I was thinking along the same lines as far as supply voltage to the controller, basically cut the wires supplying it, put B+ on the one and an ignition-controlled relay on the other.

Compressor kit ordered. Being in the US, I searched the US eBay site for him and found he has a distributor in Wisconsin. 47 bucks shipped.

 

Waiting for the rebuild kit to arrive. Meanwhile, I loosened the fittings to let air out of the front, let them drop low, and when I started the car it leveled up absolutely correctly fairly quickly. I haven't driven it, just started it in the parking space.

There is an issue with the fitting on the left front... when I tried to loosen the nut, it pulled the entire fitting with it, not just the nut with the compression ring inside. I tightened it back up and used the brown air line at the valve body to release air. That one seem to be th emost difficult one to get a wrench on, of course, since it's the one I need; the valve body casting interferes with the wrench path.

I am fairly certain I have a weak compressor, as the sticky describing the air suspension says the pressure is normally kept above 9 bar, and most of my readings were in the high sevens to high 8s, with one reading (and only one) over 10 bar. we'll look for improvement with the rebuild.

EDITed to add, someone had put some sealant on that fitting for the front left at the valve body, which of course isn't there any more. In a couple of hours, both fronts had sagged significantly from when I ran it earlier. I started it up, got a "too low" warning, but it leveled up in short order, and I went to the grocery store without incident. Saw pressure over 11 bar at one time, but it was under 6 bar when I started this last session.

The right front dropped a bit, too, between the two session, but not as much as the left. Also, the fizzy fitting in my first post was the left front, and that was before I broke the sealant someone had put on the threads.

 

wfooshee;

In post #17 you mentioned your front end raising 70-80mm.
Do you know if the front height sensor(s) reported the height as excessively high?

The reason I ask is if the height sensor(s) showed height to be low, we would expect the ASM/valve block to be forcing more air to the front. I would suspect a height sensor, or height sensor signal issue.
If on the other hand the height sensors detected the height as excessive is would appear as if somethign was allowing unnecessary ait to leak by. I might suspect a valve block solenoid issue.

Best Regards, william

 

Height sensors matched what I saw. Today, also, they started low after I let the air out, and I saw them raise after starting the car. This one drive a week or so ago is the only time I've seen it do this, and I've left the car parked after that until today.

I'm wondering if it's not able to vent because the compressor exhaust is blocked or won't open? Isn't there a solenoid on that? When the kit arrives, we'll see what I find there.

Also, I forgot to mention earlier that I cleared the C2302 and it did not reappear today.

 

Yes, the only (intended) vent in the entire air suspension is via the exhaust solenoid valve mounted on the air compressor. The compressor includes an air dryer cylinder filled with molecular sieve desiccant beads to adsorb moisture from the incoming air, and from time to time the exhaust valve opens to allow dried system air to vent through the desiccant to partially reactivate the beads. But over time so much moisture collects in the compressor that the desiccant beads cannot adsorb it all, and it finds its way past the dryer and into other parts of the compressor and suspension system. When you replace the piston ring in the compressor, also disassemble the dryer cylinder and clean the rust off of the leave valve at the inlet end of the cylinder, and also remove the exhaust valve and high pressure relief valve and clean all the rust you find in those.

Cheers,

Don

 

OK, kit received, compressor out, piston ring and cylinder o-ring replaced. I knew I'd have a desiccant issue when I removed the compressor outlet fitting at the beginning and water dripped out... Anyway, the existing piston ring had obvious signs of wear:


On opening the desiccant cylinder, the spring is very rusty, and as I removed the plate, the desiccant inside is so wet it's clumped together. Also, the felt washer behind the metal disc (a filter, I assume) is soaked. Here's some of the desiccant dropped onto a paper towel, and a picture of that felt disc. You can see how much water the paper towel is getting!




Question: does this come out? I don't want to break it, but there's obviously a bit of water behind it, and I'd like to clean all of this up as best I can. Don't want to give the new desiccant that much work just starting out! Also, gonna have to source some desiccant beads...


The outlet solenoid was much cleaner that this; it had a bit of green gunk, which I cleaned up, but no rust.


EDIT: After sitting a couple of hours on the table, that water is evaporating, the cylinder is drying out nicely. Also, the felt disc at the bottom came out. It's also quite wet, but should dry out after a while.

 

I don't recall figuring out how to remove the inner cylinder, or I was worried about breaking the old brittle plastic. You could try blowing out the water with compressed air, or put the entire assembly in the oven at its lowest setting (e.g. 150°F) for an hour to dry out the moisture.

You can also dry and partially reactivate the desiccant beads by spreading them out on lipped cookie sheet or similar cooking pan and placing them in the oven at 450°-500°F overnight. The beads are molecular sieve and you can find sources with a little research. I used 4 angstrom (4A) beads suitable for adsorbing water, in diameters of approximate 1/16" and 1/8". McMaster-Carr (mcmaster.com) is one source.

Cheers,

Don

 

It's actually drying out just sitting on the table.

 

According to my research, in order to fully reactivate molecular sieve beads, they must be baked for 15 hours at 400°-600°F alternating between a nitrogen atmosphere and complete vaccum, so if they just dry naturally they're not going to be reactivated to the same degree as baking them overnight in a home oven.

 

I'm not drying the beads, I've tossed them. I'm talking about the cylinder itself.

 

Gotcha. You can encourage the cylinder to dry by swishing some denatured alcohol in it to mix with the water and help what moisture remains to evaporate after you pour out the excess. This also works with headlamp assemblies. Compressed air will speed up the drying/evacuation.

 

Question about fittings at the struts and solenoid body: If I'm working on a leaky one, do I need to replace the nut and olive as well as the o-ring, or will a new o-ring be sufficient? Or is simply try the o-ring and see? Both fronts leak down pretty quickly after venting them last week to get them down from redneck pickup truck mode...

I know I've got work to do on the left front, as when I tried the nut at the strut, it actually turned the residual valve underneath, so I'm pretty sure I'm going to have to cut that air line so I can spin the valve off, then separate the top nut. It's obviously been overtightened if it won't loosen separately, or possible someone gunked it up with sealant...

 

You can probably hold the brass pressure-retention valve with Vise Grips/Mole Grips in order to loosen the air hose fitting. The valves have O-rings that can be replaced, but the hose fittings just rely on the olives, which technically should be replaced but can sometimes be reused. Jaguar instructs to cut 12 mm off of the end of the hose to provide a fresh mating surface for the new olive. Try to cut the hose cleanly and as close as possible to 90-degrees.

Cheers,

Don

 

Compressor reassembled and reinstalled. Haven't fixed any of the leaky fittings, yet, so I expect the car to sag tonight, but it didn't jack the fronts way up like it's done before. The vent solenoid in the compressor wasn't rusty, but it was corroded, green gunk all over it, and that got cleaned out. Time will tell if the suspension will behave itself, now, as my driving this evening wasn't any great distance or time, so I hope I'm not speaking too soon!

 

So after the compressor rebuild, the suspension doesn't go wonky any more, like huge lifts, but it still sags within a few hours, and still throws the C2302 code within a few minutes of startup. Once the code is thrown, the system gives up maintaining the pressure and the compressor will not run until the car is shut off and restarted. With my sag rate I could drive for an hour or two and be OK. Also, when it's cold out it does take longer to come up to height, even though it's not freezing.

There was one serious leak still, where the left front line comes into the solenoid block. Fixing that didn't really change anything, so I may have bad struts. There are no fittings in the trunk or on the struts blowing bubbles any more, and the car still sags and eventually throws the C2302.

So I bit the bullet and ordered the Arnott C-2745 coilover kit from Rockauto today. Even if the one leak fix made it perfect, I have no idea how old these Arnott air springs I have are, and I have no paperwork on them. Not being the original purchaser, I'm not sure their lifetime warranty applies even if I DID have the original receipt for them. Metal springs are on the way, to hold the car up as God originally intended!

 

Raised the car Saturday morning to swap the coilovers in. Found that my front upper ball joint boots are trash, and the replacement in a whole upper a-arm, with the new ball joint being part of that. Of course, installation requires removal of the shock!

I decided to economize the work and stop until replacement a-arms arrive. I mean, why remove the shock again next week?

 

Yes I pretty much followed your path on a 2008 XJ I was working on for a friend. Rebuilt the compressor, fixed leaks still fighting the compatibility errors. Finally had a failed front air shock.
Installed the coils from Arnott. Good repair and totally fixed the cars worst feature. Car was extremely reliable after that point too. Yes I could feel a bit more of the road surface in the car but only because I drove it back to back with air then springs. It's a good upgrade.

You will find ALL the upper ball joint boots are trashed at this late date. I don't bother changing them anymore until I get clunks or noise. The upper ball joints have almost zero load on them and it's a cosmetic problem. In fact I have never seen a worn out upper front ball joint.
Change them if you want and you can just replace the boots too. That's much easier.
.
.
.

 

Somewhere in the forums one of our members posted the dimensions of the upper control arm ball joint boots. With that information, you can order just the boots from sellers on eBay.

Cheers,

Don

 

Here's a UK supplier
https://www.balljointboots.co.uk/index.html

 

OK, coilovers done, Arnott C-2745! One weirdness during the install: even though the right rear was not sagged, it vented no air when I removed the line!

The fronts were easy! Once the car was jacked up, it was about 10 to 15 minutes each side. The factory put a T-60 Torx bolt at the bottom of the strut, which I had to buy a bit for. Arnott cleverly supplied an 18mm hex-head replacements for those:


The procedure at the front was to remove the sway-bar link from the lower a-arm and remove the upright from the upper ball joint. This allows everything to move around enough to get the struts out and back in. Also, these fasteners have nothing to do with the alignment, so I'm not worried on that count.

I did not replace the upper a-arms as discussed previously, after reading the comments about that. I'll find some boots and get those on the ball joints. Rockauto has a return pending, as I did buy those.

The rears were an absolute pain in the buttocks! The only thing to remove (aside from the strut bolts) was the bolt for the tie rod, but again, you're not messing with the alignment adjustment, just the end bushing. I had no helper, and someone at the top while I shoved the strut in from the rear would have been a great help! The rears go into a bucket at the top, and you can't see the bolt holes or the bolts when it's up there. I had to prop the strut up with a jack, go up top and look at which way it needed to move, go to the bottom and try it. After up and down a couple of times each side, the bolts went through. Raise the jack enough to keep the strut in place whilst I went up top and fastened the nuts.

Then I couldn't shove the a-arm down far enough to line up the bottom bolt. Both sides were hanging, so it wasn't the sway bar holding it up. Back with the jack to actually compress the strut a bit before I could insert that bolt. I expected the second side to be easier after the frist was in place and unjacked, pushing that a-arm down, which should have used the sway bar to push the other one, but NO!! I had to repeat the jacking process, and I was probably 45 minutes to an hour at each rear corner!

Before and after:


If I hadn't read on here somewhere that they sit high on initial installation, I would have panicked!


After just a 15-minute drive around the immediate area, it sits better. Still a bit high, but time will tell.


The car is TRANSFORMED! Ride quality is immensely improved, not just from the air struts bottoming out (they didn't, unless I got impatient when starting and didn't wait for the morning lift,) but the air struts just rode harshly, much more so than I expected, even on my test drive before I bought it. That said, potholes and the like would bottom out that corner of the car, to the point I was concerned about my wheels a couple of times! On my first drive, I intentionally used a couple of those, and the car handled it very well. I really wasn't doing this for the ride, though, I was doing it because I gave up on fixing the air system.