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RichD1

How to diagnose a rear right air suspension problem?

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Came out to the car this morning and found the rear right hand side had collapsed. Unlocked the car and it immediately pumped back up to the correct height. Obviously the pump is running OK and I can hear no hissing noise. The car has not been used much over the last year or so and was last used about two weeks ago.

 

What would cause this deflation? Can a fault code reader detect any problems?

 

I've had the car from new, a 2002 525D Sport Touring and about 10 years ago had the rear right level sensor replaced. Could it be the level sensor again? But the car has just pumped up to it's correct height so the sensor must be working.

 

Where should I start investigating?

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Leaking bag. Lift that corner up, remove wheel and spray some window cleaner or soapy water over bag, you will see bubbles coming from somewhere. There's chance that metal air reservoir is leaking due to rust, but it's not very common issue, so I would check air bag first. It's easy to change as well.

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Thanks Ray, I'll give it a go and report back.

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Just checked after about 5 hours and its dropped about 25mm. So will do the soapy water test but if that's Ok what next? I can check the pipes at the top of the air bags for leaks but I guess the other area would be the control valves or the reservoir. Where are they located?

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43 minutes ago, RichD1 said:

Just checked after about 5 hours and its dropped about 25mm. So will do the soapy water test but if that's Ok what next? I can check the pipes at the top of the air bags for leaks but I guess the other area would be the control valves or the reservoir. Where are they located?

Don't think further than soapy water test for now. I'm almost hundred percent sure, it will be air bag, especially if car is still on original ones. They are 20 years old, give or take, so rubber is full of micro cracks.

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As Ray said; check the bag carefully and more than likely look to replace it.

 

Personally I'd replace both as it'd be sods law that the other fails not long after...

 

Arnott would be my choice; but Aerosus are also well thought of

 

I wouldn't veer away from them 2 makes and certainly wouldn't consider any eBay special air bag; but it's up to you; your car/your £££ @RichD1

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Ok, just got car jacked upo and wheel off. Brushed dirt off and  liberally sprayed around with some gas leak detector stuff and I could see no bubbles!!

 

Wondering if the bag needs to be under pressure to show up leaks? It takes about 24 hours to go down so is the leak is so small that under no load it doesn't leak.  

 

Had the air pump plate off and sprayed the couple of joints right back to the top of the air bag and still no sign of bubbles. Could see no signs of damage on the small air pipes either. 

Edited by RichD1

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Air spring being under load will help detect leak due to increased pressure in system. 

 

There's a possibility that reservoir tanks are leaking, but it's not very common and it's quite hard to check for leaks, because you can't see or reach top side of them. If you are still on original bags, I would inspect them carefully, spray that gas leak detector around and leave it for 15-20 minutes, then come back and have another careful look, very slow leak might not be noticeable right away, it takes a bit of time until you start to see bubbles around that area.

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1 hour ago, Ray112 said:

Air spring being under load will help detect leak due to increased pressure in system. 

 

There's a possibility that reservoir tanks are leaking, but it's not very common and it's quite hard to check for leaks, because you can't see or reach top side of them. If you are still on original bags, I would inspect them carefully, spray that gas leak detector around and leave it for 15-20 minutes, then come back and have another careful look, very slow leak might not be noticeable right away, it takes a bit of time until you start to see bubbles around that area.

 

Agree with this; but check connections at the compressor end too; peace of mind etc

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My opinion is that if you are on original air bags change them and both of  them. Highly likely it is one of the bags though not definite.  Even so they are 20 years old, safety related and made of rubber.  Most people i think would not want 20 year old tyres on a car, the rubber degrades over time.  I have had two arnotts on my car for the last 3 years since one of the originals blew out on the A1 at 60mph.  Not fun at all.  If you've a slow leak it could develop into something worse.

I did a lot of research an personally would not use aerosus (only my view though).  Arnott are reckoned by many to be better than OEM and OEM are expensive anyway.  Note that arnott have different clips supplied with them that you must use and the same bags fit both SE and sport tourings.

Edited by Dbcrd

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2 hours ago, Dbcrd said:

My opinion is that if you are on original air bags change them and both of  them. Highly likely it is one of the bags though not definite.  Even so they are 20 years old, safety related and made of rubber.  Most people i think would not want 20 year old tyres on a car, the rubber degrades over time.  I have had two arnotts on my car for the last 3 years since one of the originals blew out on the A1 at 60mph.  Not fun at all.  If you've a slow leak it could develop into something worse.

I did a lot of research an personally would not use aerosus (only my view though).  Arnott are reckoned by many to be better than OEM and OEM are expensive anyway.  Note that arnott have different clips supplied with them that you must use and the same bags fit both SE and sport tourings.

 

^^ This also :)

 

I'm changing mine out to Arnott; my current SLS bags are original from Nov 2002! They may have started their life in Japan; but they, IMO, need to be replaced and they'll be the last part of the suspension on my touring that's original.

 

They're £235 for both via Autodoc; or £270 via a UK reseller; thinking I'd rather pay that bit more and know I'll get them rather than wondering when they may land :lol: 

 

** Edit: Ordered from the UK reseller 

Edited by d_a_n1979

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Had a chat with my local BM Indy and he echoes all of the above. I've checked all the small pipe fittings back to the compressor and can't find any leaks and as it pumps up and levels its not a sensor. He also agrees that he'd never seen a reservoir leak in his 30 years of working on BM air suspension.

 

So i've ordered a set of Bilsteins as my son gets good discounts on their products, £240 a pair. Was going to replace the rear shocks with Bilstein B6s but found a rust holes in the spare wheel well. This with the normal wheelarch rust means it might have to go next year.

 

I've had it from new and it's been a great car with almost 180K on the clock, but it wants quite a bit of welding and tidying up and then some respray so maybe nows the time for it to go.

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Is it true that once the air bags have been installed then it needs to be set up using the BM OBD reader/coder?

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18 minutes ago, RichD1 said:

Is it true that once the air bags have been installed then it needs to be set up using the BM OBD reader/coder?

 

No, battery off

 

Old bags disconnected (carefully) reinstall, battery connected, engine on and let them reinflate.

 

The sensors will know where the car height was last time around and it'll set it back to that IIRC

 

I think that's right...

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And be careful about plastic clips on top of bag if doing job yourself. You need to push tabs on clip together so split on other side opens wider and connector can be pulled up. There and fair few videos on YouTube about how to do it, actually really easy. I would say coil sprin makes a lot more more hassle to replace than those air springs.

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14 hours ago, d_a_n1979 said:

 

^^ This also :)

 

I'm changing mine out to Arnott; my current SLS bags are original from Nov 2002! They may have started their life in Japan; but they, IMO, need to be replaced and they'll be the last part of the suspension on my touring that's original.

 

They're £235 for both via Autodoc; or £270 via a UK reseller; thinking I'd rather pay that bit more and know I'll get them rather than wondering when they may land :lol: 

 

** Edit: Ordered from the UK reseller 

Got mine from HIDs direct.  Price seems to have gone up a fair bit.  https://www.hids-direct.co.uk/arnott-rear-right-air-spring-97-03-bmw-5-series-e39-wagon-w-rear-air-leveling/

 

Note that Arnotts have a different pipe retaining clip.  It is a sort of bayonett fixing that needs to be installed the right way around - as i found out when installing the wrong way round at first and blowing the pipe off.  Keep your old clips as they are unavailable new on their own just in case you ever want to go back to OEM (only available with whole reservoir assembly i think).  There is a paper gasket between the bag and the mounting they say you should reuse.  Not sure what it does or what value it has but that is what i did.

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1 hour ago, Dbcrd said:

Got mine from HIDs direct.  Price seems to have gone up a fair bit.  https://www.hids-direct.co.uk/arnott-rear-right-air-spring-97-03-bmw-5-series-e39-wagon-w-rear-air-leveling/

 

Note that Arnotts have a different pipe retaining clip.  It is a sort of bayonett fixing that needs to be installed the right way around - as i found out when installing the wrong way round at first and blowing the pipe off.  Keep your old clips as they are unavailable new on their own just in case you ever want to go back to OEM (only available with whole reservoir assembly i think).  There is a paper gasket between the bag and the mounting they say you should reuse.  Not sure what it does or what value it has but that is what i did.

 

Cheers for that

 

Autodoc had them at c£120 per corner IIRC; but then you've the 'wondering when they'll ever land' worries going on etc...

 

It took them 3 weeks to deliver my rear ATE discs & pads! No tracking until the day they landed in the UK and Parcelforce emailed me with an update... :roll: 

 

I'll give them a good look over once they land and suss out this new clip etc

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Would you believe it, went out to the car this morning to pump it up as usual and it hadn't gone down overnight. The jacking up and down and fully extending the bag must have moved the air bag a tad so as to seal the hole.

 

Still going to change them when the Bilsteins are delivered.

 

 

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7 minutes ago, RichD1 said:

Would you believe it, went out to the car this morning to pump it up as usual and it hadn't gone down overnight. The jacking up and down and fully extending the bag must have moved the air bag a tad so as to seal the hole.

 

Still going to change them when the Bilsteins are delivered.

 

 

Good idea.  That phenomenon has been reported before.  If there is a pinhole it could get worse.

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Mine was a long split that came all of a sudden and lost all the air at once and dropped the suspension while i was driving on a busy dual carriageway.  No dropping over night or any of that.

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