Hey everyone, sorry ahead of time if this has been answered elsewhere — I spent sometime looking through the forums and couldn't find direct answers yet.

I came out to my SV8 in the garage last night, and noticed the front passenger air suspension seemed very low. After turning on the car and letting it idle for a few minutes, all the other corners seemed to inflate like normal, but the front passenger was still all the way down.

So it seems as though I need to replace the shock on that corner. Couple questions:

1. Is it possible that there are any other problem parts other than the shock itself? Could something else be causing this, even if it's just on the from passenger corner?
   
2. I know there are two types of air suspension parts for our cars — comfort and sport. Super V8s use comfort, correct?
   
3. From reading through the forums, it looks like a lot of people have been favoring the Bilstein (OEM) shocks over cheaper parts like Arnott or A1 Cardone. I can get an A1 Cardone from Rock Auto for about $450, but it is worth spending double for the Bilstein?

Thanks!

 

1. Could also be the related connecting airline between the valve bloc in the trunk and the top of the shock: worth checking if you have bubbles when spraying soapy water;
2. SV8 has comfort suspension;
3. Worth paying the true stuff: Bilstein B4

 

Thank you, good point. I'll check that, although it seems like if that were the issue, it would probably be a slow leak, right?

 

Difficult to say.
I've been closely observing the levelling of my SV8 for weeks now, carefully noting the front and rear heights from day to day when parked for up to one week.
Sometimes it seems that there is a small leak requiring a repleneshing of the shocks during the daily "check"carried out by the system, using the stored pressure in the reservoir. That can be noticed for example when the level is higher on a morning compared to the evening before.
On other parking sequences, the level seems not to move, as if there was no leak at all.
My conclusion is that the shocks enveloppes themselves are probably leak-free and I rather suspect that the sealing system, be it at valves in the block in the trunk, or in the shock assemblies temselves may not always be perfectly tight when the car enters into sleep mode. And it also seems that the seals are more prone to this kind of loose adjustment when the temperature is colder.
So, many possible causes for leaks, at least small or irregular ones!

 

Got it. Where is the valve block in the trunk? Is it relatively accessible?

 

Manifold and valves under spare wheel on floor of boot (trunk).

 

Need to re-surface this thread...

So for the last month, the air suspension began acting like normal again. Until last night... Dun dun dunnn.

I came back to my car in the garage after work. The front suspension was fully collapsed. As soon as I unlocked the car, it began to re-inflate, and once I started it, it inflated like normal, got home totally fine.

Came to the car this morning, and the front was again fully collapsed. This time, it did not begin inflating until I started the car. It seemed to inflate like normal, maybe a bit slow. I pulled out of the driveway, and the front of the car thudded a bit differently than normal, and a few seconds later, I got the "Air Suspension Fault" error code. I pulled over, turned off the car, then back on. Suspension inflated and seemed ok, so I drove to work. All good.

I feel like the issue is that it has a slow leak which has gotten less slow lately, so that's why it doesn't hold air overnight. Since there's a leak, the air suspension probably needs to constantly be filling up with air while I'm driving, and in order to do that, the engine probably needs to be warm. Which is why it didn't want to stay inflated when I first started the car this morning, but was ok after.

I just parked at work, turned off the car and went right to the front passenger wheel. This is the corner I think is affected. I could hear an audible air leak / deflation. I know this is normal, but it didn't stop deflating like it should in the parked state. I'm sure if I go back down the garage now, it'll be fully deflated again. FWIW, I did not hear an audible leak coming from the driver side, just the passenger side.

So I think the issue is on the passenger side, and the collapsing passenger side is just kind of pulling down the driver side with it.

The big question is — does this sound like it's the shock, or does it still sound like it could be something else? An air line leading to the shock that's leaking?

 

As you're resurrecting the thread from mid December, what steps did you take to confirm your suspicions as advised earlier once it started acting up again?

Nothing really has changed (ultimately, though it self resolved for awhile?) other then an acceleration of the failure now. Soapy water will usually find your leak and confirm.

I'd focus on the line in to the top of the shock. I'm no expert on them, but it's doubtful that the bellows is torn as it wouldn't self correct for a month then start acting up again.

Beware of tightening the olive fitting too tight as well if that's where the leak is.

 

you might also reach out to the gentlemen in this thread to eliminate the air shock.

https://www.jaguarforums.com/forum/x...t-tool-164417/

 

Thanks, I'll check our that test tool thread.

Basically, the issue went away fully for about a month. The suspension acted normal while driving, and while parked each day.

Yesterday, it started acting up again, and worse than before, as I came back to it after about 12 hours, and the front was fully deflated. Reading through other posts here, it looks like it could be the compressor, or a line leading out of the compressor. And per your note, I'll check the two lines on the front shocks.

I guess the big question is — based on the behavior here, does it seem like the shocks themselves may be ok, and there's a leak elsewhere? Or it's too hard to know? I'm saying this because the car drives fine once the shocks inflate after the car is warmed up.

 

Yes just a little too early to know. Soapy water on the air shock itself and the valve block would be my first test. Compressor and reservoir would be my second soapy water test. Finally I would use the tool and test the shock.

I'm going from memory but thought the compressor pushed to the reservoir then the reservoir to the valve block for distribution. If you're hearing air leak at the front shock, compressor and res are in front down low on the driver's side. Valve block is in the boot.

for now, if it were my car, I'd focus on air leaks based on sound and work my way backwards.

 

You may be able to place your hand under the wheel arch and while lifting a bit, 'make' the leak occur more prominently.

With the hood open, it may help to locate (top of car/bottom of car) the sound.

Thanks-
Mag

 

So if that works — sort of lifting up the front corner of the car to speed up the leak — would that indicate where the leak is actually coming from? Seems like it could mean it's the shock itself.

 

That's what I was thinking...you may hear it 'venting' from the top or from below and that may help the leak's location to be determined.

Only takes a few seconds and won't cost anything; therefore seems worth a shot.

Thanks.
-mag

 

Small update — still doing the same thing. When parked/off, the front (I think just passenger side still) drops all the way down. But when the car starts, it inflates mostly like normal. I say "mostly" because this morning about 10 minutes into my drive, I got an "Air Suspension Failure" code thrown. I could tell it was still at least mostly inflated, and I just turned the car off and back on, and all was fine.

I was thinking last night. The shocks are fine (mostly) when the car is running, but they lose all air as soon as the car is off. This makes me think the shocks themselves are fine, and its the system that maintains the air level in the shocks that's not working. Forgive me for not knowing exactly how the system works, trying to learn more now.

 

Hi MrWest,

For the fundamentals of the air suspension operation, see this link from near the top of the home page of this X350 forum:

Air Suspension & ECATS System Summary: Components & Operation

The fact that your car is low after sitting but raises up after starting the engine indicates that the system is working well enough to pressurize the system and maintain the proper ride height.

The fact that while sitting the car lowers indicates a leak somewhere in the system. The leak could be anywhere, but the most likely suspects are the air hose fittings and the air springs/shocks themselves. The fact that your front passenger-side corner drops the lowest suggests the leak is at that corner. The fact that the leak comes and goes suggests that it is probably not in the air spring bladder or an air hose fitting, but is more likely at the air spring top seal. Many of us have discovered that the top seal in one of our air springs tends to leak mostly in cool and cold weather, typically 40F and cooler, but sometimes at higher temps.

If your compressor is healthy, it can generally overcome the lost pressure during one two-minute charge at startup, as long as you leave the transmission in Park until the compressor shuts off. If you put the transmission in gear while the compressor is still running, the compressor is shut off and will not run again until the car exceeds 25 mph, by which time the Air Suspension Control Module (ASM) may have triggered the AIR SUSPENSION FAULT warning.

Sean has already suggested the soapy water test, and I don't see any report from you that you've tried it. To test for a leak at the top seal of your front air spring, spritz soapy water around the central recess at the top of the unit. This part of the air spring is exposed by a cutout in the air spring tower/mount. You will see the air hose and a thin electrical cable attached to the top of the air spring/shock. Take care not to wet the electrical connector, but apply soapy water all around the perimeter of the recess and also on the air hose fitting.

You may have to wait until the suspension has dropped again, then open the hood and prepare to conduct your soapy water test, start the engine and while the compressor is running, use the soapy water on the top seal and air hose fitting. Bubbles indicate the source of the leak.

Please let us know how it goes.

Cheers,

Don

 

Thanks Don, very helpful info. I'll plan to try that in the next day or two.

 

I will add my recent experience in the hopes that it will help.
I just replaced all my shocks with OEM.....ouch.....I have a 2007 XJ8L that just hit 100,000 miles. I knew I had a bad front driver side shock as it was releasing air from the top of the shock when it got below 50 degrees. I never got any codes as it would fill fine when I started the car but I would not drive it below 50 degrees. I could audibly hear and feel it leaking from the top. I also had a rear shock that started to leak oil about a year ago so I knew it needed to be replaced.
Anyway, after having the shocks replaced, I was still losing height overnight. It did not matter if it was hot or cold, the front driver shock began to very slowly drop at about 1.5 inches per day. As soon as I opened the door, they would automatically fill with no issues. The compressor would never run over 30 seconds to fill the reservoir so I was thinking I might have a faulty shock.
Long story shortened, I took the car back in to have the shocks tested and it turned out the issue was a leak at the valve block in the trunk. The fitting that controls the front drivers side shock had a small leak that was causing the drop. They replaced the o-ring and used some Teflon tape on the fitting and problem now solved.

 

Thanks Mark, that's helpful also. Did you use the Bilstein shocks? I've been reading about Arnott, and it seems that the shocks they sell actually bypass the CATS system, which doesn't sound good to me.

I haven't had a chance to diagnose where exactly the leak is, but when I do I'll definitely check the valve block in the trunk as well. At this point, I'm 95% sure the leak is coming from the shock itself, as I can audibly hear it leaking when I stand next to it after shutting off the car.

The leak is getting worse the last coulee of days, but that could just be temperature related. I'm in LA, and it's been in the 30s and 40s at night, so quite a bit colder than normal.

 

Mr. West,
Yes, I did go with the Bilstein shocks. Like you, I did not want to lose the CAT's functionality.
Your symptoms sound just like what I experienced with the bad front shock. IMO, that is probably your culprit.