AIR SUSPENSION 4.8iS - ANOTHER ONE - VIEWS PLEASE

gobiman · Post by **gobiman** » Mon Sep 24, 2012 10:32 am

I have a problem with my air suspension and having trawled the extensive and very helpful posts on the issue would be grateful for any views hints on my initial diagnosis from those who've had similar problems.
The car is a 2004 4.8iS. I left it for 4 weeks over the summer parked on a kerb. On my return I noticed that the front was down (looked like a dragster). However, once I'd started up it raised itself within a minute or so to the normal height and was normal to drive. No error messages on the dash at any point. Drove 300 miles or so.
It was then fine until it was left for about a week and the same thing happened. I actually drove off straight away and the ride was rock hard until a couple of minutes in, when it had readjusted.
It has happened one more time overnight but interestingly had raised itself in the 3-4 minutes between unlocking and start up.
My best guess is that there is a leak in the front somewhere - maybe one or both of the airbags. It is not sufficient to cause an error message. The compressor and the sensors are clearly working. I'm assuming that if left unattended it will simply get worse over time and finally pack-up.
It has its annual service at my trusted indy in a month or so and I am intending to get it seen to then.
Any views or thoughts on this (particularly if my diagnosis is flawed) would be very welcome.
Thanks in advance.

CondorX5 · Post by **CondorX5** » Mon Sep 24, 2012 11:12 am

A bit like the Range Rover p38 whose heritage ( and air suspension woes) the 4.8 shares. The air bags do become brittle with age and develop slow leaks in cracks which will mean the compressor has to work constantly to keep the air pressure up, so will wear out sooner or later ( big bucks to replace bags plus compressor). I had a P38 Rangey and didn't have issues with the air suspension after changing air bags, I also had a manually inflatable system fitted as an extra so I could top up air pressure if it ever dropped to the bump stops (the worst ride ever, on the bump stops! ) but never needed it again in the 7 years I owned the Rangey.

I would say have the air bags looked at and change at least the fronts, if not all four. It will save replacing the compressor later!

Sanj · Post by **Sanj** » Mon Sep 24, 2012 11:42 am

Have a look herefor potential fix and then herefor spare parts if you decide to stay OEM.

Raj has only just posted bits for sale and if you work out what is wrong with yours, you may get lucky with his bits for sale...

gobiman · Post by **gobiman** » Mon Sep 24, 2012 12:16 pm

Thanks for the replies - some thinking to be done!

Raj · Post by **Raj** » Mon Sep 24, 2012 1:20 pm

As Sanj has posted I've binned all mine off. I don't think it the pump from what you have described (but if not resovled soon'ish it could knock the pump out too due to overworking. It does sound like it is either the front airbags are leaking (but the fact it's both seems a bit coincidental), which would possibly lead me towards either the valve block (more likely) or the accumulator.

I do have the components removed from mine still sat in the garage. I've got a complete front nearside shock/airbag, both rear airbags, the accumulator and valve block. So let me know if you need any of them (accumulator and valve block are both about 18 months old from BMW).

gobiman · Post by **gobiman** » Mon Sep 24, 2012 5:40 pm

Raj,
Thanks for that - pm ed.

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