That Sinking Feeling - A6 Allroad air suspension problems

[footfang]

Hi

I have a 56 plate V6 Allroad, owned for nearly two years now and it has recently started to develop what looks to me to be signs of a leak in an airbag. I took it to a local motor engineer and they suggested replacing the compressor pump - which was duly carried out but has made no difference. I then belatedly started looking at this forum and now realise that I may have wasted some cash - but hey at least my compressor is new:D. I'd be grateful for some help - I have read around the threads but am not quite sure where to start.

This is the story:

I have had four episodes of the rear suspension sinking down onto the bump stops. The first time it happened I got the flashing yellow and green lights when I switched the car on, and they quickly went away once the suspension pumped up again. The warning lights went off and all was well. I then had the compressor changed.

Now, intermittently, the rear suspension sinks, and it looks to me as though it's the rear passenger side that sinks first. The car would normally be in the "Automatic" suspension setting, and it always pumps up quickly once I switch the engine on. So far, the rear suspension seems to stay fine for a few days and then randomly collapses overnight. There are no warning lights when this happens. The suspension moves quickly between levels once pumped up.

How easy is it to access the airbags with the soapy water spray? can it be done without a Pit or ramp?

I'm not equipped to work under the car but I do have a sympathetic guy up the road who would happily do what needs to be done as a result of this enquiry.

Many thanks :D

[MarkTM]

Welcome to the forum!

I actually joined before I purchased my A6 :)

OK an earlier year, but don't think the technology has changed.

Replacing the Rear Air Suspension on the 2000-2006 Audi allroad quattro with Arnott Parts - YouTube (https://www.youtube.com/watch?v=RhGkhP9W_mY)

It does look like a lift would make things far easier, took me all of 30 seconds to find this vid

[bagpipingandy]

If the car always sinks when parked in "dynamic" the lowest setting, but doesn't sink when left parked at Automatic or higer then this is 100% an airbag leak, the rears have a gaitor and are hard to get soapy water onto the actual airbladder

I run a C5 and its the same theory for airbags, they leak at low levels due to how the rubber bends and if you bend perrished rubber the cracks are open and so air escapes, but lift the cars height, the cracks move upwards to the flatter section and so close and stop leaking

best regards

Andy

[gianton]

Check this thread here A6 Allroad 2006 rear suspension dropping (http://www.vwaudiforum.co.uk/forum/showthread.php/175296-A6-Allroad-2006-rear-suspension-dropping)


Sent from my iPhone using Tapatalk Pro

[footfang]

Thanks Andy - much appreciated. Airbags purchased and on in the new year.

Richard

[PaulF2.5TDi]

Hi Footfang,

Andy passed the same words of wisdom to me and was spot on - http://www.vwaudiforum.co.uk/forum/s...d.php?p=947784 (http://www.vwaudiforum.co.uk/forum/showthread.php?p=947784) is a write-up on how to change the airspring (sorry, no pics) it's not hard

(http://www.vwaudiforum.co.uk/forum/showthread.php?p=947784)

[Burlesy]

Thanks to bagpipingandy and his excellent posts I was able to fix my leaking rear airbag (A6 Allroad 2007) Replacement part ordered from Aerosus and fitted by my local garage all for half the price of of a main dealer, thank you Andy.

[bagpipingandy]

No problem, glad its all working as it should again. :)

Best regards

Andy

[54A4Avant]

My A6 Allroad C6 appears to have this issue, it will sink to lowest setting if left overnight in automatic mode, I've just run it up to lift mode and will leave overnight to see if it sinks or not. I've read a lot of the previous threads but still have some Qs.

What's the significance of using jacking mode when testing whether the car sinks from dynamic or lift mode overnight? At present I'm testing with jacking mode off, do I need to repeat the tests with jacking mode on?

Chinese eBay (Aliexpress) has air springs for C6 at around 100 US dollars plus half as much again in shipping. Has anyone tried one of these Far East imports, or is it worth paying more than double for an eBay uk item (given its probably made in China anyway?!).

[_Tazman_]

I'd strongly avoid aerosus, total cowboys, rubbish quality.. They supplied me phaeton air shock, all used crap.

Bought a new air bag on aliexpress, better or same quality bag as the German supplier, a 20 min job to swap out the bag once the strut is off the car.

Anybody with general mech knowledge can swap out their bags..... Compressors rarely go unless you ignore the symptom

Edit, I should. Add I own several other cars !! A phaeton is one of my daily's....

My A6 is a sweet ride.

[54A4Avant]

I've just ordered a couple of the Aliexpress air springs. Wil post pics when it comes. Total outlay was $225 incl delivery for 2 and if they're no good I'll be using the buyer protection which seems to work as well as ebay's.

[bagpipingandy]

My A6 Allroad C6 appears to have this issue, it will sink to lowest setting if left overnight in automatic mode, I've just run it up to lift mode and will leave overnight to see if it sinks or not. I've read a lot of the previous threads but still have some Qs.

What's the significance of using jacking mode when testing whether the car sinks from dynamic or lift mode overnight? At present I'm testing with jacking mode off, do I need to repeat the tests with jacking mode on?

Chinese eBay (Aliexpress) has air springs for C6 at around 100 US dollars plus half as much again in shipping. Has anyone tried one of these Far East imports, or is it worth paying more than double for an eBay uk item (given its probably made in China anyway?!).

Hi the reason to use jacking mode is this disables the cars ecu from performing any adjusting, as the car will constantly try to keep the car level, so if you have a leak on one corner the car will adjust and let air out the other corner to keep the car level, so by applying jack mode, only any leaking corner will lower all the way to the bump stops. Note: the other corner may dip as they take the weight of the car but any leak will show by sinking all the way down to the bump stops in some cases a leak is obvious at a specific corner, in other cases it looks like both corners sink so then use jack mode to confirm if it is both corners or only one.

I buy mine direct from china,

best regards

Andy

[54A4Avant]

Thanks Andy. I had the opportunity to park the car up in dynamic mode with jacking mode on this morning and have been keeping an eye on the back corners. It's now been parked nearly 3 hours and the back left corner is almost down on the bump stops. Back right corner is a little higher, so I'm not sure if that one is also leaking or if it's the extra load from the other corner. Will watch it all day I guess and then I'll have my answer.

For changing the air bags, this video shows removal without un bolting the lower suspension arm and seems to imply the new bag can be fitted the same way: Audi A6/C6/4F Rear Air / Pneumatic Spring Change - YouTube (https://youtu.be/0p8BB_j-srM) not sure if this is a good idea but certainly less scary than taking the suspension arm off?

[jrenoc1]

I did mine without unbolting any arms.

once I had car on axle stands( in jacking mode) put a long extension bar with a 10 mm socket between 10mm bolt at top of shock and lower arm.
This will hold gap so easier to remove and refit be bag.33073


33074

[54A4Avant]

Thanks jrenoc1, I will have a look when doing mine to see if I can rig up something similar. Did you hit any problems in changing the air springs, or did it go fairly smoothly?

[jrenoc1]

Only really pain was the bolt in base , get a good quality spline bit . I sprayed some release oil on it before I started so it had time to work. It's really exposed to road crap under the arm so I also sprayed the bottom in wd40 and usd a small screwdriver to try and clear .Place in spline bit in bolt and give it a good whack with a rubber mallet, make sure it's seated properly before to try to undo it, far to easy to strip. When refitting air line I counted how many turns to remove nut on new bag and did up the same so that the green line was lined up .

Other than that I just took my time , radio on , a few brews and bacon sarnie .33090

[54A4Avant]

Thanks, I will take care with the spline bolt and take your tips of wedging something in the gap to keep the suspension arm lowered and count the turns on the air line nut. I have both sides to do so will at least know what I'm doing on the second side I guess.

Do do you know what torque setting to use when tightening the spline bolt?

[jrenoc1]

To be honest I did it by feel ( bad boy) I'm sure someone here has the correct figure .

Youre correct the 1st 1 is the hardest , once you've done that 1 the 2nd is easier.

Ive done 6 in total now on different cars , all my own cars. The failing air bags used as a bargaining tool.

also replaced the compressor on my current allroad as well, surprisingly easy job.

[54A4Avant]

Sounds like i have a fall back option of hiring you to do the job for me :D Just kidding, with all I've read up on how to do this it seems easy enough (famous last words.

One last Q - for the air line connection, do you simply screw the old fitting dry onto the new air bag, or is some kind of sealing compound or Ptfetape called for?

[jrenoc1]

The new airbag should come with a new collar and nut. Will have a white piece of plastic in it , I undid the nut then compressed the air bag and refitted .
This again helps with refitting the new bag.
With a new Stanley blade trim about 5-10mm off the air line, a nice clean straight cut, then put the nut and collar on line , push into airbag so that the collar is at the correct depth on line and tighten up nut.3311233113
easy !!!!!!

[54A4Avant]

Thanks Jrenoc that has clarified things nicely and was helpful as I'm not used to working on pneumatic systems and didn't know how those parts should go together. The little bit of plastic in the airbag is sacrificial I guess. Just there to show how the parts should go together?

my air springs have made it from China to Liege so far, so soon with me I hope. Did you say it was a 150mm extension bar you used with 10mm socket on which you used to prop open the gap? I will have a look at the extensions I have here and see what I can assemble.

EDIT: sorry just looked st your original photos again and it's definately more than 150mm, perhaps 250 or 300mm?

[jrenoc1]

Yep it's a sacrificial piece of plastic, I thick it was 300mm . Can't remember, I just offered it up when the car was jacked up.

i looked at he Chinese bags but in the end ordered the aersus ones from Germany , embarrassing for the uk postal service. Ordered at 10.30 pm Wednesday and arrived by ups at 11am on the Friday .If I can help with anything else , just ask ����

[54A4Avant]

Thanks - my air bags arrived yesterday. Look fine to me, but the proof will be in the pudding. Seller on Aliexpress was Maxpeedtuning Store and cost was £87.50 each incl delivery.

Have you ever needed to perform a calibration on the suspension after changing out air bags?

[jrenoc1]

They look good, excellent price as well ����. Forgot to mention that when the bag is fitted I placed the lower suspension arm on an axel stand and the started the engine , turned off jacking mode and the bag reinflates , you need to do his to take the weight off the extension bar. Might be worth doing one side at a time. I did recalibrate the first time but haven't the last time, it's on the to do list but seems to be fine . I measured the distance on each corner after going through the different heights and they were all correct as per the tech info. Ross-Tech: VAG-COM: Suspension Level Control Calibration (http://www.ross-tech.com/vag-com/cars/levelcontrol.html) 33136

[54A4Avant]

Thanks, so did you have the car up on axel stands then added a third at the end on the lower suspension arm, or did you just move the stand from (where?) to the lower suspension arm? Hope that mine will also inflate up to the correct heights as I don't have VAG COM software / hardware. Only just bought the car and wondering if it's worth getting the diagnostics tool. Will probably cave in eventually!

[jrenoc1]

Had it on a pair of stands then moved to suspension arms. The cable , software is worth its weight in gold also worth checking to see if any of the guys on here are near you

[54A4Avant]

After refitting the new bag and connecting airline, am I right it's necessary to start the engine to inflate it? If so, is this still with jacking mode switched on? I'm a little confused over whether the bag will inflate while jacking mode is on, and if not then is it ok to switch off jacking mode while the car is up on axle stands?

edit: sorry Jrenoc1 I saw above you did say jacking mode should be switched off, but that the suspension arm needs to be on an axle stand first. What's the reason for the axle stand? Surely the bag will inflate and press the suspension arm downwards even whether or not there's an axle stand under the suspension arm.?

[54A4Avant]

Well I knew it was too good to be true, or rather they were too cheap to be good... Tried fitting the bags today, haven't got past the first side, but for both bags the problem is the same. They go in, they pump up, then I try to screw the M6 spline bolt in from below and find it will not fit. I know the thread is correct as the boot screws in nicely when the bags are removed from the car, so it's an alignment issue. The threaded inserts must be in just the wrong place, or rather just a bit away from where they need to be.

I don't fancy drilling out the hole in the suspension arm to enlarge it and although an easy fix, driving the car without the bolts in place doesn't seem too sensible, so I guess I have to try the Aerosus ones and get a refund out of aliexpress.

Any great ideas welcomed!

[bagpipingandy]

The aerosus ones are Chinese too,

the screw hole is in the centre of the airbag, inflating it before putting the screw in will likely move it out of position,

Try this:

deflate the bag make sure it's located properly, insert the screw then lower car and let it refill airbag,

Regards

Andy

[54A4Avant]

Thanks Andy, I will try it tomorrow. I'm not too hopeful as I only inflated the bag because I couldn't get the screw in, so I hoped inflating it would push the bag into the seat in the correct orientation and line up the home correctly.

[jrenoc1]

As Andy said the spline bolt is a real pain in the a..e!!! It may be the bag is not quite sitting right in the arm, every time I've done them getting that bolt in has been a pain. I think it's trying to refit the bolt without being able to see clearly what your doing , it goes in at what seems like a strange angle.

[54A4Avant]

Thanks, i remember the bolt did come out at a funny angle. Will try again today with fresh energy and with the spline driver canted forwards a little.

[54A4Avant]

Well the spline bolt went in ok in the end. The solution was to use a jack under the suspension arm to bring it up to a level position (rather than hanging down) and then I guess the extra weight the new air bag was taking snugged it down into the recess at the bottom and everything lined up. The bolt does go in at a funny angle. The driver bit needs to be angled inwards to the centre of the car and forwards, maybe 15 degrees each way.

New problem, although the new air bag seems to inflate, it is not rising up to full height and so the extension bars I jammed between the 10mm bolt head at top of damper and the suspension arm will not release. The car is still in lift mode and when I start the car and try to switch off jacking mode on the MMI, around 5 seconds later jacking mode switches back on.

If I knock the extension bars out of position and put the wheel back on, then lower off the Jack stands, that corner sinks to the bump stops. It's just not inflating properly and again jacking mode switches back on when I try to switch it off. Have checked the airline connection and its tightened fully and hisses when I unscrew it so I'm a bit puzzled what's going on... Leaking air bag perhaps?

[dan2485]

Check that the leveling sensor arm has not become detached or bent.

If it does not move then it will not inflate or deflate.

You will know what a leaking air bag will be as the compressor will be constantly running and you here the leak.

Google Audi ssp 242.

This give you good understanding. I'm not allowed to post up a link.

[jrenoc1]

Sometimes it can take a good 3 or 4 attempts for the bag to fully inflate. I unfortunately had the issue that due to the airbag failure the compressor destroyed itself. Mine inflated after 15 20 min of turning on and off.
How does the compressor sound?
smooth or noisey ?

[54A4Avant]

Thanks guys, the ssp241 was a very good tip and I enjoyed reading up on how the system works. I don't think the level sensor is damaged or misaligned on my car, I think it was just my misunderstanding about how the system works, as the car was still jacked up on the side I was working on when I was testing before. Today I took it off the Jack stand and partially lowered the car jack so the left side of the car where I fitted the new airbag was lower than the right, then I started it up and the car did come up, allowing me to remove the Jack fully.

Now jacking mode mode will switch off and stay off and the car is self supporting on all four corners. The back left corner on which I've been working is 10mm lower than the other side (745mm from ground to top of wheel arch versus 755mm) and ill monitor it over 24 hrs to see if it changes, before trying to swap the other side airbag.

Thanks for all the support, it's a bit scary doing "big" stuff like this on your own car, eh?!

jrenoc1, I cannot hear my compressor over the noise of the engine, or did you mean I should listen with the engine off? I have one of Andy's compressor repair kits and vague plans to recon the compressor after the dust settles from my airbag change, so if it is worn out hopefully it will be renewed before too long.

[jrenoc1]

It's a scary thing to start tearing apart our pride and joy, however the sense of achievement is brilliant.

I cycled through the heights a few times and this seemed to sort and calibrate if you don't have access to a Ross tech lead .

you shouldn't really hear the compressor, I just wondered as mine got really noisy before it killed itself.

The ring kit is a walk in the park after you've done the bags, best advice is to use a jack with a piece of wood on to support the compressor whilst unbolting it.

[54A4Avant]

Thanks - will get to the compressor sometime but it's not a priority. Results are in and having parked the car in dynamic mode overnight, the rear right side (which I didn't change yet) sunk to the stops as usual but rear left with the new air Spring is still carrying the car's weight, so I'll call that a success and move on to do the other side if I get a chance today, but certainly by the weekend. Will try to video it for future benefit of others, but getting some of the shots is going to be tricky.

[54A4Avant]

I did the second side today. Same song and dance routine trying to get the spline bolt in. The fix which worked on the first side (jacking the suspension arm up) wasn't working and in the end I had to use an inspection mirror and a Philips screwdriver in the hole to jiggle the threaded insert into line. I'm not in a hurry to do that again, but ultimately my cheap Chinese Aliexpress air springs have turned out to fit ok, hopefully they last.

i did take some video, but getting the right shots was a bit beyond me at times. When I get time I'll edit it and post up.

[jrenoc1]

It's a nice feeling when it's all done , a faff at times but ultimately you did it and could if you had to do it again.
when I got my allroad I knew the bags were on there way out and used it as a barginig tool.

i intended to get more photos but kept forgetting, although there's info about , there's not many photos.

[54A4Avant]

Just for a larf I asked a couple of local garages to quote for replacing the air springs on my A6 - to see how much I'd saved doing it myself. Both are part of a supposedly discount national chain, not main dealers. One quoted £950, the other £1,000 that was for replacing both rear springs.

Stressful though it was to DIY it, I'm quite glad I did.

[Kenhaw]

Hi guys

well I thought all was good after changing the piston ring but today the pump started acting up and only runs for 4 or 5 seconds and then stops. Does that mean the pump is bad? I took it apart again and checked piston ring and gasket and put it back together. On first try it ran maybe 80 seconds and on second attempt only 3 or 4 seconds.

Regards

kenneth

[bagpipingandy]

Can you get the fault codes?

unplug the temperature sensor if it only runs for 2-4 seconds and the compressor is cold the temperature sensor may be faulty, unplug it and test it

best regards

andy

[Kenhaw]

You mean just unplug the sensor and then try and run the pump again. I am in the south of france so its not really cold here.
It sounds like the pump is strugling and sounds more like it tries to push the piston but nothing happens. Piston ring is correct installed and piston runs free on cylinder.

[bagpipingandy]

Ideally we need the fault codes, however the symptoms of an overheating compressor is it will run for 3 seconds and stop, (not cold but hot) your compressor will not be hot but the temperature sensor if faulty is telling the system it’s hot, unplug the electrical connection to the temperature sensor and just try the system without it, else we need the fault codes

best regards

andy

[Kenhaw]

Hi Andy

worked like a champ unplugging the temp sensor. Thanks for all the advice

[bagpipingandy]

No problem, I’ve seen it a few times now, glad I could help

it will run without it but I recommend fitting a new one to protect it from overheating , I have new replacements drop me a PM with your email I can get one to you

best regards

andy