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.

 

IT could possibly be a problem with your accumulator(s). Any red warning lights flashing on the dash when going over railroad tracks?

 

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

 

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 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

 

An accumulator does not give a constant error , it gives a brief red flash on the cluster when going over a. Bump at speed - so fast of a flash you can barely see it on the dash cluster .

What you described sound exactly like bad accumulators

 

How could i test them? Is there a surefire way to tell, so i don't end up 400$ deep for nothing?

 

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.

 

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

 

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).

 

No errors pop up over bumps. And for the record, when my front one was blown open I still had no errors, not even on STAR. There were none until all the fluid was gone. Then it was kinda obvious what happened

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!

 

Are you sure?

I was under the impression the valves shut when he engine is off, thus bypassing the accumulators