w220 airmatic leak + new clunking sound

[ItalianTuneUp]

2005 W220 S320CDI

After seeing car lowered in the mornings, I did some reading and then inspected the front strut seals. They were cracked.

Rather than buy new front struts, I bought 2 repair kits, one each for left and right. I also had the airmatic relay replaced.

MB fitted these, and I assumed all was well. However, the front is still low in the mornings, so it seems as though the repair has not worked. The car now seems to lower itself more quickly since the repair. Also, a new clunking sound has appeared.

I took some photos which I can post here, and it seems to me that the seals have not been made airtight, which would explain the low body.

The new clunking sound appears at low speeds on roads with bumps and uneven surfaces, and seems to coincide with the bumps in the road surface. On motorways the clunking sound seems to disappear, perhaps due to smoother road surface.

Any ideas?

Related to this airmatic issue, a few weeks back I had a very low speed impact to the rear whilst reversing. The effect of this seems to be that the next morning the rear was raised for the first time.

I suspect that the rear impact may have knocked a rear airmatic level sensor. In the morning sometimes the rear is raised, and sometimes lowered, just like the front.

I intend to take the car back to the MB dealership to see what they intend to do about the unsuccessful front strut seal repair, but any advice gratefully received.

I will post photos of the 'repaired' front strut seals tomorrow.

Once the door is opened and ignition started, the car self-levels, so it seems that the pump is ok. On motorways the ride seems ok, but may be not quite as smooth, but this might just be my perception. I also have the impression that the steering is more spongy since the front strut seal repair, requiring more correction than before the repair, and there seems to be more steering play.

Interestingly, as the visit to the MB workshop was the first one during my ownership, they did some kind of health check and I wonder if they were a little aggressive in testing things? I have a list of work items that they recommended, if it helps, and I can post this along with the strut seal photos.

 

[pc-uk007]

MB will b able to put a diagnostic test on your car to check for leaks why did they not do this at the first visit to them ???

health checks normally have traffic light indicator, red being serious

 

[ItalianTuneUp]

I'm not sure if they did an airmatic diagnostic check, but if they did, they didn't mention it.

Perhaps they just followed my request to fit the new strut seals and replace the relay?

I'll post the strut pics and see if anyone thinks the repair looks good or not.

 

[ItalianTuneUp]

Front strut seals after repair:





Note the areas directly under the brass air intakes on the sidewall where there is no epoxy. Am I right in assuming that this has not been fully sealed?

 

[ItalianTuneUp]

Bit more info on the second problem of the rear height in the mornings...
If I park on the level, then usually the rear is raised. If I park facing down a hill, the rear is lowered just like the front of the car.

As the rear only became raised after rear impact, I'm hoping this may be related to the rear level sensor linkage.
This thread seems interesting and could be the cause (see posts #6 to #10):
Rear Axel Level Sensor Airmatic - Mercedes-Benz Forum

So I need to find this linkage whilst the car is on a ramp and inspect it before exploring other avenues.

 

[ItalianTuneUp]

Looking at the invoice, it says "Front air suspension struts (2) at upper cover seal (after check)"

Perhaps the "after check" means that they checked for leaks? Or just a standard job description?

And on the "Visual Health Check" sheet it lists:
Steering/suspension: Torque strut bushes O/S worn/split

If this is the cause of the new clunking noise, all I can say is that it never made this noise before it went into the MB workshop.

After a little search I found references to clunking sounds listed as likely to be either ball joints or subframe bushings (bushes?):
03 e500 airmatic - MBWorld.org Forums

 

[ItalianTuneUp]

Today I sprayed soapy water onto the strut tops, pushed the airmatic raise button and then checked for bubbles appearing, but I didn't see any, so perhaps the struts are not leaking air?

If this is the case then the leak must be elsewhere, and from some merc airmatic threads I read, it would appear that the airmatic valve block looks like the most likely culprit, based on the fact that all four corners drop. I will post the link when I find it.

 

[Dieselman]

Drive the car into a swimming pool and look for bubbles.

 

[ItalianTuneUp]

http://m.mbworld.org/forums/showthread.php?p=2967154&styleid=18

http://www.benzworld.org/forums/w220.-s-class/1329314-s-class-airmatic-woes-yes-again.html

From this last link, the valve block looks likely to be the cause of the symmetrical drop overnight.

 

[ItalianTuneUp]

Yes, from that last link, eric242340 says "Valve block on top of compressor failure (very common)"

But it would appear that chucking the car onto MB Star diagnostics to check for leaks first might be the smart first move to avoid shelling out on unnecessary parts. Hopefully it will show where a leak is occurring, but perhaps not.

One other possibility is a leak in a common tube that feeds both front and rear struts.
I also find it interesting that the car seems to lower more quickly now that the front struts are now repaired, in theory. The front struts were cracked and almost certainly leaking anyway, so I've done the right thing in getting them repaired.

This last post on that link looks interesting too, for other leak sources:

"...a leak in the air lines between the reservoir, a leak in the reservoir, the air line to the airmatic pump, or the pump itself are also failure points that could cause a symmetrical drop in suspension ride height. I discussed this symmetrical drop with a MB service guy and he told me that if the valve block were the cause for the difficulty to raise the vehicle, the car would drop all the way down over night and not just about a quarter of an inch."

 

[ItalianTuneUp]

This thread seems pretty good too:
Airmatic system continues to leak - help appreciated - MBWorld.org Forums

Post #6 there seems pretty comprehensive:

"Is your entire vehicle ( all 4 corners ) dropping overnight?
If yes, then your leak has to be upstream of the main manifold
which I believe is near your compressor.

the piping should be divided into 3 sections. rear, front rt and front left.
because this is how your transducers are wired.

If you check the area that is common to all four corners this will eliminate
a lot of wasted testing.

This area would be at the compressor, the main reservoir, the main manifold, or any of the relative hose connections.

Since this is a slow leak, it may be harder to trace, but there is always a way,it just may take a while but here goes...

Unless there is found to be an internal leak at the compressor, I would eliminate this..

to find out if the compressor or the dump valve is leaking, find the dump section where the compressor depletes the air after going into rest mode.

You know when you get out of the car after after driving and you hear a whiiish of air when you lock the car. find this connection and make sure that once this air releases it stops.This should be a solenoid valve that has a hose connected to one side and goes to ambient air on the other. It may still be seeping and you not be able to hear it.. this will slowly drain all of the air from your system and it will not come back up till you unlock the drivers door and restart the car.

The reason your compressor doesn't start back up and try to pump up the system is because it is in rest mode.

This may be the culprit..

is this what you are experiencing?

That is one possibility.. the other which is much easier is to go from the compressor to the main manifold checking all hoses for slow leaks including the manifold.

To do this.. start the car, and raise it using the raise button. then shut the car off but don't lock it. In fact, I think you have to leave the drivers door open so that it will not go into rest mode. with the car naturally raised, you can use a light soap solution to spray the components and check for bubbles.. this is the most effective way to find small air leaks in tubing and pneumatic components.

With the front lower cover removed, you should have access to most of your pneumatic components..just keep a block or two under the frame for safety but not supporting the car.

Of course if you are only talking abou one wheel, then you just need to find out which hose goes to that wheel of its the front or in case of the rear, take a look at the distribution block in the back of the car where it tees of for the rear wheels."

Seems like I didn't shut the ignition off after car raised when I checked for leaks with soapy water so I probably need to retest again, and have the car on the level when doing it.

 

[ItalianTuneUp]

So, I think my plan of action for treating these three issues is:

1. All four corners dropping overnight due to air leak:
a. retest for air leaks using soapy water sprayed onto front strut seals according to info above
b. if leaks from front struts are present, get MB to fix the repair
c. if no leaks are found in front struts then get a leak diagnosis done on Star system and go from there
d. so far, the most likely culprit is probably the valve block on top of the compressor

2. New clunking sound:
a. query what MB did as part of their health checks to see if they did something that could have caused this
b. research this more, but could be torque struts bushes, ball joints, or some other similar related components (ask V12)

3. Rear raising overnight when parked on flat road:
a. check rear level sensor linkage for damage and replace linkage if necessary (part #: A 220 320 00 32 ?)
(http://www.benzworld.org/forums/w22...r-axel-level-sensor-airmatic.html#post4867490)

 

[ItalianTuneUp]

Hah, ECP ad on this page related to "steering play" mentions wheel bearings:

"Over time, wheel bearings suffer the effects of wear and tear. Water in particular takes its toll on them, making then rust or spoiling the grease that surrounds them.

Wheel bearings allow your wheels to turn smoothly and also support the weight of the vehicle. If you're noticing alignment problems, your wheels are making a rumbling sound or the steering seems to have too much 'play' then you may have a wheel bearing problem and they may not be doing their job correctly. For quality wheel bearings for any car, check on line at eurocarparts.com and head off the danger of serious damage before it's too late.

Didn't know that wheel bearings could affect steering play???

 

[grober]

You sound to have most things covered. Make sure conditions are the same as when the fault occurs engine running etc. Might be helpful to get a hefty assistant to " bounce " the rear end [ engine running- car warmed up] while you try to locate the source of the noise?

 

[ItalianTuneUp]

Thanks grober. From all the reading I've done to try and nail these problems down, it appears that the 'rear raised' issue is very likely to be the rear level sensor linkage is worn/corroded/damaged, as apparently failure of rear struts are fairly uncommon due to the stable temperature environment they're in, unlike the front ones housed within the hot engine compartment. I'm amazed that MB didn't issue a recall on front strut seals, as this appears to be a common issue.

And from reading tales from other people who have experienced the same rear raised issue, it seems that it occurs after rear impact or a seriously big bump in the road. Presumably this shock is enough to cause the linkage to fail when it is about to go...the last straw.

I'll post back on progress with these jobs. I'm feeling much more confident that I can nail each and every one of these gremlins now after reading through reams of forum posts.

Now, I'm off to find a ramp...

 

[V12]

Looks like you have a reasonable plan together.

I'd guess that the rear end bump and the rear height is coincidental. I can't see how the impact can be transmitted down through the body and into the small link arm. It's worth checking as it's so easy to do when on a ramp but don't get too tied up with it.

I would look closely at the valve block personally, just a hunch.

As far as the knocking goes, it could literally be anything. To fit the new seals they will have had to remove the struts, this can involve removing the lower arm if the struts are being stubborn. In removing the lower arms it will disturb the ball joints and could have just tipped one over the edge.

Possibly due to the good cabin isolation, ball joint knocks go from nothing to very bad, very quickly. I got a knocking which started last week and jacked it up this morning to find it is the ball joint between lower arm and anti roll bar. Luckily for me I see that MB sell just the joint so with the help of a press, it'll be a cheap fix.

 

[ItalianTuneUp]

It looks like it is possible to do the front strut seal repair without removing the struts - see this, comment #11:
Airmatic Kit Replacement - Page 2 - Mercedes-Benz Forum

Here is the repair in action:
Mercedes-Benz W220 Strut Seal Tools In Action - YouTube

Interesting too:
W220 Airmatic suspsension and other points to watch - Mercedes-Benz Owners' Forums

 

[V12]

You learn something new every day!