Morning all,

Further to my pre-Christmas query about replacing an air strut I have recorded the following and wondered whether anyone could point me in the correct direction towards resolution?

Car is a 2012 Westie with 120k on the clock. Initial symptom was the NSF corner lowering overnight. No codes or dash lights to indicate anything amiss.

I had already resolved to replace the struts and rear bags as a preventative measure as I intend to keep the car for a few years and at the last Indie service my trusted mech said that the front struts were looking a little perished. So the work was done a couple of weeks back over a few hrs at a rent-a-ramp place in accordance with some write-ups on here and a few videos such as Rimmer Bros. BWI front struts and Bilstein rear bags from Island 4 x 4, about £1500 in parts.

Calibration with the GAP IID Tool was completed after all 4 corners were replaced. Unfortunately, the car still drops after a few hours not running. Raising and lowering all seem to work as normal and there is no obvious hissing at off-road height. After running around locally with the GAP tool connected, I confirmed that the compressor only ran up to pressure once and then simply topped up every now and then, figuring that I would not overwork the compressor too much I decided to use it on a 400 mile round trip to Devon over Christmas. Throughout, the car seemed fine and I monitored the suspension live values throughout:

- on start the exhausted gallery pressure is replenished as the compressor runs up to 210-225psi.
- the compressor starts at ambient temp and will generate 210 psi at around 105C when it stops due to working px being achieved.
- Compressor has sometimes run up to 130C when the thermal cut-out operates.
- Compressor was inop most of the time and maintained 50-55C temp throughout most of the 9 hrs driving.
- As soon as compressor cuts out the gallery pressure reduces to around 50psi. It then drops quite quickly to 33 psi where it remains for several hours with the occasional compressor top-up to 50-55psi.
- Height sensor values all maintain around 2.2-25v with the exception of the NSF air strut (the originally suspect leaky strut)which records a 2.9-3.2V, not much extra but a consistently higher value.
- have recalibrated 3 times. Last time it appeared that the calibration didn't work with OSF strut appearing 15mm higher (510mm v 493mm GAP IID guide) than NSF which seems to maintain target value +/-2mm for a while (until engine switched off).
- Rear bags initially hold calibrated height but then drop 10-15mm after driving.

I'm pretty much resolved to rebuilding the compressor, again as a preventative maintenance measure, once I find out which compressor I have but the fact that it generates decent pressure at the gallery indicates it's still in reasonable health. Does the above suggest a reservoir leak or height sensor issue forcing the self-levelling to drop the car overnight? I'd be interested to hear the opinions of those with experience of this system? My only previous attempt at air suspension rectification was a compressor replacement on my old E61 Touring. This seems a little more complex.

Sorry for the war and peace post but I wanted to ensure all the symptoms were made plain.

Happy New Year to all Full Fat L322 owners and fixers.

Pull the relay for the height control and check for any drop overnight. If it's not dropped it's a calibration issue. If it has dropped you have a leak. Are you using the 'guided' calibration method? If so this has a misleading command at the end ( which I can't quite remember) but which can end up with it not saving the calibration. I have checked this by going into custom height adjustment and it will ask to update the new calibration. 2012 TDV8 Vogue (L322)

Thanks for your reply. I used the guided process which suggests the final ‘send’ command stores the calibration but you never get to use any ‘send’ command. I’ll try the manual method if it stops raining and pull the relay this evening.
Will update soonest…

hi did you get this problem sorted in the end ?

following.

I'm no real expert on the suspension but simple process of elimination it's unlikely to be the compressor as it's only 1 corner.

It's going to be a valve, solenoid or pipework or connector by the looks of it, something unique to that corner.

You could do a quick vacuum check @ various jointsalong the pipework to see where its leaking from the point it splits into the 4 corners to the airbag.

As you can't hear it hissing, if possible could you be able to access a smoke generator, they use blue / pink smoke, it's harmless but invaluable to find leaks in airlines.

Other than that it's going to be a case of "half splitting" to gind the fault.

Andy Fuji White / Jet 2012 4.4 TDV8 Westminster

I’ve got a valve block rebuilt for the rear ,hopefully get it fitted this weekend.raise to off road height pull the relay and see it looks the next morning fingers crossed it will be sorted ,if not then air bag or airline like you said

Sorry for slow response all, been out of country for a bit and Rangie suspension has taken a back seat.

I did however recently get it up on a ramp, pull the wheelarch liners and spray liberally with soap and water spray and found no leaks on the new bags nor the lines and block connectors. The height sensors were all inspected at the same time and appeared normal, without any play in the mounts and actuator arms.

So today I recalibrated manually using the GAP IID tool (493mm at front and 485mm at back), pulled the EAS relay from the panel in the boot and after only a couple of hours its' apparent that the car is still dropping on the front left. So I figure I must have a leak somewhere there?

I've also uncovered the compressor (p/n 6H42 3B484-HF so I think that's a Hitachi?) and without the sound deadening fitted I can hear the pump running to lift the car after it's dropped overnight but I can also hear the sound of an exhaust valve somewhere near the compressor activating immediately prior to it running and then immediately after it's stopped. Seems a rather random time to vent the pressure built, just after it has filled the struts, bags and reservoir? Anyone offer any advice as to whether this is normal? Sometimes I can hear a rhythmic mechanical thumping near the compressor but failed to replicate it today.

Would appreciate any further help offered otherwise I'm going to have to bite the bullet and hand it over to my specialist down the road to diagnose.

Hi,

As I said before you don't have a pressure creation issue and that's primarily what any problem codes are going to tell you, you have a pressure retention issue so something is either leaking out or something is allowing depresurisation. I don't think the GAP tool measures pressure differentiation.

It could be a bit of grit stuck in the valve block preventing it from sealing correctly or a leaking joint / split pipe. Are you able to cross the 2 fronts pipes at the valve block ?

Don't drive it this way but if you do that and the fault remains on the same corner then you have a pipework problem, if it doesn't and the fault moves then you've got a valve problem.

Let me know how you get on.

Andy Fuji White / Jet 2012 4.4 TDV8 Westminster

Thought I’d post the resolution to this now it’s fixed after giving up my diagnosis and handing over up the professionals. A local RR specialist diagnosed and fixed the problem in 4 hrs. The black air pipe going from the connector block in the NSF wheel arch to the OSF strut had chafed against the Rangey’s body under the front bonnet scuttle at 2 points, generating pinhole leaks. All sorted now and nice to have her back!