NCTRNL

Quick history: had been getting intermittent airmatic "visit workshop" messages that were 5503 "Recovery time during filling of central reservoir is too long" codes. FF a few weeks, coming home get the "too low" message. Get home, front left is down.

Figured I would start with the compressor because that's what the 5503 code seems to be usually. Got a pump/relay from RMT yesterday and replaced it. When the car turns on and the compressor engages, you hear a rhythmic thump while the car is "inflating". You can see the wheel go up and stop every time the thump happens. It does this over and over for a few minutes then the compressor stops running and the wheel eventually settles back down low. There's no visible damage to the strut there.

After last night, now the passenger side front is down some too. Not as far, but noticeable.

A couple of things have me wondering:

1. when I put the air line back into the new compressor, the 10mm fitting around it just keeps turning. It never seems to stop. This isn't a new brass fitting, I re-used the fitting from the old compressor.

2. Could it be a bad valve block? The leak is obviously VERY fast, like it pumps up the wheel but once the compressor stops, it comes back down quickly.

kajtek1

When corners go down overnight - you have leak on the bag or valves so compressor is not a problem here.
For proper troubleshooting you need to monitor system pressure, but still spray bottle with soapy water can turn priceless.
The compression fitting turning around is not a good sign. Confirm it with spray of water.

NCTRNL

Is there any way to make the pump operate when I have the wheel off for access to the pump? Also, the side doesn't leak down overnight, it leaks immediately. The pump raises it up and when the pump stops operating, the side lowers immediately.

kajtek1

SD can activate the pump per my knowledge.
You can follow my topic about compressor rebuild where I ended up adding a Tee on the system, what allow me to put pressure gauge and then shop compressor for testing.
But with such big leak it should be pretty easy to narrow it down.

NCTRNL

Any idea why it would only inflate for a few seconds at a time? I remember it making a similar noise when I was moving the car to work on it with the old pump.

kajtek1

Your compressor can overcome the leak when it is working, so the leak can't be that big as that compressor is not having huge output.
But the compressor is protected from overheating by computer program that will time out and give it cooling period, so that is what you might observe.
Per my experience the time-out is 90 seconds and then about 5 minutes of cooling down. When 2 or 3 attempts will not keep the suspension up, you will get a warning.

NCTRNL

Yeah this is definitely not that long. It cycles for a few seconds on and off. I'm uploading a video where you can hear it cycling and you can even hear the leaking sound. I'll post it in a second.

NCTRNL

Here's the video. Every time you hear the click, the car raises a little bit and stops. Then it raises again with the click. Over and over.

Yuille36

I think that you may have a blown air strut, the air struts actually have a air bag built into them. The rubber airbag does fail, when they get a tiny hole in them. When the air compressor kicks on, the airbag starts to unfold as air is pumped in, once the air finds the tiny hole it quickly leaks out, thereby causes the car to drop.

BryanW203

You do know you have a friend that owns the exact same car and used to work for Mercedes.

NCTRNL

Ha...I really felt like I would be bothering you too much...

NCTRNL

OK I have Arnotts on the way for both front struts. I have to replace one of the drive axles and do a brake job while I'm in there. Which bushings and things should I take care of while everything is apart?

kajtek1

If you really want to go that far - I experienced that hydro-bushings on control arms are short-lived and hard to pinpoint when they go bad.
Front only cost in $30's but take some labor.

NCTRNL

So we've had some fun times. To update, finally got the front two struts out. Left was definitely blown and relatively easy to get out but that axle was already bad so it needed to be replaced. Got the other side out and destroyed that axle in the process. Getting both axles out wasn't fun but I got them out.

FF to yesterday. Two replacement axles and two arnott struts that showed up yesterday. Working on the left side, finally got the axle in, then figured out how to get some air out of the strut by plugging it into the car and using my MB II (Arnott was definitely no help there.)

Got everything in, a bolt through the bottom of the strut into the control arm, both sides of axle in their respective places. Was putting bolts on the top of the strut when I noticed the Voss air line connection looked...interesting. It was at an angle and I thought "well maybe Arnott figured out that this configuration works a bit better than stock". Famous last words. Went to insert the air line and the fitting just came out of the strut. F#*K! Tried to reinsert it, thread it, nothing worked. Called Arnott right before they closed and they told me the whole strut had to be replaced. So I had to pull the strut BACK OUT, pack it up, get it to FedEx so they would ship me another one. Good lord.

NCTRNL

Welp, RockAuto now informs me that the one they said they had in stock apparently does not exist. Now trying to find another Arnott AS-2295 strut somewhere. Going to call Arnott and see if I can just send them mine and have them rebuild it.

kajtek1

I feel for you, but on other hand my late friend was owner of German Auto and he told me lot of such stories.
He took the car apart and order left door. The only source -dealer took 3 weeks to deliver ... right door.
Shop space is not coming free, but he couldn't pass the 6 weeks of storage to customer who was paying for door replacement if you feel the trend.
Good for you you can park the car and take the other for commute.