Hi 34by151,

Thanks for the details of your intriguing compressor setup. I'm not sure how we could retrofit an entire secondary air conditioning system into the X350 in order to provide additional drying by passing the inlet air through the evaporator, but it sounds like it works great in your shop.

Based on my research, all of the air dryers in the Wabco air compressor systems installed on X350s (as well as vehicles by Audi, BMW, GM, Mercedes, Porsche, Volvo, etc.) use desiccant beads. The older cars use silica gel beads. Our '04 uses molecular sieves, so I presume that at some point Wabco transitioned to these in all its compressors, but I don't know for certain. I also learned that the replaceable "cartridge" style air dryers used with large shop compressors also use desiccant beads.

Based on the terminology I found during my research, the term "air dryer" is most commonly used to describe a bed filled with desiccant beads which "adsorb" moisture in a condensed layer on the bead surfaces (as opposed to "absorbing" moisture throughout their entire volume like a sponge). The term "water trap" is most commonly used to describe a container into which water vapor condenses and collects and from which the collected water can be evacuated and removed from the system.

Still, just imagine if we could mount your shop compressor setup in our X350s.... :-)

Cheers,

Don

 

hi Fraser,
affraid you are mixing up the word expert with enthusiast!!

i have stripped many but still no expert, always learning

as don mentions the wabco system had no water trap but an airdryer full of beads to remove moisture before air leaves the compressor, my Audi too after running, gives a whoosh dispelling air but i don't think it is to remove moisture as the moisture is contained in the drier before the n111 valve, which i think this valve is opening to let air out so the compressor is not under pressure to make it easier for the compressor to start again, if it were under pressure it is more work and would put more load on the motor to start against. I don't know for sure but this would be my take on it

best regards

andy

 

I just thought I'd check my X350 technical notes on the air compressor and it states that air at low pressure is vented from the suspension system at low pressure to flow over the dessicant removing water from it, and returning it to atmosphere. It doesn't say when this is done but I have assumed it is the "whoosh" of the air exhausting after a run, after engine shutdown, as I regularly hear. Maybe Wabco can tell us !

 

Fraser,

I've made the same assumption regarding the whoosh of air exhausting from the compressor. The manual only states that the ASCM opens the exhaust valve from time to time to reactivate the desiccant as you describe. The whoosh may also have something to do with leveling the vehicle in your chosen parking spot, which is another thing the ASCM apparently does.

I have spoken with three different customer service representatives of Wabco, two in Michigan and one in South Carolina, and none of them could tell me anything about the Wabco air suspension systems for passenger cars. They all referred me to the German or Poland operations, but could not give me the name, email address or phone number of a department to contact in those offices. My Wabco pump is marked "Made in Germany." The only contact information for Wabco Germany that I could find online gives a physical address but no email address or phone number. Perhaps one of our Germany-based members can help us get more information from Wabco.

I'd also love to talk with an engineer at Bilstein about the air shocks, their construction, and the availability of replacement parts. If Arnott can rebuild these shocks, why can't we?

Cheers,

Don

 

Don,

I was just pointing out that the water remains suspended while the air is hot
Thats why you setup a shop compressor with water traps after the tank in hope tyhat the air has cooled. The other nethoid opten used is the drip pipe setup.

In any case you get little to no water removal from hot air, it needs to cool for the water to separate. At this point whatever trap you are going to use can function

A small punp like the ones in our cars will allays pump hot air.
The only place for water to be able to cool and separate is the tank in boot bat that all depends on how much the air is pumping.
If your really worried about water a water trap between the tank outlet and valve block is the best place to trap water

The woosh of air you hear is vent solenoid that is mounted with the compressor
The whole system is controlled by the air suspension module. For the compressor there are 3 main items

Power contol to the compressor (ie compressor on/off)
Vent solenoid (mounted on the compressor)
Pressure sensor (mount with the tank)

The ASM commands checks the compressor upon start by commanding it to pump and verifies an increase in pressure. If this goes over 212psi it will then shutoff the compressor and vent.
As air pressure drops with lower temps the tank is rarely at 212psi at start-up so the compressor will pump for up to 5mins attempting to get the tank up to 212psi. If this does not occur you get a suspension warning.
Assuming this is worn compressor this is where andy's kit comes in.

You will also note a minute or so after you shutdown the engine you hear a vent. This is a good thing as it lets you know your tank was at full pressure when you shutdown.
The vent is used to depressurize the line from the compressor to the tank. This is to allow for easy start-up of the compressor. The same thing happens as you are driving but you will never hear that.
This is exactly the same function that a shop compressor has when it stops pumping

Cheers
34by151

 

Hi 34by151,

Yes, I agree that between the air reservoir tank and valve block seems to be the generally-accepted best location for a water trap on a vehicle air suspension, as I mentioned in a previous post.

Your comment about the air in the system cooling and losing pressure is a good observation and is probably a contributing issue to the common problem of the suspension leaking down in cold temps. On our car, at least, it seems that the right front shock leaks audibly when the system pressure is low, and I can feel air escaping from the top of the shock around the electrical connector. But once the system pressure increases to a certain point, the shock no longer leaks, at least not audibly. Something in the shock seems to require pressure in order to seal properly.

Regarding the compressor run time in the X350, the "Jaguar Service Training Course NP04 for the 2004 Model Year, New Technical Introduction," page 7-13, states that the compressor is allowed to run "for a maximum of 2 minutes to control piston and cylinder head temperature." I don't know if this run time was extended for newer model year X350s to the 5 minutes you mention - do you know the source of that info?

Many vehicles that use the Wabco compressor have a temperature sensor fixed to one of the cylinder head screws, but in the X350 compressor temperature is controlled by the ASCM using an algorithm and the ambient air temperature sensor signal to calculate the compressor run time, not to exceed 2 minutes (on the '04 MY anyway). After 2 minutes of run time the ASCM will shut off the compressor and allow it to cool. "The time limit before being allowed to re-run depends on vehicle activity and is generally around 30-40 seconds but not longer than 120 seconds maximum."

According to the same manual, the pressure developed by the compressor is given as "nominally 15 bar / 218 psi," and the pressure relief valve opens at 17.5 bar / 254 psi (however, the the Service Manual states the PRV opens at 17 bar / 247 psi). According to Andy's website, the PRV on the Audi Allroad compressor is adjustable between 14 bar and 16 bar settings.

Before I rebuilt our Wabco compressor, I thoroughly studied the above-referenced Jaguar new model service training manual (the entire manual, not just the section on the air suspension), the X350 Service Manual section on the air suspension, the Wabco ECAS passenger-car air suspension manual (Jaguar ECATS appears to be Jaguar's self-branded version of the Wabco ECAS system), all the helpful info at Bagpipingandy's website and in his YouTube videos, all the info in the past posts of Jaguar Forums, Jag-Lovers, JaguarForum.co.uk, Wabco's websites and online parts catalogs, many websites about air suspension systems on other makes such as Land Rover, Audi and Mercedes, and the "how to" online manuals at several vendors of after-market air suspensions. I included some of the tidbits I learned in the photo captions of my 7-part photo documentary on the rebuild of our pump (see links in an earlier post).

I'm sure there is more to learn about the air compressor, but what I'd really like to learn about now is the air shocks and how to rebuild them so they don't leak!

Cheers!

Don

 

I've seen docs sating 212 all the way up to 230's however the Air suspension module does not really care it just reading the voltage from the pressure sensor. This is resistive sensor so it will vary from one to another and also with temp and hence the differences.

The main point is the pressure is much higher than the 4wd type compressor can match.

Leaking from the top fitting is well documented. Its possible your seals when pressure is applied due to expansion though

Regards the time again I gave you the maximum, you are right different firmware versions have different limits. I was generating the mil code. You will get compressor cycles that effect this based upon run times as well.

At then end of the day if you have the suspension drop you have a leak. The challange is finding it.
You have already found a leak in the tower that needs to be addressed but also check the vavle clock and leaks at the compressor/valve
Its possible, for example, you have a sight leak at the valve. IE not fully closing
Dont discount you may have more than one leak

Cheers
34ny151

 

[QUOTE=34by151;927008Leaking from the top fitting is well documented. Its possible your seals when pressure is applied due to expansion though

You have already found a leak in the tower that needs to be addressed but also check the vavle clock and leaks at the compressor/valve
Its possible, for example, you have a sight leak at the valve. IE not fully closing
Dont discount you may have more than one leak

Cheers
34ny151[/QUOTE]

Hi 34by151,

Yes, I've read countless reports of the shocks leaking from the top, but so far I haven't seen an account of someone actually opening up one of these shocks to see what is going on inside. The closest I've found was on a Mercedes forum and also a replacement "spring cap" for a Ford air spring that seals the top of the air bladder and is available as a replacement part. If you are aware of any documentation on a rebuild of the Bilsteins in our X350s I would be grateful for the reference.

You raise another good point that there may be more than one leak in the system. I did thoroughly clean the check valve in our compressor as part of the rebuild, and I cannot audibly detect any leak from the compressor after it charges the system and shuts off. I have not yet checked for leaks at the valve block but since I know for certain there is a leak at the top of the front right shock that's where my attention is focused for now.

Cheers,

Don

 

This pertains to my 2004 XJR. I live in Southern California, so I don't have the cold weather considerations.
While driving on a flat street at about 30 mph, I heard to sort of thud. I thought I ran over something, but I had not. Within about 200 yards, the air suspension fault light came on and then the vehicle too low warning. As I turned the corner, the tire rubbed the wheel well. By the time I got home, about 1.5 miles, the whole front of the car was very low. When I start the car I heard the compressor and pump circulating. I also hear some kind of leak from the left front of the car. I removed the air hose line to the top of the strut to check the O-ring. IO started the car and there seemed to be a good flow of air from the hose.
Any thoughts on what the problem may be? I can't drive the car.
To make it worse, a 16 year old ran a red light about 5 weeks ago and totaled my XKR convertible...so I am without a car.

 

The thud noise sounds like your air spring rubber diaphragm has let go, so you need to get a service exchange unit from Arnott. Or you can buy a new one at mega-bucks.

 

Thank you for the input. I thought the shock was bad. The mystery is that both sides of the front of the car are "too low". It is only on the passenger side that I hear the hissing. This air system is a real enigma for owners who don't work on their cars a lot.
I am very reluctant to go to a repair shop since the last two I went to were real rip off artists and did shoddy work. That is a different story.

 

Ken,

If you want to see exactly what the replacement involves I suggest going to YouTube and looking up Arnott air suspension install for the XJ. At least you will have an idea of how long the procedure takes as well as whats involved so when you talk to the dealer or Indie shop you know the truth and the time it takes. Or perhaps you may feel you want to tackle it yourself, but either way you may find the video useful. Good luck

Also, you can replace just one , but more than likely will have to replace the other as well.

 

Thank you motofreak72. I did look at the Arnott site. They make it look so easy. I am debating whether I will tackle it myself.
Be well

 

No problem, Just remember if your going to tackle it by yourself have a breaker bar and the right size Torx bit for your ratchet...i believe its a T55 or T60 (its been a minute since I looked at it) you will need one. Other than the tools it really wasn't to difficult to perform and I did it without a lift, one side at a time in my garage. Have fun

 

Thanks again. I was curious about the Torx bit. I don't have one lying around.
I think I may give it a try this weekend. Stand by for details.

 

Ken,

Most chain auto parts stores carry a set of Torx bits to fit 1/4" and 3/8" ratchets for around $20.00 or less, and may also carry individual bits. Lowes, True Value and other hardware/home stores also carry them. Just be sure you get a set with a bit large enough for this job or buy an individual bit of the correct size. T55 and T60 are relatively larger sizes.

Cheers,

Don

 

OK I went and looked and it is for sure a T55. Get a 1/2" drive as you'll need to put some pressure on it to break. Auto Discount sells them individually for about $5. I went to Harbor Freight and picked up a 1/2" Breaker bar for $6. Sure its not a long term tool , but its paid for itself tenfold. As long as you have a decent Jack and hand tools coupled with the Torx and Breaker you should have no problem. On the first side I was using my smart phone and watching as I went along to make sure I was doing it right. By the time I was done I found the other-side was a breeze. Keep us posted.

 

Thanks again. I ordered the parts from Arnott yesterday. I'll visit the parts store and get the Torx bit and breaker bar. Stay tuned. I hope this has a happy ending.

 

Just to up date my progress, I received my piston ring from Andy last Friday. I took about a week which is not bad coming in the mail from the UK. I also just received the material for refilling the beads in the "air dryer."


Since the temperatures have now climbed out of the -10 F to 20 F range the suspension system works perfectly! This leads me to believe that moisture is collecting somewhere and freezing up the system in these Artic temperature's. Regardless, we are stuck in the 30's F this week and as spring has to get us into the 50's F any day, I will take this compressor apart and attempt to find the root cause.


Don B. has done a lot of research on this compressor along with Andy. I intend to compile this wealth of information, so that someone can identify when the compressor is the issue and have simple instructions to refurbish it plus source the parts. I have done this for brake jobs, oil changes and windshield wiper blades and everyone really appreciates it.


May goal is that in the time it takes to research through all these threads, you can just use the time to economically refurbish the entire compressor.

 

Heres my update. Received Andy's ring around 4 today and installed by 5 in my garage. I've become quite good at taking this compressor out and apart, anyway buttoned everything up and no more amber light. Thank you Andy for producing a high quality replacement as opposed to the garbage wannabe ring I purchased by mistake. Now even though I don't have a light on and she seems to be level and ride real smooth I do notice a constant release of air from the compressor at almost every stop...maybe a little more than normal. Roughly happens when I brake at 30 mph around my area. I drive...come to a stop and pfffttt. Turn... drive a little and come to a stop pffftt. This isn't under heavy braking mind you. Again, I don't remember it being constant like that. Anyone foresee another issue I'm missing or is this just normal.