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Mercedes ABC Suspension Fluid Type, DIY Flush

If (Active Body Control) ABC light is ON or is flashing there is a good change your suspension system may be low on hydraulic fluid. When the ABC fluid level gets too low, you may also notice a humming or whining noise coming from the engine. Minor suspension oil leaks can develop on high mileage Mercedes-Benz and may require topping the hydraulic suspension once a year.
In this guide, we cover:
  • Mercedes Hydraulic Suspension ABC Fluid Type
  • How to check the ABC fluid level and
  • How to perform Mercedes ABC fluid flush.

Mercedes uses hydraulic suspension in many models including S-Class, CL-Class, SL-Class, E-Class, etc. Mercedes-Benz cars that have Active Body Control (ABC) suspension use hydraulic fluid. It should NOT be confused with Airmatic suspension which uses compressed air.

Mercedes ABC Fluid Type

The fluid type that is installed at the factory is Mercedes-Benz Hydraulic Oil Q 1 32 0001 manufactured by Pentosin.
If you like saving money, the Pentosin CHF 11S is the same as Mercedes-Benz Hydraulic Oil Q 1 32 0001. In fact it is printed on the Mercedes ABC container as well.

 

Note that this hydraulic fluid is often used in power steering system as well.

How to check Mercedes Hydraulic ABC Fluid Level

Get at least two quarts of Pentosin CHF 11S.

No special tools are required to check Mercedes ABC fluid level. All you will need is a clean rag and make sure to use gloves.

  1. Turn off the engine and locate the ABC reservoir in the engine bay.
  2. Remove the dipstick.
    • The dipstick has two sides. One is for checking the hydraulic level fluid with engine off, one with the engine on.
      • Engine On   – MOTOR AN UNBELADEN
      • Engine Off  – MOTOR AUS UNBELADEN
  3. Wipe off the dipstick.
    • Note the side that says “MOTOR AUS UNBELADEN”. Since we are checking the level with the engine off we will use this side.
  4. Fully reinsert the dipstick into the reservoir and pull it out.
  5. Read the level on the dipstick.

How to flush Mercedes hydraulic system?

In this section, you will find instructions on how to flush Mercedes-Benz ABC suspension yourself. Doing the work yourself can save you hundreds in comparing to having the dealer or a mechanic do the flush. At the dealer flushing, ABC system would run between $580-$800.

What you will need

AGA Mercedes Benz ABC Flush Tool AGA Mercedes ABC Tool  – OPTIONAL (eBay Link)

AGA tool is not a required but can make the job easier on W221, W216. Flush can be done without the tool. This tools also does not work on W220.

10 quarts of ABC Fluid: Pentosin CHF 11S
 Gloves, Glasses, Screwdrivers, Clean bucket

Important

  • Wear gloves and glasses when changing Mercedes ABC fluid.
  • Do not allow fluid to fall on your vehicle paint.
  • It is important to work on a clean environment. No particles or dirt should be introduced to the ABC system.
  • The recommended method is to use Star Diagnostic and activate the ABC system to warm it up. Go to ABC Body Control > Actuation > Activate Rodeo mode to bring the temperature of the ABC system to 80 degrees Celsius. If you don’t drive Star Diagnostic drive the vehicle for 30 minutes to warm up the ABC system.

Instructions

  1. Drive vehicle for at least 30 min or more. During the driving press the ABC button several times to engage the ABC pump. This will warm up ABC fluid which is recommended.
  2. Turn off the engine.
  3. Remove bracket on top of the ABC reservoir. ABC reservoir is located in the engine bay, behind the driver’s side headlight.  You will need to remove the large bolt, then slide bracket. This will give you enough room to remove the cap.
  4. Remove the large cap on top of the ABC reservoir. The cap has the filter integrated below the lid. Keep a pan next to the ABC reservoir to collect ABC fluid that will drip from the filter.
  5. Once the cap and filter are removed, the next step is to insert the AGA tool into the ABC reservoir and press it in. If you are not using the AGA tool, you will need to disconnect the return line that goes into the ABC reservoir and route with an extention to a clean bucket that can hold at least 10 litters (or quarts).
  6. Connect a clear hose to a container that can hold at least 10 quart (or litters).
  7. If you are using start go to ABC COntrol Unit > Acuations > Cyclically alternating actuation of the front and rear suspension struts (pitch) >F3 If Star Diagnostic is not available, use the ABC switch in the dashboard and cycle it on and off every 5 seconds.
  8. Open all your ABC fluid container and get them ready. The fluid level on ABC reservoir goes down quickly. You should not let the reservor get empty.
  9. Start the engine.
  10. Have a friend cycle the ABC on and off every 10 seconds.
  11. As the ABC fluid level goes down, add ABC fluid. Do not let the system go to MIN.
  12. Once you have added 10 quarts of fluid, stop the engine.
  13. Replace the filter and install it.
  14. Check the ABC level. Add or remove fluid as needed.

Replace ABC Filter

You will need a new Mercedes-Benz Hydraulic Self-Levelling Oil Filter W/ ABC Genuine Original 0031846101.

  1. The ABC filter is mounted on the ABC reservoir cap.
  2. To change ABC filter remove the ABC cap.
  3. Twist the filter and housing counterclockwise to unlock it from the cap.
  4. Remove the filter from the housing.
  5. Insert the filter into the housing.

Additional Resources

Here is a video that demonstrates how to do a complete ABC system flush.

Frequently Asked Questions

Which Mercedes have ABC suspension?

  • Chassis that can be equipped with ABC suspension include 215, 216, 220, 221. The models with ABC suspension will have CODE 487 Active Body Control.

What is Mercedes ABC Recommended flush interval?

  • We would recommend flushing Mercedes ABC system approximately every 50,000 miles.

Use a vacuum pump to suck out the old fluid?

  • Yes, but using a vacuum pump will not change all of the ABC fluid. You will be replacing only about 30% of the fluid by sucking out the old fluid and filling with new ABC fluid. Make sure to do this with the engine off.
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