Hary Gahtoe

I've got an unusual situation in the ABC. Also, No matching ABC searches found

I'm not even sure an MB SDS would work but I'm looking for answers if I can fix this myself.
Started 1 yr ago to settle slightly on Passenger Front. No Codes at all
04 SL500 92k
Front Valve block replaced
Front Accumulator replace
Full flush x2 w/filters and new fluids
Ran great for 500 mi.
Now it loses pressure up front after 2 days and after driving 2 blocks gets a visit workshop malfunction. But the minute I stop the car and cycle thru the ignition it's back to pressure without a malfunction code showing ever happened.
No leaks but here's the odd part. Fluid level engine off; Full. Fluid level running; Low by about 20-25%. I filled while running and it overflowed the tank at shutoff

If someone knows a solid diagnosis method how I can verify whats wrong I'm listening. I suspect several different things while nothing ties electrical to a negative running fluid level and a ghost error code that resets
If someone also has recently bought a new SDS I'd like to hear how your system works
Thanks

Cool R230

When you say "no codes" does that mean that you have connected it to a SDS and there are no codes under the Chassis, ABC section? In my case the warning has always set a fault code. They sometimes stack up, so it may help to clear the codes, drive it till you get a warning and re-scan.
Was the replacement valve block a new unit? The o-rings are noted for eroding and leaking internally.
Not surprised about the fluctuation on the fluid level, when the pump pressurizes the accumulators it takes a volume of oil to compress the gas behind the diaphragm. You just need to be sure that you are not leaking oil somewhere outside the system. Check the floor as the belly pans cover everything on the bottom of the car.
So it comes down to diagnosis...the SDS is the only good option as it is related to a sensor.

moretech

If there truly is no fluid leak it seems that the only thing it could be is a weak but not ruptured diaphragm. I guess that seems really weird but since the fluid is ok when the pump is off but low when running I cannot imagine anything else. let us know how this turns out.
moretech

Hary Gahtoe

Car in its present condition hasn't been SDS read.
Valveblock definetly worked and I got it rebuilt from a forum member.

About the Hydraulic fluid. The wrinkle is the "running" fluid level is out of whack.
Trying to correct the running level I overfilled the tank and it ran down the engine compartment after shutoff.
So with the fluid level set at full mark "Unbeladen" Shut the car off, wait a couple minutes and (even though running level showed low) the static (motor off ) level is right where it should be. I have paint paper under the car and no leak stain

But here's my SDS dilemma. IF it's an Accumulator or Valveblock pressure loss will it be specific enough or would the SDS only show pressure loss in total?
Also if anyone even have had low running fluid level diagnosis and repairs please reply
Thanks for the replies moretech & Cool

mbwolf

Hi
In general the ABC does not through codes if it feels not right. It only comments if something is really wrong. (Pressure, level)
Your problem is pretty easy to diagnose. Your pulsation damper is shot and needs to be replaced as well as the rear accumulator and return line accumulator. If replaced your level issues will be history. Important: Check your hoses at the same time . Your hoses are 12 years old and the typical life is 10 years +. The hoses will have to be replaced too. I just learned the lesson the hard way. A local hydraulic shop will be able to replace the hoses with 5000 psi hose for a quarter Mercedes would charge for the material. The expansion hose can be refurbished as well. Good luck !!

Hary Gahtoe

Thanks for the reply!
Congrats. I'm glad you were able to fix your car.
It might help if can I ask how you reached your repair diagnosis. What were you able to find that made it evident?
I have the factory R230 service repair CD but it is doesn't describe my issues to pinpoint a specific issue I'm experiencing
R230 ABC is daunting in HOW to diagnose and What actually causes some types system failures in detail enough to
My situation is daunting to diagnose because it acts like a hydraulics pressure issue but Error codes and all symptoms temporarily disappear by merely cycling the ignition

moretech

I agree with mbwolf above. With the age and mileage of your car it is most likely the various accumulators etc; that are causing the strange problem you have. They all need to go and you need new ones. Something just not right with one or more of them. Keep us posted as this is a very good learning topic for all of us. The very best to you!


moretech

mbwolf

Hi again
The ABC system is actually a pretty simple hydraulic system ( except for the ABC pump , the electronics and the way DB routed the ABC lines )
The accumulators work like a shock absorber in this hydraulic system. They dampen hydraulic vibrations and volume expansion due to temperature. These accumulators are not failing slowly. They work or have failed. Hydraulic fluid can not be compressed therefore if these accumulators are failing the bladder is deflated and there is no place for the oil to go when it expands except for overflow. When the system cools down the oil level will be low again. One of the first indication of failed accumulators is a short red visit workshop message when you hit a bump. The pressure in the system will spike because there is no space for the fluid to go and will trigger an over pressure alarm. The hoses in this system are the only expandable media left in in this system if accumulators have failed and the life of hoses will be exponentially shorted by failed accumulators.
If you can do the repairs by yourself you will spend about $600 in accumulators and about $200 -$300 to refurbish ALL your hoses. In total it took me about 15 hours .

Good luck!

Hary Gahtoe

Thank you mbwolf.

When I flushed the ABC, replaced the front block and the Accumulator. Ran for a month and now I got a car that shuts off the suspension in a couple blocks but has never gave red error msg.
Does someone knows if an MB C4 SDS will be able to pinpoint hydraulic pressure loss or sensors associated with the rear valveblock, Accumulator, PSS?
Point worth mentioning is the rearend doesn't lose pressure or angle but when the dash shows an ABC msg. the raise/lower ABC button won't work
Guess I am in the market for an SDS if anyone if finshed with one or has one FS.
Thanks

mbwolf

Hary
The system has 4! accumulators (1 front, one pulsation damper, one rear and one return). The return and pulsation damper are in the same circuit. If any one is deflated you will have issues since it will shock the whole system. The locking of the blocks is either caused by low pressue or low fluid level (suction pressure to pump). The SDS system, at least to my knowledge will not show individual pressure loss, only pressure loss over the hole system The valve blocks are not instrumented for differential pressue because no need.).
You need a SDS (bought a C4 for $400 in China + Dell laptop $100) to figure out if the malfunction of raising or lowering is a hardware or CamBus issue. In my experience it can be caused by a grounding issue of the Canbus connectors in the front left footwell. Indication was : ("Display Malfuncion, Visit Workshop") in white. Cleaning did the trick.

Hary Gahtoe

Thank you for the info.
I'm grateful for the positive response. My focus is diagnosing a faulty system and pass on hopefully very useful info

Welwynnick

The ABC fluid reservoir is only supposed to be full when the engine has been off for a while. It goes down when the engine is running. If it doesn't, the accumulators have failed. See below.

If it sags in one corner, it's not that serious; there's probably crap in the valve block.

Nick

Hary Gahtoe

I don't have sag and pressure loss is nominal
ABC tank has two sets of fluid levels.
Yes the reservoir level does drop from the full while engine off levels. ABC tank has two sets of fluid levels.The ABC reservoir cap has 2 sets of levels on the attached metering rod. Meaning that both levels must be within tolerances and lower level markings (while running at operating temps) should be the the most critical of the two settings. Which in our R230 tenatively suggests a loss in volume common to Accumulators and dampner. I won't know for sure until I plug in the SDS
Thanks Nick
Hary

Hary Gahtoe

The learning curve with a C4 is adding time to a full cure in my situtation. My initial setup revealed 3 SBC settings needed to reset. There was no driver display info at all. The C4 diagnostic display wasn't a malfunction, strictly a service reset
So with that done, reading the ABC pressure values at all 4 corners shows above nominal values and no drops after shutoff within 5 min.
Next step will be a test drive and process any codes that surface. According to the SDS readout the car (sitting, not moving) has no ABC error codes.

Hary Gahtoe

Hydraulics are not an ABC recordable data issue as per C4 DSD system.
I'm going back to internal leaks and parts that fail.

Heatwave

Question for Hary Gahtoe regarding C4 SDS: do you use SDS with the ignition key in the ON position and the engine off, or do you start the car and let it idle while using SDS? If you don't start the engine, do you put a battery tender on the battery to keep it fully charged while SDS is in use? Just wondering how you manage battery power during SDS use.

Hary Gahtoe

To check ABC pressure values engine needs to running.
But just for Error Codes you can leave the ignition in the on position which takes only a couple minutes.
There's a section in the ABC group that allows you to lower your car simply by adjusting the voltage values of each strut which is a bonus considering the hassle of installing lowering links

Hary Gahtoe

Blocks, Accumulators etc. won't but the SDS does read each strut though.

It's uncanny you mentioned the Canbus issue. I had a drivers footwell error issue I discounted as leaving the door opened while I was using the SDS. I am looking into this
Thank you for sharing what you found

Hary Gahtoe

Update
Using an SDS C4 I was able to reset all my updates and perform an ABC rodeo.
I'm now enjoying a car that rides and behaves properly. No error codes.

As an interesting side note; I was able to use the SDS to lower the cars ride height and it's quite low. But at any time I can change the values and have it back to original just by using the laptop.

next2pool

Where in the SDS menu did you find a way to adjust the ride height? I have been looking for that and you are the first one that has mentioned it here.

Hary Gahtoe

Diagnostic > ABC > level calibration

Hary Gahtoe

Screen shot of SDS thru ABC down to calibration

photo was of SDS didn't work

next2pool

Thanks for that. I think I've been in that part of the menu, but it requested level readouts from an electronic level. This looks almost like an automatic process--am I off base?

Hary Gahtoe

Section including actuation and each corner can be re set +/- above preset.
Car recognizes and restarts given inputs

Hary Gahtoe

Found this in the 212 forum. Process is similar in SDS procedure for 230's.
True there's big differences between ABC and Airmatic systems but in terms of SDS adjustments to lower both, the SDS steps are similar for tutorial purposes.


https://mbworld.org/forums/e-class-w...ds-xentry.html