vtraudt

I would like to run a simple test, 'de-coupling' electronics from 'bags': I would like to inflate the bags interdependently with compressed air.

a) what outside diameter do the air lines have? I will try to find a 'slip over' tube to get me larger diameters to ultimately put a Schrader valve on or a 1/4" standard compressed air coupling.

b) Any idea what the air pressure in these bags are?

If I can 'lift' the car manually, but not with the system: look upstream (line, valves block, connections, electrical).

If I cannot 'lift' the car manually, take airbag (or both bags) out and do thorough leak test.

Alternative: try 'slime'?

vtraudt

OD of the plastic air line seems to be 4.0mm
The thread of the air fitting to the air bag has an OD of 7.8mm

What fitting/thread can I get to screw in there to pressuring the air bag manually? Or better of cutting the plastic line and later put a tube over it and double clamp it?

When disconnecting the front air bag fittings (car on stands, wheels in the air, suspension 'lock' NOT activated; car was all the way down in the front and several attempts to get prior to jacking it up failed):
front right left some air off (not sure if vac or pressure)
front left no air in/out

Mr. Timewise

You're out of my knowledge base now.

vtraudt

Huh! Was afraid this is going to happen.
Seems like most go the 'throw a 1/2 grand at the shop for new parts (bags, compressors, valve/control modules), something will stick.

Can't afford it (and goes against my grain anyway).

I need to build me a gizmo to connect compressed air to the air bags (existing screw in nipple).

Or cut the plastic line and later mend together. Would feel better about this approach if I knew what pressure we see inside those lines!

Is someone selling those nipples (and 4mm lines)?

Teutonix

Have you done the "soapy water" test for leaks on both bags, at different heights? I just replaced both front bags on my car this weekend. Only one was leaking, but the entire front would be dropped every morning. On the side that was leaking, I could hear the leak hissing at anything below level 3.

Don't cut the lines. You'll be asking for trouble later. If you can't find a fitting to connect at the airspring, have you tried to find one to connect at the other end of the line?

05allroad

As others have said, your symptoms are CLASSIC for a pinhole leak in one (or possibly both) front air springs. As a result, your compressor is likely on it's last leg, and may also fail soon.

I'd recommend starting with the airbags themselves. The easiest initial test is letting it sit overnight in jack mode. Currently, it's difficult to tell if one (or both) of your fronts are leaking unless you know what to look for (and look carefully). When your front end drops overnight, are BOTH front corners on the bumpstops, or is 1 on the bumpstop and the other @ L1? What happens is that as your leaking bag looses air, the other side will release air (intentionally) to level the axle. The good side will stop on L1, and the bad side will sink all the way to the bumpstop.

Another method of IDing the leaking bag is to leave it parked in jack mode. Leaving it in jack mode prevents the entire axle from leveling when one side leaks. This would mean that if you park it overnight in jack mode, ONLY the leaking corner should be down in the AM.

Once you figure out what side (or both) are leaking, you should go ahead with the soap test to find the actual bubbles. From there you can replace 1 (or both) front airbags, and determine from there if you've killed your compressor and need to replace it as well.

It's pretty rare to find problems in the distribution block or the airlines (although it's not unheard of to have a loose air line fitting at the bag). I'd troubleshoot the airbags before going nuts trying to diagnose the entire air system.

vtraudt

I spent a few hours today on the car.
The plan was to manually inflate the bags to eliminate ‘other’ factors (tubes, lines, fittings, valves, connectors, etc.).

I had measured the lines and nipple, but did not get input as to where to get those parts (also contacted Arnott, but their email listed on their website still (I told them some weeks ago) does NOT work (comes back with error); they are also notoriously slow to respond even IF they get emails)

I finally salvaged parts from my ‘shelf’, found the right nipple and built a ‘rig’ (screw in nipple, plastic line, 'slip over' hose, barbed compressed air connector).

With this contraption, I was able to inflate the front left (driver) air bag.

Doing the same on the right side did not get ANY air into the bag (stayed TOTALLY flat/crumpeled).

I then used a jack under the wheel to move it up down a bit (car on hoist), and then (sometimes) found a place where air inflated the bag.

Conclusion out of the observation:

a) Since both air bags CAN hold air for days, we are NOT dealing with a common/standard leaking air bag

b) Since I was able to inflate bags, we are NOT dealing with issues ‘upstream’, rather with the bag/bags themselves.
Current conclusion status: at least the front left airbag is leaking, but not from a pin hole, but rather from bad ‘seating’ of a seal.

Unclear: If just ONE airbag is flat, why is the other one not holding air (level controls system getting involved?)

Next step:

- Find out more about seating/sealing of airbag. Is there a ‘seal kit’?
- remove front left strut from car, take airbag apart
- inflate front left air bag and shut off (when inflated) air supply; load wheel up over night. See if it holds pressure (with level control system not involved)
- get prices for OEM airbag and upgraded Arnott airbag (in case new airbag is needed). Check if just one Arnott bag can be installed (or pair reguired).

Comments?

05allroad

Comments? Yes.


Again, leave it parked in jack mode overnight, and do a spray test with soapy water for pinhole leaks on the front bags

There is a seal kit that contains upper & lower o-rings, as well as the top shock mount for the fronts. It's possible that you've got a poorly seated o-ring, but your SYMPTOMS ARE CLASSIC OF A PINHOLE LEAK IN ONE OF THE FRONT AIRBAGS. Not sure how much clearer to make it. You're thinking about it too much and making it harder than it really is. I suspect that the airbag that wouldn't take air was in a position with the leak exposed, and when you used the jack to change wheel position, it moved into a spot where it could hold air. My solution for that (when I had the same exact issue) was to fill up the gas tank. What, you ask? Fill up the gas tank. The d/s front would hit the bumpstop, and unable to refill - unless I manually altered the height of that corner by adding weight to the opposite side (like you did with the jack). As soon as I'd fill up with gas, I'd be able to lift it right back up as if nothing was wrong.

The problem: a pinhole leak in the d/s airbag.

G'luck.

vtraudt

Again: if INFLATED/PRESSURIZED, it NEVER leaks. Not over night, not over 3 days AND nights.

But checking for leaks never hurts. The hole as to be at LEAST the size of a quarter. The amount of air I am able to inject into the air bag with my gizzmo inflates (as tried on the driver side) the air bag IN ONE SECOND (and that was with the flow limiter not even half open). On the bad side, I had it WIDE OPEN, air just RUSHING OUT (no hole felt around bag with hand).

I will spray soap water tomorrow, but I am pretty sure the only area the air escapes is to the bottom, along the 'shaft' of the air bag.

Who offers the seal kit? Does Arnott have one?

05allroad

I understand, but the thing is that they often only leak at a certain level. As mine was on the way out it could hold for months at L3, but would drop overnight on L2 or L1

If the air came rushing out, it should be pretty easy to figure out where the leak is!

If it's underneath the bag itself, you could have a problem with your lower o-ring

Hook up your compressor again, and see where all of the air is going. If it is the o-ring and you need a new one, both o-rings and the upper shock mount are in a kit. Audi p/n 4Z7 698 507