ABC Hydraulic Suspension leaking?

2001 MERCEDES BENZ S600
165 MILES • 5.8L • V12 • 2WD • AUTOMATIC
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RAMZITH1
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Hello,

I noticed some hydraulic oil leak under the car front left side and the car drop down only left side, checked there are no leaks from the front valve block unit or the shock absorber. i found oil coming from the top of the ABC fluid tank, see picture.
I opened the ABC valve block unit to change the seals and found all okay, but changed with new ones and fixed back, there is no leak.
Again, the car drops down from the front left side and the same oil leaks from the top side of the tank.
I appreciate your kind help me, i use to get professional help from you to solve my problems with this car.


Thanks,
Ramzi
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Oct 18, 2022 at 9:44 AM
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STRAILER
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This problem happens when the valve inside the hydraulic control unit leaks and bleeds the system down and back into the reservoir. These systems are notorious for problems. Check out the images (below). Please let us know what happens.
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Oct 18, 2022 at 9:58 AM
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RAMZITH1
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Please note that I don't have the same picture you sent to me, my car is ABC Hydraulic system and not AIR Matic system, please see the attached picture. thanks
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Oct 18, 2022 at 11:42 AM
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STRAILER
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Got it, we have no information on the ABC suspension but I have had some experience with it. The leak and the fact the suspension drops down means the control valve is allowing the system to bleed down and over fill the reservoir which causes the leak. You said you checked the unit but how was this done?
Oct 19, 2022 at 12:03 PM
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RAMZITH1
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Dear Ken,

Done according to the instruction on the web (http://mercedes-abc-drive-carefully.blogspot.com/2014/08/overview-abc-system-isthe-key-part-of.html), it's not allowed to attach the PDF file, sorry, you can download it from there. I think it is useful for any future references.
Now I have checked the right side and see under the car which is ABC pressure sensor (pic Attached) found leaking, will replace with another one and let you know what happen soon.
Thanks
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Oct 22, 2022 at 1:19 PM
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STRAILER
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Thanks for the image let me know how it goes. I think you may have fixed it.
Oct 24, 2022 at 10:01 AM
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RAMZITH1
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Well, tomorrow Wednesday i have a lot of time free, I will work on it and let you know, thanks.
Oct 24, 2022 at 10:17 AM
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RAMZITH1
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Dear Ken,

I have changed and replaced the ABC pressure sensor (pic Attached), and everything is fine now. Thanks
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Oct 31, 2022 at 10:24 AM
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STRAILER
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Nice work, we are here to help, please use 2CarPros anytime.
Nov 1, 2022 at 11:07 AM