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!

How to – Change Rocker Cover gaskets and reseal breather covers on the M113/M112 engine

A common failure point on these engines is a persistent oil leak on the top of the engine. It leaks from the rocker cover, then onto the exhaust manifolds and can make quite a mess.

It also leaks, in a lot of cases, more heavily, from the breather covers, which dont have gaskets and are sealed onto the rocker covers. These make a real mess and leak onto the coil packs, THEN onto the exhaust manifolds.

This problem affects all M113 engines so any 500 engined cars from 1996 up to 2006 ish. including 55 amg, kompressor or non kompressor. The steps to change are basically the same across the board. The procedure is nearly identical for M112 engines, but part numbers and breather hoses etc will be slightly different.

You will need :

2  Rocker cover gaskets, part numbers:

A113 0160 221
A113 0160 321

You wlil also need to replace 5 of the aluminium screws with updated steel ones as the old will snap if you try and re-use them.

These are part number N000912005010 and you will need 5. You will also need Loctite SI5980 Silicone Gasket Maker.

Step 1

Remove engine covers and air boxes/hoses:


150213-IMAG0863Note there is a hose on the right hand air pipe that goes to the right hand rocker cover that will need removing. Pay special care to removing this as you do not want to damage it.

Step 2

Remove the coil packs  from both banks.

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Note the copious amounts of oil covering my rocker covers.

Step 3

Take note of the following locations. You will need to remove these brackets etc as they are held in place with the E10 bolts that hold on the rocker covers.


Front Left Vaccum valve has 2 E10 bolts holding it on , and also holds on a ground connection underneath it (its hidden by the rubber pipe).


The front dipstick tube mount shares the E10 bolt and needs to be moved out of the way when lifting the cover off.

There is a 10m bolt holding on the gearbox dipstick tube onto the rocker cover which needs to be removed.


This fuel pipe on the right hand side on the back had to be removed on mine. A fair amount of fuel did leak off so get a towel or rag handy.

Step 4

Remove all the E10 bolts. There are longer ones on the top and shorter ones on the bottom, so no need to remember which ones go where.

Remove the breather hoses fron the covers on boths sides. On mine they where not brittle but where a bit spongy, I used a 14mm spanner to help them come off. I did not need to replace them, but do keep it in mind, should you need it.

They should then come off pretty easily. Do not try and pry with a screwdriver as they are brittle and will break easily.

You will be presented with this:

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Ensure the engine is covered and bring the covers somewhere so you can work on them:



Step 5

This is the boring boring BORING tedious bit. The resealing of the breather covers.

The channels have to be meticulously clean otherwise the new sealant wont cure properly and they will still leak.  You must also ensure that all the screw whole and breather posts are completely clear so that they seal properly for the same reason and to ensure that you get no old selant falling into your engine and clogging oil ways.

150213-IMAG08742 oiley rocker cover gaskets. Remove the screws holding the breather covers on and prise them off carefully.

150213-IMAG0875You must clear out all of the grooves of the sealant surfaces on both covers. You must also ensure all the groves and the screw posts and breather posts have been cleared off too.  This is a slow process as they do have to be completely clear of all old gasket material. I used a combination of brake cleaner, degreaser, and a small screwdriver.  This is half of what I cleared out:


Afterwards, When the other half wasnt looking, I chucked the lot in the dishwasher :)

150213-IMAG0878Hot wash with a bit of degreaser, nylon brush afterwards with and then came out pretty well:

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Step 6

This is the resealing bit. I only took pictures of the smaller one as I didnt want the larger ones to cure before placing them together. WIS states to only use a 2mm bead, so less is more here. You also dont want bits of sealant coming off and ending up in the system.

Make sure you dont forget to seal the screw holes and the breather posts. Run the bead and then place the cover on in one motion. Use the new screws to secure the covers and tighten to 4nm.


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Step 7

Take the rocker covers back to the car with the new gaskets and fit them :) Place the gaskets into the rocker covers, then place the covers back onto the heads, ensure you havent trapped any wires, and that any brackets etc mentioned before are in the correct place. Re-connect the breather pipes back onto the freashly re-sealed breather covers. A bit of silicone spray helps them back on. If yours break or split replace them as they will cause an air leak and running problems.

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Put the coil packs back on and give the the gasket/sealant a couple of hours to cure. Start the engine and check for leaks. If you have none, happy days, you are all done.








How to – Repair faulty/failing ABC Strut top rubber mounts

On 215’s and 220’s the top of the abc strut comes loose from the top of the rubber mounting, as can be seen in this picture:

This is with the car jacked up so the wheel is off the ground. You can see that the strut has seperated from the top mount and is hanging down, from the top of the strut mount.

From the engine bay, you should be able to see this gap at the top of the strut:


If this gap closes up when the car is jacked up them the rubber top mount has failed. It creates this kind of play in the system:

As you can imagine, this gives about 15 mm play in the shock mounting which isnt great for bigger potholes or undulations in the road that allow the strut to drop and then move back up again with the wheel as opposed to actually doing some damping.

The ideal solution here would be to re-bond the top of the strut with the bottom of the top mount, but I dont think there will be anything reliable here, so instead we are going to add a bush to the top of the strut mount, underneath where the strut travel sensor connector is.

To do this you will need:

  • 10mm rubber sheet (mine was 10cm squared and was plenty.)
  • 35mm Pin spanner (an adjustable one is not strong enough, it must be fixed)
  • A whole saw.

I got all the bits I needed on ebay for less than £25.

Firstly, remove the connector for the strut travel sensor. You must be carefull with this as if you damage it, you will need a new strut! Squeze the outside connectors with some pliers, and pry up gently, it will click and lift straight out:



Once you have this off, use the pin spanner in the wholes on the top mount, they are quite shallow, so if you have an ill fitting pin spanner, you may need to drill them through to get better grip. Luckily on mine I was able to remove them without drilling the holes.

This must be done with the car on the ground, as you want the weight of the car pressing on the struts. You also must ensure that only the top mount bush rotates and not the strut itself! If the strut rotates you will damage the hydralic line and fitting.

Once off, you will have this:

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Grab a 35 mm hole saw (I think this is what I used, but do measure) and cut a disc shaped piece out of the sheet of rubber:



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I used a cardboard box as the base for cutting, which allowed the rubber sheet to curve slightly, giving my disc these odd diagonal edges, but this isnt a problem.

Drill out the center of your disc using a 20mm hole saw, it has to be bigger than the whole in the original bush, as there is a small lip on the strut itself, It must sit below this:

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Now go back to the car and insert the bush over the top of the strut and then screw the original top bush/stop back on, you want to sandwitch the bush between the car mount and the top bush/stop. You must ensure you get the top strut back on enough so that the level sensor can clip back on. Mine ended up a tad squished, In the future I would use a bit of silicon spray on them whilst fitting to prevent this.

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