single rear wheel suspension Issue- hissing and low

[wakevortex]

Hi all-  RX330 2004 , Spain.. 

Recently we have heard a small hissing sound coming from rear left wheel after getting out of the car ..and its visibly lower .
If I then RAISE the whole car using the dash button  to HIGH- all wheels raise and stay there (with no hissing)
I then go for a drive  drive..all is well.. (the height indicators on dash show MED)  until I stop/switch off , then the hiss again from left rear, and it goes back down (only when stopped/switched off) 
This is repeatable ..
any ideas what exactly this could be? .. my local garage (NOT lexus dealer)  is going down the road of a whole replacement suspension strut for  that wheel (which is apparently REALLY hard to find- Im in Spain by the way ) 
Is there a halfway house fix it could be, or is that the only course of action 

Thanks in advance. !

[wakevortex]

It seems more random than I first thought..it stayed normal height for 3 days while parked up, then went back down after one short trip .. 

Could there be something like a faulty sensor (is one involved) but then why would  it hiss like there is a leak.. ?

perplexed by this as the garage dont  seem exactly sure WHY they want to change the whole strut !

[Herbie]

Take the opportunity to change from air to coils - you can get a whole brand new set of coils for not much more than one air strut.

[wakevortex]

10 hours ago, Herbie said:

take the opportunity to change from air to coils -

Yes I had read about that, but currently not even sure I need a new strut..thats the problem !
Im surprised it would cost not much more to go to coils. ..surely not including Labour ? 

[Herbie]

3 hours ago, wakevortex said:

Im surprised it would cost not much more to go to coils. ..surely not including Labour ?

No, I'm only talking of the cost of the parts. I believe it's about £600 or just over for one brand new air strut, but only about £1,000 or slightly more for a brand new set of four coil struts.

[wakevortex]

Just now, Herbie said:

£1,000 or slightly more for a brand new set of four coil struts

Wow..thats really very reasonable ! ...Im guessing its not a quick job to replace all 4 though in terms of labour  ..  
Any ideas about this particular issue... I hate just replacing a part without knowing whether it actually NEEDS to be done or it can be fixed by another route.. 
maybe its too much hassle to fault find it on the Lexus? 

[Herbie]

Sorry Bill, I honestly don't know as it's a job I've never had to do. I only know what I've picked up in these forums.

[wakevortex]

Just now, Herbie said:

honestly don't know as it's a job I've never had to do

No problem Herbie ..I appreciate your input..hopefully someone will have had this issue before-  fingers crossed. !

[Tomtit]

I had this problem on my LS430. One of the rear corners kept dropping. The cost of one new air strut would have equalled the market value of the car. There was also the possibility of another strut failing. It made financial sense to fit conventional coil springs and dampers all round. I bought all the parts for £1000 and fitted them myself. My suspension will now last the lifetime of the car.

[wakevortex]

12 minutes ago, Tomtit said:

t made financial sense to fit conventional coil springs and dampers all round. I

Thats really interesting ..thanks for that insight ..Im waiting to see if they can source a second hand or reconditioned one ,and if not the coil spring route may may well be an option to look at...cheers 

[Tomtit]

I think I have read somewhere that there is little difference in ride quality between air suspension and coil springs and dampers on a RX300. It may be the same on a RX330.

My wife's RX300 (on air suspension) feels crude compared to my LS430 on springs and dampers. 

[wakevortex]

9 hours ago, Tomtit said:

I think I have read somewhere that there is little difference in ride quality between air suspension and coil springs and dampers on a RX300. It may be the same on a RX330.

My wife's RX300 (on air suspension) feels crude compared to my LS430 on springs and dampers. 

Im still not convinced our problem requires a new strut...it now seems random..with the suspension rear left behaving completely normally for 2 or 3 journeys, and then for no reason just dropping when car is parked up.. (not REALLY low by the way, just to lower than normal )  
Does ANYONE know if this could be a sensor problem of some sort? 

[steve2006]

The sensors can suffer from water ingress not helped by where they are unavoidably positioned.

There have been reports of repair success by removing the sensor cover and cleaning the electrical tracks within it.

Given that the suspension is not sinking overnight and rising when switched to high I would concur it is more likely to be the sensor than the strut, the hissing noise is just the exhaust port opening to lower the car, the same will happen if you place the suspension into high then back to normal on all the struts.

One thing to check is the link bar from the sensor to the suspension, these consist of an aluminium bar with a swivel joint on each end.They have a tendency to corrode and then break off at the joint.

A quick look on eBay shows new sensors for around £100.00, as for the quality I don’t know but maybe worth it at that price compared to OEM prices.

https://tinyurl.com/mukbt5w3

 

[wakevortex]

4 hours ago, steve2006 said:

I would concur it is more likely to be the sensor than the strut,

Steve..thank you - this is great info and fits with my own thinking given the symptoms.. 
Will pass this on to my garage and see what they think...
its certainly worth an investigation considering the potential cost - and thanks for the link  - that same seller is doing some pretty good prices on the whole suspension strut !(if I can get it from the Uk without post Brexit customs nightmares)

https://www.ebay.co.uk/itm/174909377163?fits=Car+Make%3ALexus&hash=item28b9694a8b:g:NLgAAOSw6Idh9LCx&amdata=enc%3AAQAIAAAA8CZr%2F7Bf5BvoUA5EuAcZ5ogCYIhnDhzfKsCLFaNHCYwfVZNPTZeZKZCAvIwUXtt6A9LcmX83DKEsyUYnUL2Np%2Fgf3xmYRa5XHKfpu9ALbTgmSxn%2BDLff6PwtG6w5r3pPs5QTtJ00IHEUKgcRy65JWoGekoIAN3CAteZR0ODwyv6kN1BdEcTqEsIeOFzZ5fw9EPhAxiuI6Wa2BTRg5xMMFPedyeX%2B2bTYGziPWfmjlhjyvwHm03%2BelQWTdSfNo6BJtSqVgNy3drwin2m7VWy49y8zv0oQ6Qk5H70d1ay40WUxyR2SHuPdngFMaP1qPGECAg%3D%3D|tkp%3ABk9SR_6cmrGEYg

all much appreciated. !