[maleksandersen]

My problems started a few weeks ago after the last fishing trip of the season. Car sat on a parkinglot over the weekend and the temperature went from 0ish to -20 or so. I started the car and got a running gear fault. I couldnt hear the compressor and the car hadnt sunk from any corner, so I figured frozen silica in the moisture trap was the issue. I drove back home and had the car sit for 3 days in a warm garage, but the problem persisted.

So I started calling shops and, no suprises here, they all wanted to start replacing parts. One shop offered to test the compressor first, so I took there. They replaced tested it with direct current and said it was broken. They quoted me a new one for 1400€ + work. So I asked if they would install parts that I provided and they said yes. So I ordered a new one from Germany for 430e + delivery and took it to the shop. They installed it and I got the car back. This had fixed the running gear error and car seemed to work fine.

The next day I went about my day, driving from jobsite to jobsite around the countryside for a total of 350ish km. I noticed the relay for the compressor was clicking often. I couldnt hear it running over the roadnoise but whenever I stopped I could hear the compressor running for 15 to 20 seconds, stopping and starting again every few minutes. So I got home and called the shop.

I took the car back with the understanding that the shop would check the system for leaks. The car was not dropping from any corner, but I figured it might leak from somewhere close to the compressor. They took almost a full day to check the car and found no leaks, but discovered that the air accumulator only had 3-4 bars of pressure in it. They tried to get the compressor to build pressure, but it wouldnt, despite running. At this point I had googled the issue alot and knew about the nitrous fill. I asked them to do it, but they didnt have the right tool to fit the accumulator.

So now I have the car back, wondering what to do next.

Almost exactly the same story as mine then. The relay is clicking often.

Mine is back in the shop, and they said it’s not building the correct pressure, and they suspect the new compressor is faulty. They’re trying with a new one on Monday.

I asked them again about the nitrogen filling, and they said it’s correct but that they’ve stopped doing it. The same has Møller (the absolute main VAG chain in Norway) - stopped doing it. They say it’s not that big of a difference, and that the nitrogen will be switched out with air after a while anyway. But if I manage to find a place that will fill it, I’ll do it.

 

[rgh0]

Many tyre shops offer nitrogen filling for tyres these days so with the right adapter maybe they can fill the system also from their nitrogen bottles?

cheers
Rohan

 

[Veloch]

Many tyre shops offer nitrogen filling for tyres these days so with the right adapter maybe they can fill the system also from their nitrogen bottles?

cheers
Rohan

Atleast in my town only the VW dealer seemed to have the correct adapter.

My problems have continued since getting the nitrous refilled, but I'll write a longer explanation when I have more time.

 

[Veloch]

Atleast in my town only the VW dealer seemed to have the correct adapter.

My problems have continued since getting the nitrous refilled, but I'll write a longer explanation when I have more time.

So, continuing from my previous update, I took the car to the local VW dealer and had them fill the system with nitrogen. Christmas came and the car was working well. After christmas I went to get groceries and I could hear the compressor running again for several times. The next day I again left town to check out some loggingsites around the countryside and had VCDS next to me, looking at the overall system pressure, accumulator pressure and each bag. Starting in the morning, the accumulator had somewhere over 8 bars. By the time I got home, it was around 3 bars.

So I took the car to th dealer again. They ran around with it for 2 hours and found nothing wrong with it. Driving it to the dealer, I could hear the compressor starting atleast 3 times. They told me they couldnt find anything wrong with it. I took it home and checked it the next day. The accumulator pressure was 10.4 bars. I took it to a warm garage for a few nights and the pressure was still 10.4 bars.

This was yesterday and I have been quite confused since. I have no idea if its fine or not. I dont know if its leaking or not or if the pressure drop was due to a frozen sensor or something. What I fear is, its slowly leaking and the compressor is running while its parked to try and fill it every now and then and will eventually break again. Or if it even does that while parked.

 

[SLEI]

My 7P suspension is down and I have bought a repair set for it compressor, valve block, relay. Where this Nitrogen filling area should be, is there a tank with seal between compressed air and pipes connected to air shocks? Air is 78% Nitrogen so basicly everything is Nitrogen filled but air can be very wet depending of weather. I got about 3 months nice airride on my "new" Touareg before real winter kicked in and my fun was over. Vacuum in warm garage would kick out moisture but will it kill valves or seals in struts? Spare parts where quit cheap in ebayde about 300usd and I'm very shure you can't get anything from dealer under 1000. Compressor has quit large plastic box between rubber hose and cylinder head which propaply conteins filter and air drier.

 

[rgh0]

SLEI according to your details your Treg is a 2009 7L which had different air suspension compressor system from the 7P.

The 7L ran on air and had an open system which sucked in air and vented air as the suspension height setting and load went up and down. It both sucked and vented through the air dryer so the dry air coming out regenerated the drier ( mainly) so it worked drying the wet air coming in. This system clearly has problems once the drier effectiveness drops of over time especially in cold wet climates with corrosion inside the system

On the 7P the system was changed to a closed system with an initial nitrogen that only drew in air via the compressor if the system pressure in the reservoir dropped to low. In normal operation the nitrogen initial charge is recirculated by the compressor between the reservoir and the struts as necessary to maintain the required height. i presume their is some sort of warning if the reservoir pressure drops to low such that the system sucks in external air ?

regards
Rohan

 

[SLEI]

I just updated my profile my older Touareg was 7L with steel springs. I have seen many compressor change and repair videos and pictures of parts, compressor area parts look very much same on 7L and 7P, piston ring repair set may even fit to new modell compressor. I think I have some kind of leak, one week parking below freezing sank suspension down and after a month fuse was burned and suspesion didn't rise again.

 

[rgh0]

If you have a leak on a 7P system then the compressor will eventually draw external air in to keep adequate pressure in the reservoir as i understand it. it appears this is not alarmed when it happens and in cold weather you risk water in the wet air that may have been drawn in over an extended period freezing in the system and causing problems.

cheers
Rohan

 

[adidas]

So, continuing from my previous update,

Try this, put the car in extra offroad height and leave it like that. After a few hours check if one corner is sagging.
I have the same problem as you do and found that the rear left is leaking.

 

[Veloch]

Try this, put the car in extra offroad height and leave it like that. After a few hours check if one corner is sagging.
I have the same problem as you do and found that the rear left is leaking.
View attachment 248789

Funny you suggested this just now. I did this last night and I'm going to check out the results later today.

But thanks anyway for the suggestion.

 

[Veloch]

Try this, put the car in extra offroad height and leave it like that. After a few hours check if one corner is sagging.
I have the same problem as you do and found that the rear left is leaking.
View attachment 248789

So I left the car at extra offroad height with jackmode on. I measured it after 24h, and it had risen about 0.5cm, probably due to coming from -10 to +20 degrees. After another 16 hours it hadnt moved at all. So I get in, disable jackmode, lower it to normal height and back it out of the garage. Everything appears to work normally. I close the garage door, get back in and put the car on D and start forward and the compressor starts and runs for 20 or 30 seconds, stops for 5 seconds and starts again.

I cant figure this out.

 

[adidas]

@Veloch , you should let it in extra offroad mode (maximum height) without jackmode. In 15-30 minutes you should see something, if you have a leak.
Also, do you have a VCDS to check these parameters?

 

[Veloch]

@Veloch , you should let it in extra offroad mode (maximum height) without jackmode. In 15-30 minutes you should see something, if you have a leak.
Also, do you have a VCDS to check these parameters?
View attachment 248800

Yeah I have VCDS.

I thought jackmode would close all the valves, eliminating the chance that the car would use pressure from other corners or the accumulator to balance the leaking corner. I'll try without jackmode and see what it does, but do you have a reason to believe it would do something differently without the jackmode?

 

[adidas]

do you have a reason to believe it would do something differently without the jackmode?

No, not really, but when i tested mine i didnt use jackmode and in 15-20 min the rear left was sagging. Also, not sure what exactly jackmode does

 

[TommiT]

I assume you know you need to lock the suspension if you put the car on a wheels-free lift for example.

Lots of workshops won't know this.

 

[TommiT]

And I include VW dealers in lack of knowledge!

 

[Black Grouse]

I assume you know you need to lock the suspension if you put the car on a wheels-free lift for example.

Lots of workshops won't know this.

What happens if you don't? During summer>winter tyre switches that wasn't done but no harm seems to have occurred.

 

[Metalhead_79]

The car will try leveling itself and worst case damage something.

 

[adidas]

@TommiT , i always make sure to put it in jackmode when i lift it

 

[maleksandersen]

I have yet to find a place that (re)fills the system with nitrogen, but haven't given up on it.

A lot has happened in here since my last post, so short story: 2011 7p, 40A suspension fuse blowing out in cold weather, new compressor in with relay and new valve block. Have not been cold enough here for me to see the status, but with the relay clicking in and out all the time my gut feeling says somethings wrong.

Funny how a lot of you mention to measure if it's dropping on on specific side. I did this as well, 12 hours it had dropped 1-2-2-3,5 cm on each wheel. Had it in normal. Still haven't driven it, so gonna check again tomorrow morning. Should it drop anything? If so, is 3,5cm too much?

I have a friend with a 2011 Cayenne, exact same problems as me (and many of you). He drove to a rather special Porche center an hour away, and they put in some special gas to check for leaks. They then again use a electronic gas sniffer to find all leaks.

My strategy at least for now, is to focus on finding any leaks. Then some nitrogen!