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Discussion Starter #1
2005 S55 AMG rear side ( rear both wheels) started sagging when parked for a week or less from few weeks ago.
After searching forum I realized that the rear valve could be a problem. So, yesterday I removed the rear valve black and checked. It was completely cleaned and o-rings were very good condition. So I reassembled and re-installed. So, I do not think the valve block has problem.
I will wait few days if it still sags. There is no leak at all anywhere and from Xentry system it shows pressure steady 185-190.

Does the rear accumulator also make sag when if fails ? I do not have any warning sign when run over bump at all.
Could you advise me what else I need to check?

Sun
 

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Discussion Starter #3
This condition is considered normal and is covered under the attached Dealer Technical Bulletin (DTB).

Bob
Thanks for sharing info.
It's been 1 1/2 days after cleaning valve block. Now rear driver side is still maintaining good height ( last week both side dropped ) but rear passenger side completely dropped. I did not replaced o'rings when cleaned cause it looked all good shape. I will remove and clean again and replace o'rings this time with new accumulator ordered today.
 

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Discussion Starter #4
Update!

I removed the ABC valve block and checked again, specailly shut-off valve. It was completely cleaned and no dirt at. So, I replaced all o'rings using purchased from this site below.
Also, I removed checked rear pressure accumulator. It looked liked perfect condition. I inserted a screw driver into the connection area and compared how deep it went. It was the same depth with the brand new one I purchased yesterday. Anyway this accumulator was the original aged about 11-12 years old and close to end of life, so i replaced.

Result!
Spent overnight with new orings, no signs of sagging at all.
New o'rings seal pretty good.

450 Piece O-ring Kit Buna-N 90 -003 to -020 [K450X18N90-003-020] : The O-Ring Store LLC, We make getting O-Rings easy!
 

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Love the thread! I have the same issue on the front of the car. I changed the o rings in the valve block as well, but the sag is still there.. I heard that the accumulators wouldn’t be the sole issue as to why the car is sagging so is there anything else I could try? I’m out of guesses..
 

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How long does it take to sag? Overnight = problem. Week or more = within normal limits.

My car takes about 4 weeks before it shows a sag, but I've rebuilt both valve blocks.
 

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How long does it take to sag? Overnight = problem. Week or more = within normal limits.

My car takes about 4 weeks before it shows a sag, but I've rebuilt both valve blocks.
It is permanently sagging. It used to sit up after I would put it into gear but now it won’t sit up at all.
 

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What does SDS tell you ?
It will likely get stupidly expensive without SDS as by using Guesswork and "Parts Darts" you may end up changing loads of bits you do not need to.
SDS is a must have (not other lesser machines), if you work on most post 1998 MB's ;)

It just might be a Height Sensor broken, disconnected mechanically, or out of range ;)

HTH,
 

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You have a different problem. This thread is about suspension bleeding down from normal height when the car is parked and not running. In that case, fluid is leaking internally to the valve block and allowing the strut to compress.

But your car rides at the wrong height with (Perhaps) good hydraulic pressure.

Time to read out the strut values and system parameters. You can only do this with STAR.

If the car stays low at that corner, even when running, it’s not a hydraulic leak issue, it’s a control system issue. You may have weak pump output, a bad sensor, a bad strut, bad internal strut sensor. Put the car on STAR, read out the ride height sensors, do the rodeo and see what’s not working.
 

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2005 SL65 plus 13 other non MB toys
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This has been "gold" for me! I have read and re-read this several times. Excellent resource to understanding ABC.

 

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Here is a quote from the above mentioned:

"In each wheel well you find a ride height sensor. It reports to the ABC control module how high the corner of the car is. If a corner of the car gets too low, an "ABC Car Too Low" message will appear on the dash.

Usually this message indicates a low pressure issue preventing the ABC system from keeping up with demand, but the sensor can go bad and give false information or no information to the control module. If you suspect one of these sensors is the problem, do a visual inspection to make sure the linkages are not damaged or loose. Also check the wiring connector to make sure is on tightly and the connection surfaces are not corroded. If you suspect the sensor is bad, you might try swapping it with one from one of the other wheel wells, and see if the problem moves."
 
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