Mercedes ABC Suspension
Vehicle arrived with rear end sitting low and ABC warning message on dash. Had low pressure and rear suspension height low faults stored - found system pressure at 12 bar fluid very dirty/black. Tech Installed new Tandem pump now pressure is correct 190-200 bar, But vehicle sitting very low at all 4 corners now :( tried bleeding the system got a bit of fluid but no nothing as the block off valves are probably closed. we can not get Pitch or Rodeo mode to work either - currently no faults are stored but the vehicle will not raise up its sitting very low. If i hold the vehicle at normal ride height on hoist and start it up there is no dash indicator i can select the raise up function and dash says ABC raising as normal but nothing happens? also i can actuate all 4 block off valves with scan tool and see the miliamps readings change equally and as commanded. What am i missing why wont this the car stand up?
Got an SL500 in the shop with a leaking tandem pump. The pump is made by LUK. It is leaking in the middle where the radial piston pump section mated up to the scroll section. I've been burned by this before on 2 BMW with ARS which utilize the same pump. The problem turned out to be a collapsed and plugged High Pressure line feeding the valve block. I know you said the pressure is now ok, so this
Try to compress the tank with a little shop air this can help it flow. Also do you have any faults now? Try compressing and revving the engine. They some times take time to come back alive after replacing the pump.
I just worked on an s55 with abc. Did the pressure line, rear valve block, fluid and reservoir filter. When I went to bleed it out all I did was press the dash button from no lights to 2 light back and forth 15 times while adding fluid. I did read after doing this to put the vehicle in the air and listen at the valve blocks for whooshing like air is still in the system, and to repeat. I’m not an
Yes i agree with the shop air into the reservoir but not to over do it.. I use a plastic/ rubber tip add a little air and watch the reservoir slightly expand.. Not to much.. Also you don't want to ever have the vehicle / suspension completely colapsed when doing this ( air suspension included) as this can damage struts.. Abc suspension is very sensitive to contamination and as with any fluid it
The ones I’ve had issues pumping up after repairs have been due to excessive air. I usually start cracking the lines loose in succession from the pump to the valves to the springs while the engine is running. When I get fluid I tighten the line and move down the line. Usually by the time the air is evacuated at the valves the vehicle starts to raise. At that point I let it raise then turn it off
Some have said to put air pressure in the reservoir. This procedure is valid and has been done. I find this is needed to be done sometimes to prime the pump after replacement. But once you have pressure your obviously pumping... At this point we are not allowing the return fluid to re-enter the system either as I wanted to do the pitch mode to properly flush out the system/struts. I suspect I
Do you have a full system scan report? What scan tool is being used? Typically, only SDS can really be trusted to work on this suspension. Also is the pump new or rebuilt/used? Be weary of the rebuilt units. I have had such bad luck with those, I only use new OEM, or pass on the job. Early 230’s used a feed valve at the entry of the ABC pump. New pumps will include this, but rebuilt/used ones
Using Autologic tool, no faults are stored in ABC System. - at this point we suspect the valve blocks may be restricted still not getting any flow to the struts/ vehicle will not raise up at all sitting very low! Pressure correct with No leaks. Going to remove and disassemble the valve blocks for visual inspection on Monday
We all love AL; I have the tool myself. However, Mercedes has never played well with the aftermarket. One of the reasons I caved and acquired the SDS was due to all the erroneous codes, data, and interpolation issues I experienced with the gamut of aftermarket scan tool offerings. If you do not have access to an SDS to back up your findings, I would just stay privy to the possibility the info
Removed the front and rear valve blocks and disassembled - dirty fluid in there but no chunks or large debris blocking inlet filters.. Bench tested the 4 blocking valves and 4 actuation valves. All have similar 2.6-2.7 amp draw. Noticed none of the actuation valve soleonids click or move when powered up? Blocking valves move. Carefully grabbed the pintle of one of the them and gave a bit of
Well done! One for the memory banks.