How do I deflate my suspension safely??

[SCUTHY2002]

My 2003 XJR has developed a fault with the air suspension compressor. The vent valve has jammed shut and as a result the suspension is jacked up like its on viagra!!
My problem is how do I safely de-pressurise the system so that I can remove the compressor for repair/replacement??
Any advice please? Steve.

[J44EAG]

I`ve just spoken to Ian Kelsall at XJK on your behalf about this problem.

Apparently a stuck vent valve is something Ian has never seen. He thought it unlikely there was an issue with the valve block on the accumulator which is located below the spare wheel. Ian advised checking all level sensors on the upper wishbone arms as a starting point particularly for security and completeness around the knuckle joint and mountings for the sensors attached to the lever arms. Some cars will have four lever sensors whilst later cars only have one at the front. A level sensor if misplaced could send a false signal which could cause the suspension to over inflate.

The recommended procedure for depressurizing the system would be via the SDD dealer level diagnostic tool. That said (and I have indeed done this myself) Ian said that with the ignition switched off it is possible to deflate the suspension by very carefully releasing air from the top of the damper mounting. A nut screws to the top of the damper with a black air pipe running through it. Take extreme car to control the air pipe and nut as obviously the system is under pressure.

Should yu not be able to fix the issue yourself, then a trip to a local independent Jaguar specialist is probably the safest option.

Please let us know how you get over this issue.

Hope this helps.

Mike

[oldtimer]

Mike,
Just out of interest what sort of pressure are we talking about ?

[ptjs1]

I think the reservoir holds at about 180psi and the system operates at about 55psi. So, small pipe and 55psi can be quite uncomfortable.

Paul

[J44EAG]

Astute posts, so take extreme care if you don`t use the recommended method via SDD or IDS gear. Your car and your risk, gents.

Mike

[SCUTHY2002]

Thanks for your help and advice guys. It was actually at XJK 2 weeks ago. It was for a general check and engine service. Ian noticed that a safety recall from 2009 had not been done on the brake pipes so it is currently with Sratstone for free replacment of the front to rear pipe.
I will take a look to see if its a simple thing like a dislodged sensor. I have a brand new Wabco compressor in the shed which I wanted to fit anyway so if I can safely release the pressure I will get that swapped and refurb the old one as a spare.
I will post the outcome.
Steve.

[SCUTHY2002]

Ok, so I managed to deflate the suspension and fit the new compressor. started the car and nothing happens. Drove it around the block a couple of times ( great low rider!) and no attempt to inflate but no codes thrown just vehicle too low message. Checked the fuses and relay and they are all ok. Any ideas considering the original problem was over inflation? If all else fails it will be a 9 mile embarrasing drive to XJK. Steve.

[J44EAG]

Try a battery hard dump battery disconnection for half an hour. with luck that should clear any stray fault codes that may be fouling things up.

I suspect the electronics have become confused after your jack up scenario. These things happen. Give it a try. It is worth noting that after a suspension tear down, I had to wait ten minutes for the air suspension to sort itself out before normal ride height resumed.

Mike

[SCUTHY2002]

Hi Mike. Thanks for that. I didn't mention it but I have tried both a short and an extended battery disconnect to no avail. I have left the car running for 20 minutes as well as the drive around the block but it will just not kick in for some reason. at a bit of a loss as to what to do next

[J44EAG]

Suggest a call to ian or gavin at XJK.

Mike

[ptjs1]

Just a suggestion: How about jacking up one end to get the wheels and sensors to extend, then running the engine and seeing if that fools the system into starting up and maintaining the height?

Paul

[SCUTHY2002]

Thanks Paul. Tried that last night and no luck.

[J44EAG]

I wonder if the module or connection might have a corrosion hot spot. Worth excerpting the connecting plug and socket?

Do you have a code reader to hand? Electronic diagnosis is probably the next move.

Mike

[SCUTHY2002]

Hi Mike
Had a long chat with Ian at XJK. Going to check the height sensors are all ok next and I have also acquired a spare module and solenoid block so this thing will not beat me!! Yes I have a simple OBD reader and there are no codes showing at the moment. She is still stuck on the drive looking like a Gas Monkey Lowrider but weather permitting I will get stuck in again tonight.
Steve.

[SCUTHY2002]

OMG!! Did not expect snow and hail to stop me working on the x350 last night!! Crazy climate!