How to – ABC Suspension flush and filter.

I recently had issues with the front of my c215 dropping after being parked. Assuming a piece of crud in the front valve block, I decided to carry out an ABC Fluid change and filter.

The fluid was black instead of green, and didn’t smell too hot. If the filter does not work, I will be removing the front valve block and replacing o-rings and cleaning it up.

Mercedes WIS states, if the car drops, to filter the ABC fluid. I decided to do a flush as well.

Flush first, then filter with the new fluid, as the flushing process a lot of crud from the system. At no point must the system ingest air, or you will damage the ABC pump

You will need, 6+ liters of Pentosin CHF11S. I bought mine from Germany at about half the price of a uk dealer. You will also need 2 x of the new ABC filters, part no A 003 184 61 01, and a length of 1/2 inch hose with a straight adapter on the end. (don’t get a barbed one like mine, as I had to cut the hose off to remove the OEM pipe!





Step 1: 

Start the car and carry out a rodeo for 15 minutes. This warms the fluid up and allows all the bits to get out of the system.



Assuming you do not have access to STAR, you can drive the car around on some bumpy roads whilst cycling the height adjustment button a lot. This wont be 100% but it will carry out the same function.

Step 2:

Ensure the top of the ABC reservoir is 100% clean as possible

Turn engine off, remove the return hose from the ABC reservoir, and attach it to your length of pipe:

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Direct the pipe into a suitable bucket (at least 10 liters to be safe). WIS says to top up the system through the dipstick hole, but I chose to use the gaping hole that the filter would have sat in:



Step 3:

Have a helper sit in the car and get them to start the car. Using STAR, actuate the Pitching motion of the struts. Be careful here as you must not allow the pump to ingest AIR, and you must ensure that the system has fluid in it all times. Fluid will empty from the reservoir, even when the struts aren’t moving a lot.

If you do not have STAR, you can raise and lower the car repeatedly. This will not get 100% of the fluid out of the struts/pipework, etc as the system doesn’t go to the extremes that the STAR does.

Keep topping up the fluid in the reservoir until you get nice clear fluid coming from the return hose.

Stop the engine.


Step 4:

Insert a new filter into the ABC cap:

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To do this, press in on the spring, which releases a hook on the top half. When its in front you it will become obvious.

Next, ensure your ABC level is correct, and time to carry out a filter.

Step 5:

With the new filter in place, carry out another Rodeo on STAR, then change the filter again. Without access to star, I would drive the car around for a couple of thousand miles, then change it again.

Also, in hindsight, after looking at the new filter, I would drive with the new filter in place for a couple of thousand miles, then change it again, as it cant have taken that much crud out of the system in 15 minutes.

Check the level again and relax!

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2 thoughts on “How to – ABC Suspension flush and filter.

  1. Pingback: How to - ABC Fluid flush and filter - Forums

  2. Thanks Alex, seems straightforward.
    Just had an ABC warning, and think that this will be a regular bit of preventative maintenance which I shall be performing in future to avoid further issues.

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