit and saved air springs. Indy put one in Sat 7/2. So far so good but a bit early to tell since days could pass no problem with the other one anyway.

californick

No issues in over a week now so looking good. Was it a leaky seal on the OEM spring (fixed with the reinstall of Arnott) or the actual OEM bag had a leak? We might never know... Anyway, original suspicions about a level control issue seemed to be on the wrong track even though some symptoms pointed to something like that.