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ABC - How to bleed and also make your own service tool

Discussion in 'DIY: Suspension, Steering & Brakes' started by Will Barber, Oct 29, 2018.

  1. Will Barber

    Will Barber Senior Member

    Messages:
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    Joined:
    Jan 25, 2010
    Location:
    Cheshire
    Your Mercedes:
    2012 CL500 (4.7L M278)
    After realizing that the pulsation damper had never been changed despite the 60k FMBSH, as stated in a previous post the dreaded ABC 'groaning' noise appeared a couple of weeks back.

    The following is not set in stone and is only my opinion on how it can be done without the need to spend lots of money at either main dealerships or indeed some independent MB outlets. Besides, I thought I would try and give something back to this fantastic forum and its members. I only hope this is of some use to you all.

    Service Tool

    Knowing that the reservoir design has changed since I last did an ABC flush on my old W215 CL500 where the ABC fluid returns to the ABC reservoir at the top, I thought I'd come up with a service tool that will allow you to flush the system where the ABC fluid returns centrally in the bottom of the reservoir. This later "pain in the arse” type is fitted to E class and S class vehicles amongst many others.

    A service tool is available from Germany at around £140 + shipping, but I made mine for around £2! If you have access to a lathe, all you need to do is spin an aluminium bush up as shown in the accompanying diagram. To that, all you’ll need is a small length of 15mm copper plumbing pipe and a piece of garden hose.

    Firstly I made the bush to replicate the bottom of the ABC filter cartridge holder that pushes into the bottom of the reservoir. So a bush 40mm long was turned to a diameter of 37.8mm as per the cartridge hole (check yours is the same, it may be slightly different in size), and a 13mm hole bored all the way through. I then increased the internal bore to just under 15mm, 30mm deep (so the 15mm copper pipe can’t be knocked all the way through). A groove is then added as shown and an O-ring added, making sure that the fitted O-ring size does not exceed 38.3mm (again measure the original to replicate). Once I was happy with the bush, I parted it off and thoroughly cleaned it, before adding a bit of Loctite and pressing the copper pipe into the bust all the way until the ‘stop’ as shown. A 1½ metre length of garden hose was then dipped in boiling water and pushed over the end of the pipe and became a shrunk fit. Perfect and now ready for the flush.

    drain tool.jpg

    The following procedure is based on a 2012 CL 4.7L Twin Turbo with the M278 engine, and should be okay for almost every other ABC equipped model from 2007 on.

    Parts Required

    Be warned, despite what videos you watch on Youtube, you WILL need 2 new seals (part No. A2103270060N) that sit above and below the filter. The original seals swell in size by around 20% and you will NOT be able to get them seated back into the recesses of the filter cartridge so make sure you have new seals before you even think about releasing the filter from the cartridge holder! You will also need a new ABC filter (part No. A0031846101) and 6 to 8 litres of Pentosin CHF 11S hydraulic fluid.

    Workshop Requirements

    If you have access to a 2-post ramp (like I did) it makes the job much easier. However it is still easily done with a car jack and 4 axle stands. So, either position the car on the ramp or support on 4 axle stands… making sure that all 4 suspension struts are fully extended and there is no load on any of the wheels.

    Pulsation Damper

    Firstly, with the M278 engined CL and S-Class vehicles, the pulsation damper is very conveniently located at the top front of the engine, smack bang in the middle. Access is superb and all you need to do is unclip and remove the main central engine cover and that’s it. Place some absorbing cloth beneath the pulsation damper, and with a 17mm open-ended spanner and extension (ring spanner on the end works fine), remove and discard the old pulsation damper. New pulsation dampers seal by a tapered seat so there’s no loose seal etc. to worry about. Screw in the new pulsation damper into the pump body and nip tight (I don’t have the torque figure to hand so do check).

    To Bleed

    Next on the LH side of the engine bay, remove the fixing retaining the washer bottle and ABC reservoir bracket, push the reservoir out of the grommet, unscrew and remove the ABC filter cartridge assembly.

    Detach the bottom section of the cartridge from the top (30 degrees anti-clockwise) and remove the old ABC fluid filter. DISCARD the 2 O-rings. Clean the cartridge sections, fit the NEW O-rings above and below the new ABC filter and reassemble the cartridge sections. Leave to one side as you will now bleed the system.

    Guide your new self-made service tool into the bottom of the ABC reservoir and push down to confirm the O-ring on the toll seals the return. Guide the end of the garden hose into a suitable clean bucket (enough to hold at least 1 litres). Prepare your many litres of Pentosin by removing the tops and lining them up close to hand. Start the engine and allow to idle…. The level of the fluid in the reservoir will now start to drop as the old dirty fluid is expelled into the bucket. Keep the reservoir half to three quarters full of new fluid until clean green fluid is expelled into the bucket, which usually takes around 4 to 5 litres. Once clean fluid is expelled, turn OFF the engine.

    Next lower/position the vehicle back on level ground, but do NOT yet fit the new filter assembly. Now start the engine again, and with the aid of an assistant, repeatedly raise and lower the car via the raise and lower switch in the car, again topping up the reservoir whilst doing so. I usually raise and lower the car around 10 times, until I either run out of Pentosin or I feel it’s had enough fluid pushed through the system. Turn the engine OFF and remove the bleed service tool you made earlier. Fit the ABC filter cartridge assembly into the reservoir, start the engine, allow to idle for 30 seconds then switch OFF the engine. Allow the ABC fluid level to settle for a few minutes. Adjust the ABC fluid level in the reservoir by adding fluid or removing with a clean syringe and hose.

    Refit the reservoir back into the carrier bracket and secure the washer bottle to the bracket with the previously removed fixing.

    Job done !!
     
  2. OP
    Will Barber

    Will Barber Senior Member

    Messages:
    195
    Likes Received:
    17
    Joined:
    Jan 25, 2010
    Location:
    Cheshire
    Your Mercedes:
    2012 CL500 (4.7L M278)
    I haven't a clue where to edit the post, so here is a more accurate drawing of the bleed tool you'll need to make.
    Bleed tool MB.jpg
     
  3. Blobcat

    Blobcat Moderator

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    Your Mercedes:
    W213 E220d, Smart R451 CDI, Porsche 911 C2S, Land Rover 110 County SW
    If you wish to discuss this thread please post replies here
     

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