Has anyone seen this failure on our pump motors? I think mine may have bit the dust.

I had been getting an intermittent "AS Fault" warning, but the car was not low and it would always go away on a restart. I actually just bought 2 new Arnott front springs to replace my leaky old ones (leak in cold weather, no issues in summer) that just arrived yesterday.

Today the ASF message is on for good. The car is not low, I think the exhaust valve has stuck shut based on my observations. Wish I had the SDD to actually read these codes... I started the car and it lifted the front 1/2" as usual. Drove down the street, felt the pump come on, then as I slowed to stop (when the compressor should stop and vent) the ASF message came up.

Had already rebuilt this pump with one of Andy's kits a while back. Guess I can't be surprised if the exhaust valve has gummed up. Is there any way to take the pump apart and check it, or clean the valve? I assume it's gummy with moisture from inside the system.

 

SDD would probably allow you to reset the code after the strut change.

I read somewhere that someone released all the air from the system by removing the two front strut air pipes and allowed the vehicle to drop. Then reconnect and the pump ran and system reset itself and the AS fault light distinguished on the next engine startup.

I don't think I have read about exhaust valves clogging up on the forum yet, so this could be a new one for me. I had my pump out and done the o ring change, but never thought about checking or cleaning the exhaust valve as no one had mentioned it before as part of the replacement/cleaning process.

Keep us posted.

 

trosty,

There have been numerous mentions on this forum of the exhaust valve possibly corroding and seizing in either an open or closed position. I may have been the first to raise the possibility after rebuilding our air compressor and finding corrosion around the check valve between the cylinder and the air dryer. See some of the photos in albums 3 and 4 below:

Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page

At the time I rebuilt my compressor, I was aware of the exhaust valve and the pressure relief valve, and I considered removing them and inspecting them, but I didn't have enough information to know if I might be opening a can of worms, so I decided to leave them alone and see how the compressor would perform with Andy's piston ring (and new desiccant beads). All has been well so I haven't been back into the compressor.

However, several members have reported symptoms that have caused me to suspect problems with exhaust valves. Symptoms such as the compressor running but never raising the car (EV stuck open?), or the car raising too high and never lowering (EV stuck closed?). If I'm not mistaken, one of our members has now opened his EV and posted photos. It may have been abonano but a quick search of the forum didn't turn up a hit.

Michael,

The EV will not usually open just because you've slowed to a stop. The most typical time for it to open is shortly after you have put the car in Park and turned off the ignition. At that point it may open briefly to allow any corner that is high to lower for leveling purposes. Some members have postulated that this also relieves a little pressure in the system to make it easier for the compressor to restart, though I have not found any confirmation of this in the literature.

Based on your symptoms, I would not suspect the EV. There are plenty of other issues that can cause the ASF. You really need to read your codes. There are a few suspension "P" codes, but mostly they're C, B and U codes, so you'll need access to SDD or a system that can read proprietary Jaguar DTCs. I wonder if one of our members with SDD is close enough for you to meet up?

Short of knowing the codes, you can only guess. If I were guessing, I would clean the electrical connectors and ground at the ASM (behind rear seat back) and compressor (ground is behind the left headlamp), and the connectors at the valve block and each height sensor. If no improvement, I would consider replacing the Air Suspension Relay (R1 in the Front Power Distribution Fuse Box).

In case you don't have it already, here's a link to the best description of the system we've found so far:

http://www.mediafire.com/view/7rdkgg...on_Section.pdf


Also, when cleaning aluminum ground studs welded to the body, note that the torque spec is just 6.5 ft. lbs. Several members have snapped a ground stud off by accidentally overtightening the nut.

Cheers,

Don

 

I pulled the ASM fuse for a few minutes and let it reset. Today it started up fine and recharged the reservoir, pump cycled about 3 times, no ASF messages. I will change the front struts and then see how it acts.

Hi Don, I had read your dryer rebuild a while back with great interest. I did the re-ring from Andy's kit around 60k miles, but did not touch the dryer at that time. I remember from my Cadillac compressor (I think also a Wabco brand as Jag uses) that the desiccant does not last all that long. The internals of that pump were rusty and the exh valve would not function. After I get the struts replaced, I'm going to look at rebuilding another unit with a piston ring and desiccant. In the Cad the valve was not serviceable.

Regarding the exhaust valve, my understanding is that the exhaust valve always opens at the end of the compressor cycle. This is the "puff" sound you hear from the front left as the compressor stops. Exhausting to lower the vehicle requires the exhaust valve in the compressor and the valves in the control block to open at the same time, and you get the purge cycle to lower the car.

But yes, codes would be ideal. I hate guessing, but I don't have a spare laptop I can use to lock up the SDD software.

 

Our daughter and son-in-law lived in Wake Forest for the past three years but have just moved to the Chicago area where she's beginning her doctoral program. If I had known earlier this year I could have brought my SDD over and met up with you somewhere.

I would assume there is a good independent mechanic somewhere in the Raleigh-Durham-Chapel Hill area with the ability to read your codes without charging you an arm and leg. You might post an inquiry in the Lower Atlantic and Mid-Atlantic regional forums to see if a member can recommend a mechanic within an easy driving distance.