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I have a 2005 XJ350 4.2 LWB that has been suffering from a leaking air suspension for a number of years. The car has been little used and am just restoring it in several ares at the moment leaving the Air Supension until last.
Diagnosing the root of the air suspension problem had so far confounded my mechanic so I wondered if anyone can point us in the right direction. So here goes with as accurate description of the symptoms as I can manage
When the car is parked up and left for a couple of hours there is no apparent drop in the suspension, however a period of about six hours the front of the car will gradually lower itself and possibly slightly more quickly on the front offside.
Starting the car will result in the car apparently doing nothing for a minute and the gradually returning to full height over another minute or so. Once up to height , the car drives normally but an 'Air Suspension Fault' warning light will sometimes come on and sometimes not.
If the car is left without starting for more than 3 - 4 days the suspension will gradually settle down all round. Then when starting the car it takes longer for the suspension to come up maybe 5 - 10 minutes before you can see it start to come up again.
If the car has been left without being started for more than a couple of weeks then even starting it won't see the suspension coming up even after it has been left running for 20 minutes. Driving the care carefully (and ignoring the 'Vehicle too Low' Warning Message) has usually resulted in the car suspension coming up.
On a couple of occasions the car was not started for several months. Starting the car, leaving it running for twenty minutes and then driving it did not produce any movement in the suspension. However on one occasion when this happened I put the front of the car on some simple carp ramps to investigate underneath and almost immediately after doing this the suspension came up. Having discovered this, if the car was ever like this and not coming up I put it on the ramps and it comes up more or less straight away.
Now I start the car every morning and in a couple of minutes the the car is up but by the evening it is down at the front again.
We ave checked all the obvious places with soapy water and there is apparently no sign of leak.
If anyone has any ideas on where we should start looking next or what to change first I would be extremely grateful.
Many Thanks Henry
This has been discussed on this forum before. The air springs are leaking, probably the front ones. The air compressor will try to pump them back up but will time out after a few minutes. You will likely need to replace both front air springs and replacing the overworked compressor would not be a bad idea. Some owners have opted to replace the air spring with coil spring replacements.
Thanks Don, have been investigating further and seems to be the first option would be to replace the front units. I have found new ones in Germany made by a company Aerosus for just over €700 euros for the pair. I wondered if there is any experience of these? An attractive option compared with jaguar at around 1200 each and Bilstein B4 best par of 2k for a pair. https://aerosus.net/jaguar/xj-series...?pf=1&dontKnow[]=p_model_edition
Thanks for all the great wealth of knowledge you have shared on the subject
Thanks Don, have been investigating further and seems to be the first option would be to replace the front units. I have found new ones in Germany made by a company Aerosus for just over €700 euros for the pair. I wondered if there is any experience of these? An attractive option compared with jaguar at around 1200 each and Bilstein B4 best par of 2k for a pair. https://aerosus.net/jaguar/xj-series...?pf=1&dontKnow=p_model_edition
Thanks for all the great wealth of knowledge you have shared on the subject
Hi Henry,
Before you commit, contact Aerosus to ask if their new air spring/shock absorber units will preserve your CATS functionality. Most of the aftermarket units do not. If the Aerosus units do not have adaptive damping capability, or a resistor or inductor to connect to your harnesses, you will have a constant CATS FAULT warning on the instrument cluster.
Looking at their website, it appears they may sell replacement air springs that could be fitted to your existing shocks:
Thanks again Don. Will get onto them tomorrow and ask the question regarding the CATS and the air new air spring shock absorber
If it isn't and the air springs are suitable, would it matter if the shocks remained the old ones?
Thanks again
If your old shocks are still behaving well, you might be happy just exchanging the air springs. Ask Aerosus if they can supply instructions for exchanging the air springs so you'll know what you would be getting into.
Thanks Don , The shocks seem fine. I have just sent the question to them. My car has the Sport struts these would be suitable for them? And changing to these would not affect the CATs System?
Sorry for the thick questions but haven't dealt with air suspension before
Thanks Don , The shocks seem fine. I have just sent the question to them. My car has the Sport struts these would be suitable for them? And changing to these would not affect the CATs System?
Ask Aerosus, but I suspect the air springs will fit your sport struts. The CATS system works with the shock absorbers, not the air springs, so if you can just change air springs, your CATS system should continue to function.
Recently, I've experienced some or all of the aforementioned symptoms to my air ride system on my '04 XJR. I have a little over 163K miles on the clock. My issue began with over inflating rear shocks. The rear end of my XJR was very high and the ride was extremely bouncy. I immediately went to the trunk, under the spare tire, and released air at air suspension valve block. Initially I could let the air out and force the compressor to inflate the reservoir and ride comfortably for awhile before the rear end over inflated again. I changed the valve block, air compressor, right front shock, to no avail. Finally I got smart, bought a scanner for my old Jag from Icarsoft, and discovered the right ride rear height sensor was bad. I found the two rear sensors on eBay and installed them this weekend, one on each side. It was a good thing i bought them both. The bad right rear height sensor was actually on the drivers side. All good!
Good to hear you are sorted. I'm still trying to isolate the problem and have just acquired a second hand front sprint to try isolate the problem before going to the expense of new springs / compressor etc stc. Interested by your Icarsoft scanner. Which model is it? That would help me a lot.
Asked the question of Aerosus and they asked me for the original part number of the strut / springs. I sent them the photo (attached) and gave them the VIN No and model / year of the car but they said they couldn't tell if their springs would work with these struts without the original part numbers. Seems a bit strange as that is what they do and they are made for this car. Have acquired a working second hand strut and plan to change the most likely candidate for leak which is the front off-side. before going to the expense of investing in new ones.
Asked the question of Aerosus and they asked me for the original part number of the strut / springs.
Hi Henry,
The number on that label does not look like the Jaguar part number. You can find the part numbers for your car at jaguarlandroverclassicparts.com. I believe your supercharged X350 LWB probably came with the Sport air spring/damper units, but I could be wrong and they may have been the Comfort units. You can determine which yours are because the Sport units have a round red "dot" label on the air spring cover and the Comfort units have round green "dot" labels.
Thanks Don, They are definitely sports units as have the red dot. Finally, more as a diagnostic exercise acquired a second hand unit and changed the front offside unit yesterday the problem seems to be 80% cured with the offside not dropping at all this morning and the nearside front dropping a small amount (about 1cm) which would seem to indicate it needs the nearside changed as well. So am planning to replace this next week. Once problem is identified then I will look at a more lasting solution. I'll let you know how we get on.
Since the ECATS adaptive damping system adjusts the valving in the shock absorbers, which are filled with nitrogen and oil, there is no air involved in "CATS ride compensation."
Air is only used to fill and level the air spring bladders, and "how much" (by weight? mass? volume?) depends on ambient temperatures and barometric pressures. What matters is that the proper pressures are developed and maintained in the reservoir and individual air springs.
The general understanding of the word "leak" is an undesired and unintentional loss from a container of a substance such as a gas, fluid, powder, etc. So in that sense, the air suspension is not designed to "leak." The system is designed so the ASM periodically "wakes up," compares the signals from the ride height sensors, and if necessary, intentionally opens the exhaust valve and the appropriate air spring valve(s) in the valve body to release pressure to lower one or more corners to bring the entire vehicle closer to level. In a leak-free system, the vehicle should never drop all the way to its bump stops as a result of ASM adjustments.
Cheers,
Don
Arnotts in the US make replacement pneumatic struts for a larger range of cars & my Jag specialists in Adelaide Australia have installed a vast number of them with no problems. Arnotts also make coil & shocker conversion kits, which I put on my last X350 & they were great. I now have an X358 with a leaking front strut & I am tossing up as to whether I should junk the pneumatics & go for coils, or press on with air suspension. I like originality, but also like reliability. I suggest you try Arnotts Suspension.
Arnotts in the US make replacement pneumatic struts for a larger range of cars & my Jag specialists in Adelaide Australia have installed a vast number of them with no problems. Arnotts also make coil & shocker conversion kits, which I put on my last X350 & they were great. I now have an X358 with a leaking front strut & I am tossing up as to whether I should junk the pneumatics & go for coils, or press on with air suspension. I like originality, but also like reliability. I suggest you try Arnotts Suspension.
Hi Craig,
I'm not sure what the quote from my previous post has to do with the point you are trying to make. Who are you suggesting should try the Arnott Industries air spring/dampers or coil conversion? I have personally installed many of the Arnott coil conversion kits, and most owners are very satisfied with them, and buyers seem to be willing to pay more for cars that have been converted to coils. I recently installed a Suncore coil conversion kit in a 2006 XJR and was surprised at how good it was. The ride was very comfortable, with what seemed to be less body roll and better control compared to the Arnott units, and at a significantly lower cost. I don't know how durable the Suncore units will be. Only time will tell. Overall, our members report that the Arnotts have been very good, though with some failed units, both air and coil types.
I personally prefer the original Wabco/Bilstein air suspension if it is properly maintained and repaired as necessary. Some owners who were willing to make the investment have had me install new OEM Bilstein B4 air springs/dampers, and I have to say, in the X350/X358 they provide a ride that is truly world-class, even by today's standards. Most current X350/X358 owners have no idea how good the suspension was when new because they only know how the air springs/dampers perform when ten or more years old.
08-06-2020, 09:27 AM
Leaking air springs
