How to – Change ABC Accumulators on a Mercedes CL (215)

I replaced these on my 90,000 mile CL55 AMG for 2 reasons. 1, my ride quality was suffering over jarring road irregularites (pot holes, cracks in the road etc. 2, at 12 years old, if any where original, they where probably sub-par by now.

You will need:

  • Part number A220 327 01 15  x 2 – Front and rear accumulators
  • Part number A220 320 04 14 x 1 – Return line accumulator
  • 2 x Axle stands
  • 10 mm Spanner
  • 10mm Socket
  • 17mm Spanner
  • Pliers etc for exhaust rubbers.
  • Lint free rags, brake cleaners
  • 1 Litre of Pentosin CHF11S

The ABC Pulsation damper had already been replaced recently and wont be covered in this guide, however, its functionaliy identical to the accumulators, instead of damping oil movments caused by struts, it dampens oil movements caused by the radial piston pump.

Step 1:

Rear first, jack the rear of the car up and put it on axle stands. Remove the 2 rearmost exhaust mounting ( I just removed the bolts) and the middle mounts. This gives enough movement in the exhaust. WIS says to remove the rear section and the heatsheild but theres plenty of room without.

Step 2:

WIS states at this point to bleed the system using the bleed nipples. I have read that these like to shear off and that in reality, if the engine has been off for 30 minutes then the pressure in the system is negligible. The rear ABC Accumulator is located on the Offside rear just behind the rear backbox. If you look up you can just about see it hiding:



It is held in with 2 nuts on one side and 1 nut on the other. (sorry for the rubbish pictures, space is tight)

150118-IMAG0754 150118-IMAG0755


Step 3:

Thoroughly clean the surfaces around the oil feed lines and the hose itself, if there are any bits of rust/grit etc above or around it get them cleaned too. You dont want any bits getting into the system.

Step 4:

Undo the nut holding the oil line on (17mm spanner). I had enough room with a normal long spanner, a short 17mm would have made it easier. You will loose around 100ml of oil when you undo it so keep a rag handy. Try to keep the system open for as little time as possible.

Undo the mounting nuts and pull the exhaust down. This should give you enough space to manouvre the accumulator out.

Step 5:

Insert the new accumulator and bolt it up. Its very much the reverse of the installation.

Now the rear is done.

Now onto the return accumulator.

The new part looks like this: md_64fdc546-a20e-430c-8f32-ffd481ddf633

Step 6:

Onto the return accumulator. This unit is held in with a 10mm nut on one side and a 10mm bolt on the other. It has 2 oil feed connections, one is a rigid connection and one is on a flexible line.

Undo the under panneling that covers the fuel pump/filter and return accumulator:

150118-IMAG0751 150118-IMAG0750You will be presented with this:



I decided to remove the right hand nut and slightly undo the left hand bolt that holds the accumulator to its bracket. I then undid the oil line connections. I placed the flexible connection into a clean emtpy latex glove to prevent dirt getting into it:



Re-installation is again the reverse of removal.

 Step 7:

Let the rear of the car down, loosen nearside front wheel bolts and jack the front of the car up. Put it on axle stands. Ensure the car is secure.



Remove the wheel:



(hmmm shiny brakes).

Step 8:

Remove the wheel arch liner. There are a multitude of plastic 10mm nuts holding this on. Dont forget the 2 8mm undertray bolts at the bottom.

150118-IMAG0758 150118-IMAG0760

Step 9:

You will be presented with:



Its much the same of the rear one, but access is much easier.

Undo the lower mounting bolts and upper mounting bolts:

150118-IMAG0762 150118-IMAG0763Disconnect the lower oil fitting as before, you will loose very little fluid.

Insert the new sphere, bolt it up, put the wheel liner back on, wheel back on and let the car of its stands.

Step 10:

Thoroughly clean the top of the ABC reservoir and dipstick area with a lint free cloth. Start the engine and remove and clean the dipstick. Top up the fluid with Pentosin CHF11S so that its in the middle of the top marking on the dipstick.




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38 thoughts on “How to – Change ABC Accumulators on a Mercedes CL (215)

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      • Thanks for the response. I did the front one today (I have a W220)with ABC but it looks like the actuators are located in the same place. I didn’t completely remove the fender lining. I just unbolted the side towards the front of the car and was able to pull it back enough to get to the accumulator.

        Of the remaining (3), my car has three plus the pulsation damper which is also an air cell.

        From your opinion which of the remaining is the easiest to get to.

        I have one near the driver’s side rear wheel, and another hidden behind the muffler. I think the pulsation damper is located on the passenger side near the front wheel well.

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  6. Great write up and easy to follow instructions.
    I changed mine today and it was in fact an easy job. Thank you so much!

  7. on my 2002 cl55 amg the rear passenger side dips down overnight. Then when I start the car the ABC warning light comes on and it take a few moments to get the right rear back up so I can drive the car… Will replacing the right rear abc accumulator fix this problem? The pump has been replaced about 15k miles ago and did not fix the problem..

  8. Have a 2002 CL500…which dinks and abc light comes on when going over a bump. How much should a shop charge more or less for parts and labor to replace. Im in San Diego area. Thank you for the great info…

  9. Have a 2002 CL500…which dings and abc light comes on when going over a bump. How much should a shop charge more or less for parts and labor to replace. Im in San Diego area. Thank you for the great info…

  10. Thank you so much for taking the time to post this ! You saved me lots of money and your directions and photos were spot on!


  12. I have a 2005 CL65. One of the hoses from the accumulator to the power steering pump has a slow leak. I cannot find the part number for either hose, anyone have an idea?


    • Hi Paul

      No, they are all in difference locations, most notable, the pulsation damper is on the outlet of the pump. The pump should really be removed to avoid debris getting into the system but its possible in situ.

      • Okay thanks for the reply. I was wondering if there was an image/diagram or location on the Net I can find out where the Accumulators are located? Also any advice in where I can buy the parts from? Thanks

    • Good morning.

      There are 4 in the system. One is reffered to as the “pulsation damper” on the outlet of the pump. 2 Supply accumulators (large ones) front and back. And one small return one on the rear. If they are original then you should change them all.

  13. Hi, good morning here is jimmy again my cl55 Mercedes’ the Left side front n rear is lower than the Right side, sometime when drive on the road it happen the front hydraulic strut go down n go back up (not always) should I change all the valve block seal when I replace all the accumulator. Thankyou for your Help.

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