pipes, compressor, bags, fuse and a relay!

onetwentie · #1 17th May 2014, 11:42 AM

Hi all

I have a very quick question after having read quite a few threads on here regarding troubleshooting a leak in the air suspension system.

where are the frikkin pipes??

I am trying to troubleshoot this issue with my 2007 3.0 TDI A8 and have thus far managed to establish:

the 40 amp fuse in the passenger footwell is fine
I have changed the relay in case

please help.

Also is it true that if I want to test the compressor/pump I can do so from the relay location by giving it live and ground to the correct terminals?

thanks all in advance.

Delboy · #2 17th May 2014, 12:56 PM

In order to diagnose your problem and any other general tinkering on these cars you would be wise to invest in vcds cable and software so you may scan for faults and test components on the car.

I'm not at home just now but I can upload some info on the suspension systems later or try googling for Audi a8 suspension ssp and and you will likely find a good explanation of the systems.

onetwentie · #3 17th May 2014, 02:15 PM

Hi Del

thanks for the info. I should have mentioned that i've had the car scanned and it did come up with suspension errors, one of which was 'leak detected in system'.

I've managed to test the relay and all is good there, but i'm trying to figure out how to actuate the pump.

Anyway, i've managed to remove the wheel and the liner, just about to try and remove the pump. I think Glyn did a write up of how to do that.

Delboy · #4 17th May 2014, 03:43 PM

I'm quite sure you could manually trigger the compressor but its much better to do these tests with vcds as you can see the output pressure, temp, and function each strut through a sequence of output tests which may help you find the fault quicker and easier.

onetwentie · #5 17th May 2014, 04:02 PM

Managed to get to the pump connector and figured out which cables are for power (brown one and red+white one), wired a battery to it but nothing.

Does this mean it's dead?

If I remove the pump can I still drive/move the car or not? if not is that because the pipe circuit is broken and hence will not be 'air tight' ?

Also once the pump is removed will the car then lower all the way to the ground?

thanks in advance

Delboy · #6 17th May 2014, 04:08 PM

Looking at the schematic in that attachment if the car tries to raise its self with the compressor remove it will drop to the floor as the will be nothing downstream of the solenoid block to prevent the air escaping.

If the car is still at a sensible ride height you could disconnect the cabling from the valve block, that would prevent the air springs from discharging providing there is no leaks of course.

There is something else you could possibly try but I can not say for sure, if you go into the mmi and put the car into jacking mode then it should not try to adjust the air in the system but you can not go above 9 mph so its not going to help if you have to travel in the car and would be best if you disconnect the wiring from the valve block.

onetwentie · #7 17th May 2014, 05:59 PM

Thanks again for the reply Del.

I've parked the car in such a way now that its not obstructing and so can stay overnight on a axel stand if necessary (or I can put the wheel back on).

I am going to attempt the removal of the compressor as I think it is suspect.

Incidentally where is this valve block you speak of?

PS I do have the car in Jacking mode anyway to be on the safe side, however I understand it may not be wise to drive the car until the compressor is back on the car.

Also does anyone know how loud this compressor/pump is when it is working? should I be able to tell easily that it is running/on?

onetwentie · #8 17th May 2014, 09:20 PM

Not sure if anyone else is following this but here's an update.

I've managed to finally remove the compressor/pump - following a write up which a previous member wrote on this forum, available here - many thanks to Glyn.

The write up makes more sense once you've done the job (if that makes sense), it's a little hard to do, but I managed it okay and i'm no mechanic!

Anyway, whilst the compressor was on the car I did try to actuate it by putting a +12V feed to it from a motorbike battery, and also the ground, but had no luck.

So just as I had put everything away (it had gone dark!), I wanted to settle my curiosity - I took the battery again and put the feed to the compressor; this is done by using the lowest of the three connectors. And what do you know?? the thing comes to life and starts choo choo-ing like a little train.

So; this means that the compressor is good. What does come to mind is that one of the VCDS scan errors mentioned something about shutting the compressor down due to something, so I wonder if the reason why it didn't actuate when I gave it the feed, whilst on the car was because it had the other two connectors still connected? in other words there is some condition which is causing it not to come on?

anyway, I'm still learning and quite puzzled.

Hope this has helped someone, and if anyone cares to explain this a little more, I for one am all ears!

Delboy · #9 17th May 2014, 10:21 PM

The fact the motor is still working is a good thing, you need to find the soruc of the leak and fix that.

Your compressor may still be worn out but as you have not posted a log from vcds or run output tests its difficult to say what the status is.

Theres a guy on ebay called bag pie andy that sells a seal kit for your compressor and it may be worthwhile to replace it as you have the compressor out already.

I have a gut feeling that you have an air leak by what you have said and the system has shut off.

There was another forum member with suspension issue that said it was shut off but there was never any real conclusion.

onetwentie · #10 18th May 2014, 03:17 PM

Hi Del

Thanks again for following the posts and replying.

Deffo good news about the compressor - man that thing was a nightmare to get out! (ended up purchasing some L type keys with Torx ends, a bit like allen keys) - wish I had had these for the job.

Anyway, I was also thinking about getting the bagpipe kit, but didn't know how to check if the piston ring thingy needed replacing? but yes, it certainly makes sense to spend the £20 odd quid since I have it out already.

The guys that did the scan for me printed out the logs for me, so I will see if I can take a snap and upload them. But yes it would hopefully prove worthy to try and diagnose the issue.

I am going to cancel my appointment with the garage tomorrow, and hopefully see if I can resolve myself... of course with the help of fellow forum chums!

I have also found these threads but unfortunately some of them do seem inconclusive.