'06 XJ8, 103K miles
Chantilly, Virginia

Yesterday after work I walked out to my car in the parking garage and found my beautiful XJ with the rear of the car deflated and sitting low on the rear tires looking like one of the city kids with his pants hanging halfway down.

I opened the back door to put my computer in the back and I could immediately hear the air rush into the rear suspension and reinflate to the proper level. I am guessing that this means that there's a leak in my air suspension in the back.

Is this a horribly expensive fix or something that can be rectified fairly easily? Is this something that needs immediate attention before it causes more damage or do I have a couple weeks to deal with it?

 

The expense is going to matter if it's simply a leaking air line or if one of the shock bladders has failed. If it continues to stay pumped up while driving, the only thing that might be damaged is the air compressor, over heating from constant running. So, I would get it checked as soon as I could.

 

Like said above, it really depends on what is wrong, and how you want to fix it depending on the actual problem. There is a lot of information in the X350 section. Use the search bar.

I have a used set that don't have any issues. I would think if one of yours is bad, sourcing a used set will be the cheapest option.

Could be something simple though. Start car, go into the trunk and listen for a leak. Spray dawn brand soapy water on the struts and coming back in a few minutes. If you have bubbles it is leaking. Use dawn, it will detect it better than cheap soap.

If your compressor constantly runs, it will burn out. If the ride is way to high or too low you can damage stuff. But at normal height there is no worry of breaking anything mechanical. Bar the compressor. You will hear it if it is constantly on.

 

OK, so what is happening ?

You get to work, park and switch off the engine and lock the car. Thirty minutes later the car goes into 'Sleep' mode. This shuts the air suspension down and if the car is left, it wakes up 24 hours later to check the ride height. Of course you're at work so return much sooner than that. However in that time any leak in the rear suspension has deflated the air springs so the car is sitting low at the back.

Now you return and unlock the car, and open a door. This causes the system to wake up and go into 'Preliminary' mode. This raises the car using the air in the reservoir only, the compressor is not used. You then start the engine and the system goes into 'Stance' mode. This levels the vehicle again to a tighter tolerance, and of course adjusts to account for your weight in the car. The compressor is now made available if necessary to recharge the reservoir and get the car to the right level if there isn't sufficient air in the compressor.

It seems to me that as the reservoir is retaining pressure during its parked period at your workplace, that the leak(s) are after the valve block. If the whole rear is low rather than one side, both rear air springs may have a leak. As Naso Lit. says, you need to investigate for leaks at the top of the rear air shocks, and the air supply lines but the air spring bladders may be leaking and that is more difficult.

Are they the original air springs fitted by Jaguar or aftermarket replacements ?

May I suggest you park the car at home, lock it up and observe if the car lowers before 30 minutes are up. When you switch off and lock the car, it goes into 'Post' mode for 30 minutes after which it switches to 'Sleep' mode. 'Post' mode attempts to level the car, so it will try to keep the car level using reservoir air. It certainly sounds like your leak is small, but obviously there somewhere.

 

Thank you for the detailed advice.

It still has the original equipment on it and it's been flawless forever. I did not last week that the "air suspension fault" alert showed up after I'd let the car sit unused for a week, but then went away after leaving it in the garage at work for a few hours.

After I arrived home on Friday, I checked it 5, 15 and 20 minutes after parking and there was no sag. I should have checked at 30 and 35 also, but hadn't seen your note at that time.

I checked it again Saturday morning and it had sagged. I left it sagging all weekend and didn't use the car. I'll use the other car for a few days and will try some of your suggestions.

I'm going to go try the "30 minute test" in a few minutes.

I'll try to get home from work a little early tomorrow and will try the "Dawn" approach. I hope it's just a leaky line and not a bigger problem.

 

It's been 35 minutes since I last opened the door and there's no sag yet. I lied down on the floor and listened for any tell-tale hissing, but none detected. I'll have to get the lift out tomorrow night and try the Dawn.\

45 minutes and no sag.

 

No sag this morning...it's been 8 hours.

This is bizarre.

 

Not totally bizarre. It could be a ride height sensor failing or the exhaust valve sticking in the compressor unit. The sensor is set to the normal ride height of the car. When weight is added to the luggage area the sensor tells the compressor to come on and raise the vehicle to the correct height. When weight is removed the sensor tells the compressor to exhaust the extra air and bring the car back to normal height. My guess, and it is only a guess without any testing, is the exhaust valve may be sticking.

 

I watched it last night for 30 minute increments for an hour and a half if there was a sag, it was imperceptible. When I went out to the garage this morning, it had sagged all the way down. It leveled out when I opened the back door and while at work, it sat for 10 hours...and didn't sag.

 

It's been sagging every time I park it now. I took it to a guy that runs a small garage locally who is trustworthy and he said it's the bag around the suspension that's leaking and he doesn't have the tools to do it. For the most part, I'm leaving it in the garage and taking one of the other cars to work so that I don't destroy the compressor.

Anyone know of someone in the west Fairfax County/Chantilly/Dulles area who know their way around the XJ air suspension?

 

From the sound of it you need a replacement spring unit. Have a look on eBay for a used one or new old-stock. You'll need the Comfort spring if your car is a normal XJ8. You can buy new Bilsteins but they are not cheap, although cheaper than going to a Jaguar dealer. Or you could put on an Arnott unit, but these don't support CATS

This UK supplier ships worldwide -

http://www.ebay.co.uk/itm/like/25169...f14=108&ff19=0

I also found this supplier

http://www.ebay.co.uk/itm/Jaguar-X35...3D251696929793

 

Given the random nature of the problem, ie sometimes it doesn't happen, I would be more inclined to go for Gatekeepers analysis; I don't see how a suspension unit itself could have a 'sometimes' leak.

 

I have a used set for sale.. Not sure if I am allowed to mention that in here, but I just did. PM if interested.

 

I agree, I don't get that either.

 

These Bilstein shocks sometimes only leak in cold weather. I think the rubber splits. And sometimes seals against itself or the steel tube.
This eats up Audi owners. The shock bleed off, then work fine for a few days. We all hope it is the easy (cheap) fix.

 

I'd be interested. How difficult is it to replace the old ones? The place I checked today wanted $450 for the labor to replace both rear sides.

 

I can see this being a four hour job to replace both. 110.00/hr and it is 450.00.

 

I would think about 45 minutes a corner sounds about right. The rear take a tad longer.

I would contact a suspension orientated shop. They should be able to knock it out at a good rate for you.

Edit×× I did not mean to mention the air struts again, I was honestly thinking I had commented on a different thread about it. My apologies.

 

My understanding is that it's the union where the air-line is joins the top of the suspension unit that causes the problem in cold weather, not the bladder itself (inside the unit).

 

On our '04 front right air spring/damper, the cold weather leak is not at the air line fitting. It is between the large red rubber top-mount seal and the metal top mount "spool."

The red rubber seal can be seen in this photo by reyesl:



And here's a cutaway view of that seal and the top mount "spool," also from reyesl:




Our cold-weather leak is from the top circular opening in that red seal, around the CATS solenoid.

The rest of reyesl's excellent cutaway photos can be seen here:

https://www.jaguarforums.com/forum/x...t-away-143111/

Cheers,

Don