Ohmann

Ladies and Gentlemen
2 years ago, I rebuilt suspension 100k miles, new pump, rebuilt valve blocks and replaced black bladders except for the small return in the rear.
Could not have done this work without this forum. Let me say that initially I put in rebuilt pump, This was a mistake. Rebuilt just provided practice for removal and install of new pump. Twice, I might add. Highly recommend new pump when the job is difficult enough without needing practice.
Now my drivers side settles within an hour after parking. It perks right back after start.
Would the front or rear valve block be the cause of car dropping on entire left side?
Thank you all for suggestions

thias

I would think you have two separate problems. But wait for the pro's to confirm.

sivikvtec

Both front and rear valve blocks have a problem if one whole side of the car is sagging.

The front block is for the front wheels and the rear block is for the rear wheels.

sivikvtec

Also, if you raise the car to full height AFTER putting it in park I bet the amount of sagging will be drastically reduced.

seven_out

When the chassis drops at a corner there is a presumption that the strut's valves have an internal leak. But at two corners? Now I think you have to consider possibilities which would otherwise seem very remote.

It's plausible to me albeit highly unlikely that the ABC controller may have a pair of faulty outputs which are opening the strut valves very slightly. To eliminate this as a possible cause, when you shut the motor off I would disconnect the rear battery and observe what effect this has on the lowering.

Ohmann

Thank you guys
i raised height to two dots, shut car off and disconnected rear battery
Will have results in the morning
These cars are so temperamental, it’s like being married
I love it
thanks

matk

Why would that make a difference? I would have thought that a valve block issue will carry on dropping that side of the car?

Ohmann

Alas, with car in the 2 dot position and rear battery disconnected the car maintained position over night. This morning reconnected battery, reset turning wheels, lowered to driving position, will let it sit 3/4 hours to see if it sits
if it does maintain height then it must be electrical Wow! Will check after lunch
thank you!!

sivikvtec

Based on my experience that test might give false results.

I recommend driving it around the block at normal height, parking it, and then disconnecting the battery if you think it’s electrical.

I’m sure the car will still sag badly, I don’t even think the ABC control unit gets power from the trunk battery lol.

sivikvtec

I have no idea how/why it works. But it does.

I had my valve blocks rebuilt by a well known vendor and still have the problem. The vendor believes that dirt/contamination are in the valves causing the malfunction. My ABC pump died, so maybe it was sending metal particles into the system as it failed. A full fluid flush and rodeo didn’t fix the problem.

Next step will be to take the valve blocks out again (ugh) and disassemble the lock valves to clear any debris. In the meantime I am usually OK if I park at full height.

One theory of mine is that when you park and raise the car, fresh fluid is sent through the lock valves and reduces the debris trapped inside, which allows each valve to seal better when it closes.

Ohmann

Car has maintaining posture all day, which it was not doing before battery disconnect
i am going for a drive out on the interstate and see what happens tonite after putting it away
Thank You
only another owner can understand this cars many nuances

sivikvtec

Any update?

Ohmann

Yes
Since reset car has maintened posture
White ABC light appeared and the button to raise and lower has quit working as it did before reset
Really need a diagnostic done so I know what is going on
A month ago I had my roof hydraulics repaired because of the front roof cylinder leaking. 6 cylinders were replaced at CabrioletHydraulics in Bremerton Fl. Great job!! While I was down there for a winter break.
Never had a leaky trunk before front cylinder went bad. The two pumps at the bottom of the trunk have been acting funny. Lumbar support cycling on and off occasionally. Trunk is dry again now. Gonna get down there and clean up pumps soon.
So yesterday I changed the spark plugs
Tommorrow changing voltage regulator behind the alternator.
Will get back to figuring out ABC soon
Thought I was going to have to rebuild those two valves again. Now I’m pretty sure it’s something else
Simple I’m sure
What a Car!!
Thank you for your help
I love this forum
Learned so much

Seven Out

For probably less than you'd pay a shop for a diagnostic you could do one for yourself. For about $135 you can get a Foxwell scanner that is reviewed in a sticky. Or if you prefer to look at a laptop screen instead of a little 4" screen, then for $250 you can duplicate a Mercedes tech's workstation (Star Diagnosis).

seven_out

If you are still raising the suspension before shutting-off the engine, then this is somehow the cause of your suspension maintaining height, I believe. The idea behind disconnecting the battery was not to reset the controller, but instead was to disable any leakage currents from the controller which perhaps in theory could cause the suspension to move overnight -- a notion that I believe I mentioned seems implausible to me but worth investigating. If this helped, it's benefit ought to have been lost once you quit disconnecting the battery.

You may be able to suss the cause of your ABC fault indication by correlating its appearance with specific events; e.g., starting the engine, traversing potholes or bumps.

matk

I can’t help but feel you should just overhaul the valve blocks. It’s useful preventative stuff regardless. When I had mine done the state of the seals was shocking. I’d also renew the fluid and change filter. Then see where you go from there? You can spend ages chasing electrical stuff, but without good diagnostics you might struggle to identify the problem or it may not even be electrical.

Do the mechanical stuff (valve blocks) there’s no doubt about that side then and you don’t need diagnostics. If it doesn’t fix it, then nothing lost but you’ve ruled out that side of things definitively. If you carry on chasing electrical stuff at this point there’s an element of uncertainty (intermittent fault?) and guesswork involved.

Ohmann

Thank You! Since I have some time it may be wise to rebuild valve blocks again. New pump and valve block rebuild was done 20k miles ago with new Corteco black *****
i have flushed hydraulic fluid regularly 20/30k miles . Car has 120k miles 2003. Bought it with 30k miles 7/8 years ago. Should have them sent out for professional rebuild.
one seal in each block is not holding a seal. I’ll get a good look pulling them out. Appreciate your help.

sean65

If you're not seeing fluid leaking, then the fluid is getting past the solenoids in the valve blocks when the car is sitting. If the fluid is getting past the solenoids, and both ends are sinking, you most likely have issues with the o-rings in both valve blocks. It does seem odd that both would fail at the exact same time. Was one end drooping before the other? I'm not sure what the electrical would have to do with this (given my somewhat limited knowledge of the system). Raising the car to the top position wouldn't remove the issue, it's still a locking position problem at the solenoid in the valve block.

sivikvtec

I had this problem and reduced the amount of sagging by parking at full height.

The original poster tried the same and was successful.

sean65

Ok, what I'm saying is it's masking the problem, not fixing it. I'm not an ABC expert but if the fluid is getting past the solenoids and pushing back into the reservoir it's generally due to bad o-rings. What I don't know is if raising to the top position is placing a different set of o-rings as the locking position. Could be.

sivikvtec

100% agree that it only masks the problem.

I had my valve blocks rebuilt by a reputable vendor and the problem persists. Assuming the quality of the rebuild can be trusted, the sagging is happening because the lock valve cannot close completely due to debris trapped in the system.

matk

Or alternatively the blocks weren’t rebuilt correctly, it’s quite easy to not seat one of the seals correctly. Also it’s very advisable to do an ABC fluid and filter change at same time for precisely this reason. Did you get a fluid and filter change done same time?

sivikvtec

Full ABC fluid flush, filter change, magnetic filter added, and another rodeo afterwards.

The vendor that rebuilt the valve blocks says I need to flush fluid at each bleed screw to get the debris out. I’m trying that next. If it fails, I’ll take one of the valve blocks apart and inspect it.

Ohmann

Did not know there is a bleed screw to flush some fluid
would like to try that as well before removing valve blocks
a friend of mine represents a German co that makes precision
orings and gaskets for many industrial uses to include nuclear power plants
He and his boss wanted to rebuild my valve blocks
I am guessing one o ring on each block isn’t quite right
would love it if flushing some debris would work
Thank You

sean65

No, it's 32 o-rings across the 4 different solenoids: https://www.diybenzrepair.com/reseal...e-block-reseal