ABC Hydraulic Suspension leaking?

Tiny
RAMZITH1
  • MEMBER
  • 2001 MERCEDES BENZ S600
  • 5.8L
  • V12
  • 2WD
  • AUTOMATIC
  • 165 MILES
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
Tuesday, October 18th, 2022 AT 9:44 AM

8 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 43,047 POSTS
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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Tuesday, October 18th, 2022 AT 9:58 AM
Tiny
RAMZITH1
  • MEMBER
  • 70 POSTS
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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Tuesday, October 18th, 2022 AT 11:42 AM
Tiny
KEN L
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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?
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Wednesday, October 19th, 2022 AT 12:03 PM
Tiny
RAMZITH1
  • MEMBER
  • 70 POSTS
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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Saturday, October 22nd, 2022 AT 1:19 PM
Tiny
KEN L
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Thanks for the image let me know how it goes. I think you may have fixed it.
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Monday, October 24th, 2022 AT 10:01 AM
Tiny
RAMZITH1
  • MEMBER
  • 70 POSTS
Well, tomorrow Wednesday I have a lot of time free, I will work on it and let you know, thanks.
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Monday, October 24th, 2022 AT 10:17 AM
Tiny
RAMZITH1
  • MEMBER
  • 70 POSTS
Dear Ken,

I have changed and replaced the ABC pressure sensor (pic Attached), and everything is fine now. Thanks
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Monday, October 31st, 2022 AT 10:24 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Nice work, we are here to help, please use 2CarPros anytime.
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Tuesday, November 1st, 2022 AT 11:07 AM

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