First air suspension issue

[harvmiester17]

Hi, I've just joined here so I hope you don't mind me buting inn. I may be able to she'd some light on the problems you are facing. I own a Cayenne, Touareg and Q7 specialists in Newcastle and I have come across these codes many times and they are 90% of the time down to the compressor. It's made by Wabco and is used in nearly all the luxury cars produced in Europe and its biggest flaw is the piston ring in the compressor. Normally the fault appears after sitting over night, a short time after you start driving a fault will show on the dash as the compressor tries to refill the system.

The piston ring wears over time and allows blow by, the poor motor is working so hard to fill the system it overheats and shuts down. The old piston ring is made of fibreglass but the new one is a carbon composite so doesn't wear as quickly.

First thing you need to do is stop running tests on your system until you have repaired the compressor or you will be buying a new one, the motor will only put up with so many overheats and simply stops altogether. When you have removed the compressor housing from the car you will need to take your time with removing the bolts as they are held in with Locktite! If you round the bolt, Irwin tools do extractors which lock on to the damaged head as you turn it. Carefully heating the bolt also helps to burn away the Locktite. Once the bolts are out it's a simple job to overhaul the pump. Clean the cylinder wall with brake cleaner. Do not use any lubricant (the pump is dry running), replace the piston ring making sure the taper is in the same direction as the old one, replace the rubber seal and reassemble the housing.

If done properly this repair will last for years and solve a lot of problems on the air suspension.

Hope this helps.

H

[gninnam]

Thanks for your reply.
My error is slightly different though.
Depending on the ambient temperature depends on when the light comes on!
If very cold, it can take a good 15 to 20 minutes before the light is on.
If warm (ish), then 5 to 10 minutes.
So - it does sound like the pump is working hard, but this could be down to a leak?

Seeming that the cost of the piston ring and bolt extractor are low, it would be foolish of me not to do the upgrade but I will still check for leaks.

Many thanks for your post

[harvmiester17]

Yes your right it could be a leak, it could also be that the ambient temperature affects how long it takes for the pump to overheat. Pump kit is roughly £20 on eBay and bolt grip set is about the same.
Hope you get it sorted

[M-A8]

Originally Posted by harvmiester17

Hi, I've just joined here so I hope you don't mind me buting inn. I may be able to she'd some light on the problems you are facing. I own a Cayenne, Touareg and Q7 specialists in Newcastle and I have come across these codes many times and they are 90% of the time down to the compressor. It's made by Wabco and is used in nearly all the luxury cars produced in Europe and its biggest flaw is the piston ring in the compressor. Normally the fault appears after sitting over night, a short time after you start driving a fault will show on the dash as the compressor tries to refill the system.

The piston ring wears over time and allows blow by, the poor motor is working so hard to fill the system it overheats and shuts down. The old piston ring is made of fibreglass but the new one is a carbon composite so doesn't wear as quickly.

First thing you need to do is stop running tests on your system until you have repaired the compressor or you will be buying a new one, the motor will only put up with so many overheats and simply stops altogether. When you have removed the compressor housing from the car you will need to take your time with removing the bolts as they are held in with Locktite! If you round the bolt, Irwin tools do extractors which lock on to the damaged head as you turn it. Carefully heating the bolt also helps to burn away the Locktite. Once the bolts are out it's a simple job to overhaul the pump. Clean the cylinder wall with brake cleaner. Do not use any lubricant (the pump is dry running), replace the piston ring making sure the taper is in the same direction as the old one, replace the rubber seal and reassemble the housing.

If done properly this repair will last for years and solve a lot of problems on the air suspension.

Hope this helps.

H

Very very interesting
Thanks for the info, valuable lesson for sure

Very quick question, do you know is compressor could be related to VCDS lowering problems as well?? I can go -15mm at the front and -10mm at the rear, but below that it wont let me anymore, it errors me when calibrating at the end, usually after entering values for the front axle and switching to rear axle??

I will be doing this rebuild anyway next time I've got the bumper off

[harvmiester17]

When you alter the height settings front or rear the system will automatically do a self test, if any faults are detected it will through up a fault code. If you aren't experiencing any other fault with the system then it may not be the compressor. I did however come across a similar fault on a Range Rover and it turned out to be a front height corrector (sensor on the suspension arm) sending an implausible signal to the control module when it got to a specific height. The sensor didn't show at fault when I read the faults, only a vague random signal fault. What code or codes are you getting?

[M-A8]

This is the code I'm getting from time to time, well, I think it there every time I do scan which is every few months

1 Fault Found:
01772 - Signal from Level Control Pressure Sensor (G291)
008 - Implausible Signal - Intermittent

Height corrector would make sense to be honest.
Do you know how much they are each??

Cheers

[gninnam]

Took the lining out of the rear offside arch to have a look and the accumulator doesn't look to good to me - could this be the issue?




I think at the weekend I will take the liners off all wheel arches and have a play with the suspension to see if I can find a definitive leak.....

[Delboy]

should be easily diagnosed with a spray bottle with soapy water

[M-A8]

Was going to say same thing, while arch was off all you could spray some soapy water and if its leaking you would know it straight away.

[gninnam]

That's the plan