Hello All,
First post and I thank you for all of the value information posted. Definitely makes ownership doable.

I have a 2004 XJR w/70k on the odo. Purchased in Feb '20 with knowledge of rear suspension rebuild.
The vehicle had a consistent leak in the system, which would not hold a ride height overnight. After rear rebuild of suspension components and rear shock replacement, she performed flawlessly, until a few weeks ago. After a 160mi drive and stopping for a quick errand before returning home, i returned to the parked car and found the front end in full dump mode. Started and waited for the compressor to cycle and the front end didn't rise back up. After getting her home to the garage, i started it up and the front lifted to ride height and after a few seconds the front end collapsed along with a distinct whistling sound.
I had previously purchased a bagpipe andy compressor rebuild kit, as a pro-active repair part, since i had no history on the compressor. I just removed the compressor, but do not think it to be the culprit, as this is an Arnott unit, and appears to be fairly new. I say this because it is too clean to be an original component.

My questions, for the more experienced, are: 1) does a rebuilt unit have a date code/stamp? The unit has 15.05.17 above the UPC code and below the P-2291 part number.
2) is there a way to pressure the system, with the compressor off, to check for air leaks?
I am suspecting a blown front left shock as the culprit, as the whistle appeared to come from the left wheel well area and based on what is see, no line fittings and/or line damage is evident in the wheel well area. Posts, I've found have faulty line tests with the system intact and suggest the lines themselves rarely, if ever fail. Only fittings, compressor or shocks.
Please help, having Covid induced withdrawals. Really need to hit the open road...

 

Struts can fail with a bang or a whistle in your case.

Fortunately I have no experience of strut leaks (fingers crossed) but I think

you are absolutely right.

You need to replace it I'm afraid.

 

Wish, I'd done the coil over conversion, when addressing the rear... arrrggghhh!!!

 

Just ordered a pair of Arnott Sports.
While waiting for them to arrive, I'd like to double check my understanding of the troubleshooting process.
1) The front system works as a pair vs. the rear working as individuals?
2) If (1) is accurate, does that mean I should be plugging both lines at the front, to see if the rear rises. All 4 corners are in a dump position (sitting at rim height, not tire height).
3) Could there be anything else i am missing?
Want to explore all options. $950 is not on my
want/nice to have list...lol.
4) Curious. What's the average mileage when the air struts expire?

 

Have you checked out the air suspension sticky at the top of the forum?

 

Nope, i missed the sticky. Thank you for the redirect and a seperate Thanks to Don B for the informative write up. Will pick up 1/8 Brass caps tomorrow and begin a more informed diagnosis.

 

Hello all,
My apologies for the delayed response. As the XJR is not my primary vehicle, yesterday was the first opportunity to deal with the issue. I ordered a new pair of Arnott Sports in the event, the strut was the issue. After following the diagnosis from the sticky, utilizing the 6mm caps, i was able to prove the driver side strut as the issue. I replaced the driver side strut yesterday and will get to the passenger side this week (Why wait for the inevitable, with 3 new ones on the car...lol). Will also rebuild the compressor with the Bagpipe Andy kit, as well (once again, why wait for the inevitable, as this is a system).
Thank you for the time and effort of the community for making our Jaguar experience as palatable and economical as possible.

Respectfully

 

Glad you got it worked out. While reading this, I was going to contribute that the compressor doesn't directly pressurize any of the struts, it pressurizes the tank in the spare tire well, and that tank supplies pressure to the struts, as directed by the solenoid valve body, also in the spare tire well. Each strut is controlled individually, both inflation and venting, independent of the other struts. Thus, plugging the air line to any one strut or pair of struts would tell you nothing about the function, and would indeed confuse the controller when it sends air to a strut with no effect, probably throwing a code as a result.

Without a data scanner, you weren't going to get very far troubleshooting the system. You were making far too many incorrect assumptions about how it works. And... Even though the struts are new, you may find that there are still leaks in the system, just not the major ones you were experiencing. Each end of the 6 air lines (1 line to each strut, 1 line from compressor to valve body, and one line from valve body to pressure tank,) is a potential leak, as are the residual valves at the top of each strut (The fitting that the air line screws on to,) so 16 potential leak points that are not actually part of the strut assemblies. These will generally be much slower leaks, but could still drop the car overnight in at least one corner.

I'm no "Professor of Air Suspension" by any means; I've only had my XJ8 Since the first week of last month, but that sticky refered to earlier, and some downloads from that thread, have pointed me the right direction with my issues.

 

Thank you for pointing out the potentials for additional issues and glad to know additional understanding of the system function is required, as you are correct in my belief of simplicity. Specifically for reminding the compressor not the direct source of pressurizing for the struts. Time saver!!!

Initially, with the car running, it would not lift at any corner. Once i plugged the front passenger side strut air line, the car lifted as normal. Also, the front left is where i heard the initial whistle of air. Checked before i left for work this morning and it is still holding, so i am hopeful this is where it all ends...lol.

 

I really don't see how plugging a line could change the system's behavior. The only feedback the controller gets is from the level sensors, the tank pressure, and compressor run time. It would see the corner as low, send air to it via the valve body, see no height increase and no pressure drop, but I'm not sure that's enough to make it think, "Oh, well, moving on, then." It has no way of knowing the actual pressure in any strut or line, just the tank itself. It also knows how much that pressure should increase while the compressor runs, I think would throw a code if the pressure doesn't come up correctly.

There are a lot of factors that are computed, though. For example, my code reader gives me height at all four corners, but there's only one height sensor at the front, on the left side; the right side height is computed from the other three. Perhaps the no-pressure-drop-no-height-change on your passenger side did compute to something for the controller...

 

What i described, is what happened and the only 'screen code' was "vehicle too low". I know little about this vehicle, but if the strut air bladder is blown, would that not create an issue? Maybe, the system isn't as independent from the tank, as believed. Also, i rarely see Jags/Rover 'flat/dumped' to one wheel. It's usually front, rear or all. Also, i have an early model with 4-sensors. Maybe that makes a difference.

 

I didn't mean that I didn't believe your description, I meant that I don't know how it influenced the system's behavior. The code I was referring to is a stored diagnostic code in the controller, only readable with a scan tool plugged into the OBD-II port. Any number of those codes would show on the dash as simply "Air suspension fault," the same way as any number of codes from the emissions system will simply light the "Check Engine" light.

 

Didn't receive it that way and my apologies for not wording it differently. Trying to get understanding of the complexities is how i view it. I just received a scanner. Once i am able to put it to use, we'll see what else may be going on.
Appreciate your input.

 

I replaced the right front strut today, even though the issue has been resolved. Figured, since the left front was original, it would only be a matter of time for the right side. After removing the right strut, I

found that it had been replaced not too long ago. It has a manufacturer date stamp of 8/2019. So, if anyone is looking for a front sport air strut, it is available. What is the best recommendation for the cores ( who pays the most for the cores)? I'm not a fan of trashing reserviceable parts and would like to recoup a portion the expense.

Thanks again for the feedback, direction and support.

 

Don't think anyone pays for our cores, or even takes them any longer.

Was told by someone there they have had a LOT OF PROBLEMS with these air shocks.

When offered an old set for free, if they sent me a label, was told no thanks

Was told they had none for sale, & were not taking any in at this time.

 

That one that you have was a rebuilt one, anyway, not a brand new one. RMT is a refurbisher.

 

I have a full set full set of used air shocks that were bench pressure tested and left in below freezing weather. They are passed but I decided to purchased Chinese made air shocks on Ebay about two months ago. The entire set was $1,000.00. They worked perfect. This winter is the first season that I (my wife) do not have dealt with leaking air shocks. I installed a set of used front air shock (less than 35k miles) that was bench tested and it did not last for a season. They were all dry rot and failed due to age and not due to miles driven. My compressor rebuilt also failed in les than six months. Forget air compressor rebuilt, after market cost for a brand-new air compressor is less than $150.00.

 

Oh well. Sounds likes scrap yard. I'll keep the rebuild just in case.

 

All is good with the R, again. Just completed a 850 mile trip to Sacramento, this past weekend. Great highway vehicle. Performed as she should and am glad i didn't compromise the comfort by going coil over. My BMW is the twisty/spirited vehicle. The Jag is for comfort.
Thanks again for the direction.