Allroad Air Suspension Compressor strip & repair

[Duggy72]

Can the leaks be patched or does it have to be a new bag?

[Phutters]

Can the leaks be patched or does it have to be a new bag?

A new bag.

It's an age-related issue as much as anything else. Typically the bags seem to crack and perish where the rubber 'rolls', so even if patching it did work, it'd likely only be a temporary solution until the same bag sprang a leak somewhere else because the rubber has lost the pliability it had when new.

It's not a puncture as such.

[Dscotty]

Hi Darren,yep sounds like a leak and if very small can be very difficult to find, I wouldn't bother with audi I guess they would only replace it with no diagnosis, good news is your compressor must be healthy if it lifts fast so that's good, but be aware it will combat the leak tiring it out over time so best to fix ASAP,it can be hard to find the leak as it only leaks with the suspension sitting at level 1, and it must be a very small leak as I assume it takes hours to sink, so it is not doing too much harm for now, one option to help look is with the wheel removed VERY CAREFULLY use a suitable trolley jack and suitable jacking point on the lower suspension arm/lower ball joint to simulate the cars suspension sitting at level 1, this at least allows you to use a sponge with soapy water to soak and look for bubbles at the same time, usually the lower area of the airbag leaks on the fronts anyway, if it were an airline or fitting it would leak at every level so your description does point to the airbag,if it sinks every time left overnight at level 1 this is 99.9% the airbaggood luck best regardsAndy

Hi Andy,

great advice as always! We did take the wheels off with a jack under the balljoint to get better access, but this did not yield anything either. We spent 8 hours buggering around with it, spraying need bubble liquid on to it. The car is now parked at level 4, and staying perfect for two days, and can be driven without fault. Very frustrating, but whilst it is not causing any problems we will just run it over Christmas and take another look in the new year. Although with that 99.9% certainty of it being the airbag, it is tempting to just order one.

Hope you and the family have a great Christmas and New Year, and thanks again for your help and patience.
Darren.

[colinryan]

Hi All - great thread - I would appreciate a steer with diagnosing my Suspension 'issue/issues':

I replaced the compressor (before I found your solution Andy) just before Christmas. Basically the car was running fine (although in hindsight maybe a little slow to adjust levels). Quite quickly I noticed it had dropped when parked over a few days and then one morning (all within a few days) it was down on its haunches and not raising. The compressor had failed.

The compressor was replaced and works well now (fast to raise/lower) BUT the car is sinking at the front overnight. Again I wish I knew about the cpmpressor kit would have saved me a fortune. I have tried to use jack mode to diagnose if my current issue is a leak on one side overnight but its not clear - the front of the car is generally down on both sides the following morning.

Before I decide to replace two airbags (I would replace both with arnotts at same time if doing) I am wondering it there might be a fault other than an airbag leak that I should look for? Given that both sides of the front of the car drop in what seems to be the same way. One point of note: The car is parked on-street on a negative camber road overnight (not level) so this makes the diagnosis a little harder (harder to see if just one side is dropping)...

I have read the valve block can cause problems and am wondering if there is a way to diagnose if it is (a) the block (b) something in between or (c) the air bags themselves ....

All help appreciated - just want to know in what order I should check things - head wrecked !!

C.

[bagpipingandy]

Hi C.

99% an airbag leak, a car sinking is a leak, the compressor only tops up the air to adjust levels and sinking when parked is a leak,

probably just 1 airbag but to help diagnose further to prove it is the airbag before buying anything, try some of these:

park at level 4 overnight (it should not sink, if just a small leak)

park at level 1 overnight (it will always sink)

if the above is true it is the airbag itself leaking,

they leak on the lower half of the actual airbag and only on low levels 1 maybe 2 sometimes.

to check if both are leaking park at level 1 in jack mode (this dissables the system from adjusting) any corner with a leak will sink to the bump stops, the other side may dip due to the weight but if it sinks with the wheel in the arch that is the corner which is leaking.

final attempt use soapy water over the suspect airbag (mainly lower half) and PARK AT LEVEL 1 to search for bubbles (yes not easy to do!! ). it will not leak when the wheel is raised from the ground, not due to no weight on in but the airbag itself moves up and down to change the height,


if ony 1 leaks only change the 1 unless you have spare funds,

regards

Andy

[colinryan]

Thanks for the above Andy - the car wont drop (from jack mode) when left at level 4. At levels 1,2 and 3 it does drop over a few hours. It always drops on both sides - no discernable difference.

I am going to go ahead and replace the front bags. I am looking at the Arnotts units (standard ones).

Two quick questions to folks in general:

1) Does anyone have a current discount code for Arnotts if I buy direct ?

2) Does anyone know of a good reseller of the arnotts units (with the same 2 year warranty fro outside the US) who is cheaper?

Thanks,

C.

[bagpipingandy]

Hi C

does it sink fast at level 1?

pretty unlucky to have both leaking, check with soapy water before forking out,

as for codes I have seen a few but couldn't find any tonight!!,

also warranty is a grey area some say only available from arnott direct, you would need to contact vendors direct to see what they offer.

regards

Andy

[mat68046]

Hello Andy

Have spent the evening quality time with the 21 pages of this thread, thanks to you for good reading and resources.
I have a situational question but some other bit data first:
2001 AR. Used eBay replacement compressor.
Also LF replacement used locally sourced bag.
These two bits are irrelevant, really, just worthy of note.
Compressor still needs refresh with your new ring kit and I suspect one or both front bags buggered (nice colloquial term!). I typically drive this rig on level 2 but inevitably the front end drops to the bumps stops (although not every time, still mysterious there). Attempted soap bubbling which was inconclusive at level 1.
Scanned with VCDS and retrieved codes 01400 and 01772, the latter is the tricky one. Cleared codes and later obtained same result.
Under no conditions can I "get it up" (ha ha) to levels 3 or 4 anymore. Used to but I haven't pushed the system since changing the two components. I see no serious holes or tears in the rubbers.
Noticed while running a suspension output test while soap testing other bits that while the compressor was running air was escaping from what I think is the "pneumatic discharge" valve? White insert cap on the compressor? I'd expect it to be a pressure relief of some sort or bleed off but to leak while the compressor is running AND the car isn't at height??
I'll await your first response to this post; I have the car parked at level 1 for the night to see what happens...
Thanks for all the effort!

Mark

[bagpipingandy]

Hi Mark,

yes this post is even too long for bed time reading now!!

the description and codes point to a weak compressor,

but 1st, does the car sink when left at level 1?

if it sinks to the bump stops then you still have a leak, most likely an airbag

for the compressor:

the air escaping from the high pressure relief valve area (white cap) is strange, does the air constantly whoosh when the compressor is running?
has this 2nd hand compressor ever worked?
if someone has opened this compressor previously they may not have fitted the valve correctly if it has never worked, if air constantly sounds/leaks out when the compressor is running, try to trace where this air is coming from, using soapy water or listen may confirm actually where the air escapes from..

OR- (just a thought!! & more likely )
if this ONLY happens during the output tests the software may open the n111 release valve on the compressor to vent the air out so the compressor is being tested to run, not for pressure. if this is the case the air will be passing out through the large plastic "bent" pipe next to this "white cap"

perhaps to confirm this air escaping noise, best to check when the car is requested to lift normally (press up) the compressor should start and then listen to the compressor to see if the air leaks out. if no air leaking from the compressor or the front airbags, get a kit fitted to it,

best regards

Andy

[mat68046]

Hi Mark,

yes this post is even too long for bed time reading now!!

the description and codes point to a weak compressor,

but 1st, does the car sink when left at level 1?

if it sinks to the bump stops then you still have a leak, most likely an airbag

for the compressor:

the air escaping from the high pressure relief valve area (white cap) is strange, does the air constantly whoosh when the compressor is running?
has this 2nd hand compressor ever worked?
if someone has opened this compressor previously they may not have fitted the valve correctly if it has never worked, if air constantly sounds/leaks out when the compressor is running, try to trace where this air is coming from, using soapy water or listen may confirm actually where the air escapes from..

OR- (just a thought!! & more likely )
if this ONLY happens during the output tests the software may open the n111 release valve on the compressor to vent the air out so the compressor is being tested to run, not for pressure. if this is the case the air will be passing out through the large plastic "bent" pipe next to this "white cap"

perhaps to confirm this air escaping noise, best to check when the car is requested to lift normally (press up) the compressor should start and then listen to the compressor to see if the air leaks out. if no air leaking from the compressor or the front airbags, get a kit fitted to it,

best regards

Andy

You are correct diagnostically, I must have checked the "leak" at the compressor while VCDS was running the output tests. Soap test #2 shows no leak, and compressor rattles occasionally. This second unit never really functioned as new but since I had no reference (New to the AR) I didn't know what to expect. The original compressor, which I still have and will rebuild another one of your kits later, was worse in efficacy and noise.

Car was down on the LF front wing again this morning. Took system off of park and compressor kicked in (for soap test #2). Unit stopped running before the car reached level at #1, solid K134. Re-started car, compressor again cycled in and completed level to position 1 with no K134 activation.

Soap test #2 at the front bags did reveal perrish leak (position 1) LF at a spot I couldn't get to before, fairly significant. Seems I bought a holy bag after all.

Height measurements before any testing today were:
LF: 31.75 cm
RF: 35.5 cm
LR: 38.75 cm
RR: 41.75 cm

Assuming the differential in the rear height is due to the front left corner being so low.

Measurements at level 1 are a bit screwy (especially the rear) and maybe indicate calibration needed (?) but I'd rather wait until I change that LF bag and install the replacement compressor components. I don't dare try to see if the car goes to level 3 or 4 at this point, the bar needed to achieve that is seemingly exponential and with a verified leak not a good idea as I do need to use the car. Numbers are all over the place above and below 40.2....

LF: 37.5 cm
RF: ~38.1 cm
LR: 38.75 cm
RR: 42.5 cm

Thanks, Andy, for coordinating a chap in the States to route a kit to me directly, should shave off considerable time to receive it!
I'll post updates as they occur.

Mark