I agree. I much prefer air suspension / auto leveling and have had it on the last three cars. I have a leak and the 'air suspension error' but have not determined where it might be yet. What is odd is that if it is warm (60F+), it is fine. But when it drops to the low 50s, especially when driving fast enough for a lot of cold air to get into the engine compartment, I'll get the error and the car will settle / air bags deflate completely. So it doesn't seem that it would be one or more of the bags since the whole car settles. I've done the rebuild to the compressor, so don't know what else it might be. But I'm bound and determined to figure it out because I'm not going to springs.

 

What upper bolts were loosened?

 

This happened more than 5 years ago, so maybe I didn't remember that clearly.
You are right, there were no bolts to loose, now I think there were 2 nuts on threaded rods.
At that time I was really worrying about exchanging the complete suspension for coil springs.
But as it turned out this was not necessary.
So this is a true story.
You should give it a try, slmskrs.
After applying the anti-corrosion spray the suspension worked without flaws for almost a year until I sold the 12 year old X350 when love turned to hate.
Maybe I'm a spoiled child who drove too many Mercedes's.

 

Yearly Krown rustproofing may prevent this happening. If done well it penetrates and lubricates most everything except on the interior of the car. My 25 year old, 720000km, van is still on the original bushes and nuts and bolts come apart like new. I have had the X350 done but have not had enough time to see if it can save the British rubber etc.

 

Same as all suspension parts, struts, bushes, or whatever, all of them are Made in Germany (as they are Wabco, Bilstein or Lemforder). So not British rubber that much...

 

The car manufacturer usually decides which material is used for the supplied device, which determines cost, durability and reliability of the device.
For instance, aluminium alloy or stainless steel, polyethylen or ABS, polyurethan or caoutchouc (natural rubber).
On some high quality cars even bigger ground cables are soldered to the cable shoes to insure low resistance over time.
Cleaning electrical contacts and treating the ground points with battery pole fat prevents control unit failure and inexplicable errors.
When I got my X350 none of the about 22 ground points were fattened.
As far as I remember 3 control units and 3 ground points are parts of the suspension system, so these should be checked and treated ...

 

Thanks to everyone on this thread that are trying to keep their air suspension systems working!! Great Stuff!!

MY TEMPERATURE-RELATED SYMPTOMS:
* If it is cold (<55/F12C) in the garage, I would almost immediately get the 'Air Suspension Fault' message, and sometime 'too low'. If I leave it overnight in the winter and it is down to the 40s (<10C), it will definitely have no air and give me the error in the morning.
* If warmer, no problem initially, but at highway speeds (something getting cooled), suspension would drop and I'd get 'Air Suspension Fault' and very harsh ride. Used to never happen in warmer weather, but now I can drive down the freeway for 10 minutes when it is 65F/16C outside and it will lose air and give me the error.
* If I shut the engine off and immediately restart it, the error message goes away and the front raises. But if I'm still driving down the freeway with air cooling whatever part is faulty, the same thing happens again (drops, error message)


TESTS COMPLETED, ETC:
* Rebuilt compressor about two years ago thinking it would solve the problem, but it didn't
* Put gauge at left front airbag connection. Bag is not leaking, but unless the car sits for several days, not enough air leaks out of the system to drop the car anyway (if it's not too cold)

TESTS TO DO:
* Move the gauge system to the right front air bag connector and repeat. Based on what I've read, the front (both sides) operate together rather than independently. So, moving the gauge to the right side will only show me if the right bag is leaking (when I isolate the bag with the gauge).
* Extend the line to the gauge so I can bring it inside the car and watch it.
* Confirm if it is just the front or both front and rear that loses air. I've seen the whole car low when it has sit for 3-4 days. However, I don't know if it is just the front or both. When it happens next time, I'll pull over first and look.

TEST EQUIPMENT QUESTIONS:
* There are a lot of error codes in the manual, but I don't see them with my basic ODB reader. What is the easiest/cheapest way to get something that will give me these codes? The extracted data that was graphed was very interesting although I just want to see codes.

FINAL QUESTION (for now):
* Has anyone experienced this issue of cold temps causing failure errors?

Thanks,

Gordon

 

Hi Gordon,

The most common point of cold-weather leaks is the top seal of one or both front air spring/damper units. The top seal is a large rubber molding that fits around the aluminum top plate in the assembly and is supposed to prevent air from the bladder or bag from leaking past the top plate. But with age, the rubber seal hardens and loses its compliance, and in colder temperatures the aluminum top plate contracts and opens up small leaks between the plate and seal.

One way to identify a top seal leak is to spritz soapy water in the round recess on top of the air spring, taking care not to wet the electrical connector for the ECATS. Bubbles indicate a leak. Of course, this only works in colder temperatures when the leak has opened up.

Unfortunately, the top seals are not available separately because they are not replaceable, due to the crimped assembly of the air spring/damper units.

I have been experimenting with techniques for repairing top seal leaks and have two vehicles that seem to be successfully repaired, so when I get the time I will post details of my experimental technique.

Cheers,

Don

 

Thanks Don. Dumb question (because I haven't looked): I assume I need to pull the plastic wheel well off to get to the air bag/damper where this plate is, correct? One problem with the issue is that when I get off the freeway, by the time I get home, it's warm enough inside that it tends to hold air. I guess with the wheel well cover off, I could turn the steering wheel to lock so I could have quick access to spray some soapy water.

I'm interested to see how your experiments have worked. An additional ignorant question: Is the damper and air bag one unit? I know I changed the shocks in my '97' and I'm pretty sure I just replaced the shock. Then again, while I would have sworn my '97 had air suspension, now I don't remember; could have been conventional.

 

Hi Gordon,

Sorry for the delay in responding. Yes, the air springs are combined with the shock absorbers/dampers into assemblies that can only be replaced together. The air spring bladders are not separately replaceable by mere mortals due to the crimped construction. You can remove the shock from the bladder/housing/top seal assembly, but you cannot easily access the bladder to replace it and reassemble the unit.

Access for checking the top seals is easy on the front units. Just open the hood and find the tops of the units visible at the suspension towers. The air hoses and ECATS electrical connectors are clues that you've found the right spot. This is where you spritz soapy water to test for leaks. Just take care not to wet the electrical connector.

For more information about the system and its operation, see this post:

Air Suspension & ECATS System Summary: Components & Operation

Cheers,

Don

 

Thanks Don!! I'm wondering if it's best to jump to that thread to keep info in the same place.

I previously sprayed some soapy water over the hose connector and there were no bubbles. That said, unless it sits for a few days in the garage, it doesn't drop. Last night while on the freeway for 5 miles (around 50 F temp), it dropped and the error came on. Got off freeway and at light, shut off engine and restarted. It came back up.

So my problem is checking for leaks when it drops since it's usually when on the freeway with cold air blowing. I will leave the car outside tonight and it will probably have bottomed out since it will be low 40s overnight. So I'll check it in the AM.

I just ordered a scanner that the manufacturer has told me will read all of the air suspension codes. That will be very interesting (will arrive next week).

Gordon

 

The air hose connects to the unit toward the outer perimeter. The top seal usually leaks at an edge of the central circular recess around the ECATS electrical connector, or through one or both of the small holes (approx. 1/4 in. / 6 mm in diameter) in the top of the air spring housing through which you can see the rubber of the top seal. These holes may or may not be visible with the unit installed in the car - I can't remember. I'm away from home and can't look at an X350 at the moment, but in my mind's eye I can see the two holes in the top of the unit, about midway between the center, where the electrical connector is, and the outer circumference. So you want to spritz your soapy water specifically in the circular recess and on those two little holes if you can see them, then start the engine and let the compressor run to pressurize the system and watch for bubbles that will indicate a top seal leak.

P.S. You're fine to leave your posts in this thread, or we can move them to your own thread. That other thread was really meant as a reference on the air suspension system and not a collection of members reporting their specific issues.

 

Thanks Don.

Long story short, I left the car outside overnight to get it cold (in the 40s). I sprayed a lot of soapy water all over the tops of both front shocks (keeping it out of the electrical connector). It hasn't dropped overnight, so I dropped it (I have T's, valves, a pressure gauge, and bleed valve connected to the left front shock air line).

I started it, and it raised back up. I routed the air pressure valve into the car (taped it to the top of the steering column). Normally I would only have to drive a couple of miles at freeway speeds before it would drop and I'd get the air suspension error. It was 48, and I drove a total of about 20 miles round trip, but I never got low or got an air suspension error. The lowest it got was about 105pie, but was at 115 most of the time. It was interesting to note how it fluctuated when going over bumps/dips (which makes sense). When I slowed down and was driving down the driveway, it had increased to around 135psi (which would make sense since it's supposed to be higher at low speeds).

I was very surprised I didn't get an error. I'm theorizing that the soapy water actually helped the bag seal on the top. That said the car has about 160k miles; so I'm thinking of replacing the front bag/dampers anyway. Just want to be absolutly sure that's where the leak is before I spend the money.

I will be getting a code reader that will pull all suspension codes this week, so will check that before I start ordering shocks.

BTW, I confirmed that it is only the front shocks that have the issue. The front will lower and I'll get the air suspension failure error, but it's only the front; the rears are fine (don't drop).

One quick question? Where's the air pump? I did do the rebuild, but I can't remember what side of the front it is. I thought it was on the right side, but at one point I heard a lot of air escaping, and it was coming from the left side.

Thanks,

Gordon

 

Air pump is in front of front left wheel, under the plastic inner fender.

 

It might well be that your ride and engine bay warming were enough to "close the top seals" of your air shocks/springs to avoid the cold-leaking issue.
I have noticed, before I finally decided to replace my front air shocks, that even though I could have the car low and the air suspension error when starting the engine at cold (and no joy even after the compressor tried unsuccessfully to rise the car), just waiting about 20 mns for the engine to warm up was sufficient to close the seals and allow the compressor to succeed in raising the car.
Of course that was a temporary fix only and I had finally to bite the bullet and purchase new air shocks...

 

Actually, the above is what used to happen. I'd get the error, but if I was only doing stop and go city driving, and shut it off once or twice, it would have warmed up enough. But it has gotten to the point that it might be okay in my garage over night, but once up to highway speeds (65-70 mph / 100kmh), it only takes a few minutes before the cool air blowing would cause the drop. And it used to be only when temps were lower than 50F/10C. Now it can be 65F/17C and it will happen at high speeds. So they are obviously getting worse quickly.

I do want to reconfirm with the new code reader I'm getting Thursday that is supposed to read all suspension codes, and then I'll order the replacement shocks.

Anyone have good luck with 'reasonably' prices replacements. I'm not going to put Blisteins on a car with 165k miles and transmission issues (that's for another thread)...

 

See the thread I just started regarding the Suncore units. First set I've installed so no time or miles on them yet, but Brewster411 posted with his experience.

Suncore Air Spring/Shock Absorber Installation Report

Cheers,

Don

 

Here is a thought from left field. When mine start to leak in that area - they do not yet - I am going to spritz that area with ATF (automatic transmission fluid).
"Why?" you ask. I have used it on seals for quite a while. My son's Corrado needed the power steering fluid filled every day. I ran out of the VW fluid so had to use something else on hand. My Alfa actually calls for ATF for the steering fluid. So the Corrado was filled with it. That was more than ten years ago and it has not needed refilling since! Just a note - I always use Amsoil full synthetic ATF and do not know if other ATFs will do the same.
When the leak happens I will give it a try and let you know.

 

That, as well as brake fluid, can soften old rubber.
Have used old brake fluid b4, on old, brittle, rubber, motorcycle parts.
Carb intake boots, that are no longer available, too stiff & brittle to fit well.
Will soften up so they can be reused, the shock seals might soften as well.
Just be very careful of the painted surfaces, if you try brake fluid on the top seals.

 

The brake fluid works well however, as you noted, the paint removal with the brake fluid is the main problem.