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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG. 2011 BMW 335d
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Discussion Starter · #1 ·
@Dave2302 ....hope you have some insight on this.

I have a 2006 ML350 here, one airbag in rear and both air suspension in front were blown, customer elected that I replace shocks and airbags on all four corners, plus the compressor. (note: ML350 has the adaptive dampening system)

So that's what I did, I bought the rear airbags and all four shocks/airbags and swapped them. The car no longer lists to one side or anything. The ride height is perfect. I bought shocks from these guys...

Rebuild Master Tech Air Suspension, Engine Parts & More...

They have good rep and do good work.

There is one issue though...

The car ride quality is SO bad now! I literally feel every single pebble on the road, on a relatively smooth road, I'm the one bouncing on the seat, instead of the shocks! I've had smoother rides on a superkart with 2" of suspension travel at 110 MPH than than this ML350! It's ridiculous, I can't give the car back in this condition.

There's absolutely no codes in the car. None. Airmatic is squeaky clean (in both sense of the word, there is no water ingress on the module itself and theres no codes at all), all dampening valves actuate and work as they should, all level sensors are perfect, the car goes up and down on demand, compressor is brand new...

the only thing original to the car is the valve block...to my understanding, the valve block only regulates the air flow to individual airbags, it has no relation to the dampening.

Sport/comfort/auto button for the dampening doesn't do anything. They light up and change modes, but the ride quality is identical.

I see via my google fu that a bunch of people had this same problem, but they never posted the solution. Any ideas?!
 

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2002 Mercedes ML320, Mercedes 190E 2.3L (sold), 2001 Mercedes c320(gone)
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Maybe you should lower it a little, manually, using the DAS, could be something to do with shock quality vs height, just a little test.

Can you see if it's from all the wheels, ie test by puttin small bumps for individual tyres and driving over them.



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2012 GL 450 4Matic
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Did you reset the ride height on the vehicle? Typically when you replace a part you usually need to use Star to reset the ride height. From what I see on the website the air springs are all new, but the front struts are rebuilt. That shouldn’t be an issue because the dealers are installing rebuilt struts now too. The only thing that bothers me since they are selling these so cheap is what is the quality of the airbag itself? These are about 1/10th the price of new production Bilstein struts at 850.00 each.


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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG. 2011 BMW 335d
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8,321 Posts
Discussion Starter · #4 ·
I did not reset the ride height, according to DAS it is only needed if the calibration is incorrect, the airmatic computer has been replaced or level sensors have been replaced. It makes no mention of resetting ride height after replacing all shocks/airbags.

I already did the test, all four shocks that are apparently set to the maximum sportiness. I can literally jump on the car and the only thing flexes is the tires. The suspension barely moves, if at all.

I am considering unplugging all dampening valves, drive the car, and replug and hope it does the trick. Or reset the airmatic computer, or disconnect battery, or....

And yes, those shocks are cheap(er) than I thought. However, I was able to verify that the rebuilt shock they sent me is the original MB shocks, they also bore the same stamps and marking as the one I took off the car. Their black paint covers it, but it was visible enough that I could tell the shock was original and not a new chinese make.

The airbags on the shock, I'm not too worried about. My shop has used these guys for Lincoln and Dodge cars, and we have yet to have a come back due to their airbags. I would wager they are using the same airbag material on the MB as they do on Lincolns...and my customers abuse their Lincoln.
 

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2002 Mercedes ML320, Mercedes 190E 2.3L (sold), 2001 Mercedes c320(gone)
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I did not reset the ride height, according to DAS it is only needed if the calibration is incorrect, the airmatic computer has been replaced or level sensors have been replaced. It makes no mention of resetting ride height after replacing all shocks/airbags.

I already did the test, all four shocks that are apparently set to the maximum sportiness. I can literally jump on the car and the only thing flexes is the tires. The suspension barely moves, if at all.

I am considering unplugging all dampening valves, drive the car, and replug and hope it does the trick. Or reset the airmatic computer, or disconnect battery, or....

And yes, those shocks are cheap(er) than I thought. However, I was able to verify that the rebuilt shock they sent me is the original MB shocks, they also bore the same stamps and marking as the one I took off the car. Their black paint covers it, but it was visible enough that I could tell the shock was original and not a new chinese make.

The airbags on the shock, I'm not too worried about. My shop has used these guys for Lincoln and Dodge cars, and we have yet to have a come back due to their airbags. I would wager they are using the same airbag material on the MB as they do on Lincolns...and my customers abuse their Lincoln.
Ive little experience with this, but the one time i worked on an over sensitive set of air shocks assisting my mechamic friends, the problem was they were over pressured, a gl450 and it will clang and shake and bang on every bump.

Lowering it within the indicated green area in the DAS, brought it to normal. The car had a bad valve block so we set the height manually and unplugged the electrical connector.

Owner was cash trapped to do proper fix. Run the das, perform all pneumatic test, ensure the height is within the recommended green area. Wouldnt hurt to check.

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2002 Mercedes ML320, Mercedes 190E 2.3L (sold), 2001 Mercedes c320(gone)
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Ive little experience with this, but the one time i worked on an over sensitive set of air shocks assisting my mechamic friends, the problem was they were over pressured, a gl450 and it will clang and shake and bang on every bump.

Lowering it within the indicated green area in the DAS, brought it to normal. The car had a bad valve block so we set the height manually and unplugged the electrical connector.

Owner was cash trapped to do proper fix. Run the das, perform all pneumatic test, ensure the height is within the recommended green area. Wouldnt hurt to check.

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Theres other bits and pieces around this story though, like 2 air shocks busted like guns and brought the neighbors out. The air pump etc were then sending excessive air i would say, to the shocks and they would rise too high and one shock, front right, busted twice. Any attempt to drive at this height was extremely funny and unstable.

Once lowered the car drove smooth and has been in use without complains for about 3 months now, although the system has no control, more like a manually preset height.

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG. 2011 BMW 335d
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8,321 Posts
Discussion Starter · #8 ·
Hmmmmm.....that sounds plausible. I will investigate.

Maybe I will need to do an initial start and go from there.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG. 2011 BMW 335d
Joined
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8,321 Posts
Discussion Starter · #9 ·
Wanted to close the thread.... the problem was with the valve block. Even though the valve block passed all SDS test, it must've been defective internally. Replaced the valve block, and suddenly the ride quality is much improved. I can actually hit speed bumps at speed and not worry about conking my head on the roof!

The customer is SO happy now, as am I. This car has been in my shop for the past month... so much headache.

You can actually tell the difference between sport/comfort in ride quality now.
 

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2002 Mercedes ML320, Mercedes 190E 2.3L (sold), 2001 Mercedes c320(gone)
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1,458 Posts
Wanted to close the thread.... the problem was with the valve block. Even though the valve block passed all SDS test, it must've been defective internally. Replaced the valve block, and suddenly the ride quality is much improved. I can actually hit speed bumps at speed and not worry about conking my head on the roof!

The customer is SO happy now, as am I. This car has been in my shop for the past month... so much headache.

You can actually tell the difference between sport/comfort in ride quality now.


Aha! It's actually the most common issue. Good job!

My mechanic friends just had one again, an R350, car would not even rise at all, no leaks seen anywhere, SDS won't even actuate the pump for testing.

We actuated the pump and valve block, manually raised the car to a reasonable height and it stayed with the valve block unplugged. Meanwhile raising it with the valve block plugged, it only took a few minutes for it to drop, internally the valve block was letting air out to the tank I believe.

Customer will plan for new pump and valve block


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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG. 2011 BMW 335d
Joined
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8,321 Posts
Discussion Starter · #11 ·
Problem was definitely the bad valve block..I dissected it and ohm'ed the sensor that measures the strut pressures...it was reading significantly higher than a brand new valve block. So my hypothesis is that even though the valve block was only reporting 4-5 bar in each strut, it was overpressurizing the struts to the point where the ride quality was as hard as a rock.

The old struts had holes blown in the lining, likely as a result of overpressurization and car hitting a pothole, which cause it to blow.
 
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