Bouncy rear on ABC
Thread Starter
Newbie
Joined: Jul 2019
Posts: 13
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From: Sofia
W220 S500
Bouncy rear on ABC
I documented replacement of the rear struts on my other thread, but wanted to put this issue on a separate one. I started noticing the car being bouncy on the highway last month, it would go up and down uncomfortably so. I dismissed it due to our not so good roads, but now when i took it to the shop for brake fluid i pressed down on the rear and it was basically a bouncy castle. The front end was solid though, didn't move. Now a few notes before I recieve tips and info on this issue: this is a '03 S500 with the ABC option, i replaced the original rear pair which was leaking with a used AMG pair, since non amg are rare here. I was worried that they would not communicate properly with the rest of the system, but it raises fine, there are no external leaks, the pressure is good, oil is ok. If i raise then lower the car the rear is solid as it should be for a moment before losing rigidity. This leads my slighly informed mind to two conlcusions: I've been sold bad struts which i didn't properly check for the life of me or the rear valve block need repalcement/cleaning. Should i get it readjusted somehow with STAR or is that not a thing? and to be honest i havent done a rodeo, i just cycled the height ~20 times to regain pressure after the replacement. Any ideas? I'll ask around the local shops and friends in the mean time
P. S. The rear does sit lower than the front from the side and from the rear looks like its also sagging to the left.
P. S. The rear does sit lower than the front from the side and from the rear looks like its also sagging to the left.
Last edited by Pavel.A.; Nov 18, 2019 at 09:27 AM.
Thread Starter
Newbie
Joined: Jul 2019
Posts: 13
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From: Sofia
W220 S500
That's the thing, no constant errors on the dash and the STAR system. If there were, it'd be a lot easier to fix. Only time I've gotten an error for "car too low" is when i park on a big incline where the front was on a ramp and the rear was close to level ground. And the car behaves fine on the road, it absorbs bumps evenly, i dont feel it being softer in the rear except for the highway thing, but the road is not smooth enough to conclude anything. And p.s. to the previous post, the car evened out after driving out the garage
Last edited by Pavel.A.; Nov 18, 2019 at 01:39 PM.
Super Member
Joined: Dec 2007
Posts: 980
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2005 S500 Designo
Could be a valve block, but unlikely.
I have a similar issue, and I suspect it’s the level sensor. A STAR diagnostic might allow you to compare the levels between the two while bouncing the back up and down.
[edit]
Please report back
I have a similar issue, and I suspect it’s the level sensor. A STAR diagnostic might allow you to compare the levels between the two while bouncing the back up and down.
[edit]
Please report back
Thread Starter
Newbie
Joined: Jul 2019
Posts: 13
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From: Sofia
W220 S500
I thought about calling him, but when i went to get an alignment it was perfectly level on the sheet, so it problably was from the bad road angles i park it on. I'll call my guy to check it out just in case
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Mercedes
That's the thing, no constant errors on the dash and the STAR system. If there were, it'd be a lot easier to fix. Only time I've gotten an error for "car too low" is when i park on a big incline where the front was on a ramp and the rear was close to level ground. And the car behaves fine on the road, it absorbs bumps evenly, i dont feel it being softer in the rear except for the highway thing, but the road is not smooth enough to conclude anything. And p.s. to the previous post, the car evened out after driving out the garage
What you described sound exactly like bad accumulators
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Senior Member
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S55 AMG
Its your accumulators
Don't even try wasting your time diagnosing/changing anything else
The typical ABC protocols are:
Sagging? Valve blocks
Bouncing? Accumulators
Car is slammed and won't go up? Bad pump, low fluid, or ruptured lines
It's really that simple
A faulty level sensor will never cause bouncing. I've had a faulty rear right strut travel sensor for the past 5 years and all it does is not allow you to change your ride height with the dash button.
Don't even try wasting your time diagnosing/changing anything else
The typical ABC protocols are:
Sagging? Valve blocks
Bouncing? Accumulators
Car is slammed and won't go up? Bad pump, low fluid, or ruptured lines
It's really that simple
A faulty level sensor will never cause bouncing. I've had a faulty rear right strut travel sensor for the past 5 years and all it does is not allow you to change your ride height with the dash button.
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Mercedes
you keep talking about constant errors , Not answering the question. A bad accumulator shows a Brief millisecond red warning error on the dash when going over a bump in the road at speed
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From: Montreal, Quebec
2009 E350 4M Avantgarde;mistress 2002 S600; wife 2014 C300 4M
One way to check the strut accumulators is with the old "bounce" test for shocks on other cars.
If you can make the corners bounce and then it dampens, the the accumulator is ok.(engine not running).
If you can make the corners bounce and then it dampens, the the accumulator is ok.(engine not running).
Thread Starter
Newbie
Joined: Jul 2019
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From: Sofia
W220 S500
Do you get brief red ABC warning flash on the dash when gojng over bump or not ? If you do , it’s your accumulators
you keep talking about constant errors , Not answering the question. A bad accumulator shows a Brief millisecond red warning error on the dash when going over a bump in the road at speed
you keep talking about constant errors , Not answering the question. A bad accumulator shows a Brief millisecond red warning error on the dash when going over a bump in the road at speed
Thanks AlexMercedes for the simple answer! I assume both accumulators are identical, so I'll get one + a pulsation dampener, because I've been postponing that for some time anyway. I've checked and dampeners are not in stock here, so i gotta order one. In any case see ya next month guys!
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2005 S500 Designo
I was under the impression the valves shut when he engine is off, thus bypassing the accumulators
