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Air suspension issues

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It had the usual slow leak making the N/S slowly drop, I had it on the to do list till the accumulator burst dropping the N/S to the ground in a instant. So I fitted a new one from BMW, but as suspected the airbag its self failed soon after. I got a new one from Aerosus as they were less than half the price of genuine ones but that failed within an hour of fitting, there was a fault in the steal pressing on the top but they changed it without fuss (apart from me having to cover the cost of post to Germany). The replacement has been fine since then. It had some heavy use for a good few hundred miles with no more sagging, which was nice. The N/S has continued to be fine ever since.


I thought I really should do the O/S as it looked as bad as the N/S had even though it wasn't causing any issues, however when I fitted the new genuine accumulator & Aerosus bag the O/S stared leaking, slowly going down over a few days if not being used, just as the N/S had right at the start of the issue.


I had cheated slightly by leaving the new accumulators under the floor in the boot after spending some time getting the N/S one out I wasn't sure I'd get the new one in with out bending the hard plastic pipe & I could see there was no way the O/S was going in with out at least removing the exhaust. Because of that the good O/S accumulator was still on the car so it was very easy to just plug that on to the new airbag, but unsurprisingly it still had the slow leak. So it seemed it must have been the new airbag at fault again, so I refitted the old bag back on. So it now had all the parts it had before on the O/S when it didn't leak, but it still slowly leaks!


Is there anywhere else further upstream it could be leaking from? I've tried soapy water round the fittings on the top of the bag where I had to re-attach feed pipe of but there are no bubbles. So I'm wandering if there are some valves that maybe let air out again after it's been pumped up for a heavy load that could be leaking?

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Under the spare wheel is a black dome, unbolt from the floor then split it, inside is the compressor & solenoid valves. Likely one of those leaking. Operate the suspension and when the compressor stops you should hear one passing. 

It could be plunger or possibly the o ring where the solenoid seats. Of top of me head it's 25-30mm x 2mm?


Hopes it's helpfull




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