L320 RRS air suspension - a question of leaks

[Jordie Barretts sock]

My Sport has developed it's first suspension issue, which isn't bad after 97k and 17 years.

Driving along it will randomly flash up 'suspension fault' then a moment or two later it will disable all special functions for the suspension and the hill descent control. Stopping and switching off and on will reset this, only for it to reappear within a mile or so.

I noticed the compressor for the suspension seems to be running all the time. My diagnosis was it's likely a leak in the airsprings.

The question is, replace them all or only the leaky one(s)? In view of one leaking, the others being the same age, I'm guessing it makes sense to do all four, as sooner or later they'll all start to leak.

[shirt]

best to diagnose the leak source first, IME valve blocks go before bags.

pull the suspension fuse to prevent it from self levelling and leave it for a bit. if one corner is down then its the strut. if one axle is down then its the valve block for that axle [or both struts, but unlikely that 2+ fail at once]. if all 4 are down then the centre valve block or the compressor itself.

[Jordie Barretts sock]

Excellent. I'll do that first.

If it is an airspring, is it OK to replace them on their own?

[Jordie Barretts sock]

Front is down more than the rear. But front nearside seems to be down more than the offside by about an inch.

[dingg]

Just change the front pair, rears last for ages.
Change full struts not just bags ime.

[Jordie Barretts sock]

Yeah, was planning on full leg, not just the bag.

Thanks!

Edited by Jordie Barretts sock on Monday 28th August 13:22

[shirt]

Jordie Barretts sock said:

Front is down more than the rear. But front nearside seems to be down more than the offside by about an inch.

best way to tell is put a bit of taut masking tape between each arch and wheel. once you have your main suspect repeat but with some washing up liquid/water. changing a strut is a bit of a PITA so i'd want to be sure.

[agent006]

Airbags always used to be something that should be considered a 10 year consumable on a properly maintained P38, so unless the design is fundamentally different now, you're doing very well to have gone so long on the originals.