Hello,

I recently bought an Audi Allroad, with a compressor fault.
I was told the car has had all four airbags and the valve block replaced in the last 4years.

So I stripped the compressor, and found the cylinder worn aswell as the piston ring
I rebuilt the compressor using a very good cylinder from a Land Rover, and a new piston ring and rebuild kit.

The pump now seems to work great.
I have performed a 402 calibration with VAGCOM, and the car appeared to be coming together.

After leaving the car over night I noticed both front airbags go down.
Is there anything common to these? They seem to go down at the same rate.
My next job on these is to investigate with soapy water.

Now the strange fault I have, if I operate the car through all heights,, both rear sides stay at maximum height.
I've also tried the output test with vagcom, and the rears will not drop.

So I assumed the valves in the valve block might be stuck. I have inspected this and it does look very new, I also sprayed a little oil with PTFE in, and cleaned it out, As I know its a dry system.
With it being new is it likely both valves have stuck?
I suspect the car could have been parked up for a little while.

How does the system vent it's pressure?
If the valves are opening where does the air discharge? I'm wondering of this is blocked.

Sorry for the long first post, thanks in advance with any help and advice.

 

Hi, same reply as your other post

sounds like possibly 2 issues, is the error light on? what fault codes are present?

Affraid it sounds like leaks from the airbags at the front, if it sinks at all levels it is likely to be o-rings or the airline or fitting itself, do this test 1st,

both fronts will appear to lower as the other corner will sink to keep the car level so you may just have 1 leaking, does it sink all the way to the bump stops? A leak will eventually take the car to the bump stop

if you park in "jack mode" this will dissable the cars suspension and prevent the car lowering to keep level, then any sinking will show by the corner sinking down to the bump stop, (bare in mind if one front has the leak the other side has to take the weight of the engine so it will appear to lower due to the cars weight)

to answer your question where does it vent the pressure, it is back out the N111 valve on the compressor, it opens along with the valve block and vents air out through the large 8mm bent plastic pipe. so even if the valve in the valve block was not closing correctly air would then have to get through the n111 valve, so valve block is least likely for now

check it if sinks at every level, then if so we are looking for airline leaking or airline fitting or worst case top or bottom o-rings not sealing, if it only sinks at level 1 the airbags themselse are suspect to be leaking, soapy water is the best tool. remember the airline fittings at the valve block too

the rears not lowering is strange, stuck valves or wiring/level sensor issue is teh 1st thought, i wonder perhaps if tyre slime has been used on your car creating a lot of valve issues??
fault codes would be benificial to see if any electrical errors stoed

let us know what you get

best regards

Andy