Car: 2003 Mercedes SL500
Symptoms: car’s front drops 3-4” within 1 hour after engine is off, after engine start car height goes to normal. Red ABC 'low height' warning message is displayed every time I start the car but goes away in 30 sec or so.
Since there where no external leaks on shocks/lines it must be internal leak in ABC valve block. Nice description of ABC suspension is here ABC Suspension
So after reading many posts I thought I should try cleaning valves before replacing them (cheapest unit I can find was $1200 from ESC tuning
2003 Mercedes Benz SL500 Base V8 5.0L > Suspension > OEM > ES#1780752 Control Valve For Active Body Control - 2203201258
here is place where they rebuild them
00-06 Mercedes Benz Suspension Valve Block A2203200358
It took 3 hours of pretty dirty and unpleasant work but results are impressive – car stopped dropping and ride became much more stiff and sporty.
Because I cannot find anywhere in internet info on how exactly to clean ABC valve blocks I thought I would write brief DIY sequence here:
1. Block access: raise front axe and remove front left wheel and wheel liner
A lot of pictures can be found here
http://www.benzworld.org/forums/w215-cl-class/1455132-w215-abc-pump-valve-block-hpe.html
2. Bleed residual pressure with both front wheels off the ground using small bleeding screws on the front shock lines
3. Now you are ready to remove valve block and take it home for cleaning. There are many ways how you can do it but here is what I did:
4. Now with Valve Block off the car you can take pressure damper and holding brackets off (big black bulb and black metal plates, all 10 mm)
5. Carefully clean block outside with ethanol and remove Plastic Clip which holds valves together, plastic clip between regulating valves is shown on Pic.2 (From here I will write for Check Valves only, Regulating Valves are similar). Plastic clips are fragile! Use two pair of pliers to press them on both sides and slide them out
6. Use adjustable pliers to carefully turn valve (garb at the VALVE BASE) to 45 degree angle: after some wiggling it should come out.
7. There is a spring for each check valve – do not miss them! Picture of all valves taken apart is here
http://www.benzworld.org/forums/w220-s-class/1586359-abc-valve-a2203201258-a2203200358.html
8. Clean valve with soft tissue/ethanol, Pic.3, remove plunger and clean its internal o-ring (mine blue 0-ring was very dirty). Check valve seat for scratches. There are 3 areas which can cause leak: dirty valve seat, leaking o-ring or weak returning spring. To be safe I stretched spring for a bit ..
9. For regulating valves plunger is not removable so I just pushed it back and forth with pliers while spraying with ethanol.
10. Put everything back together (except front wheel liner), check fluid level in ABC tank, add Pentosin 11s if necessary. Start engine with wheels on the ground and stop after 1-2min for 5-10 min, add more Pentosin. Now you are ready to bleed the system – slowly cycle through height modes 15 times, it should be enough. Go check for leaks around valve block. If there are no leaks put liner back.
11. Open your beer and celebrate – you just fixed your Mercedes and saved yourself $2000!
PS To be hones you don’t have to remove valve block to clean valves, but it is just much easier to do so for the first time
Symptoms: car’s front drops 3-4” within 1 hour after engine is off, after engine start car height goes to normal. Red ABC 'low height' warning message is displayed every time I start the car but goes away in 30 sec or so.
Since there where no external leaks on shocks/lines it must be internal leak in ABC valve block. Nice description of ABC suspension is here ABC Suspension
So after reading many posts I thought I should try cleaning valves before replacing them (cheapest unit I can find was $1200 from ESC tuning
2003 Mercedes Benz SL500 Base V8 5.0L > Suspension > OEM > ES#1780752 Control Valve For Active Body Control - 2203201258
here is place where they rebuild them
00-06 Mercedes Benz Suspension Valve Block A2203200358
It took 3 hours of pretty dirty and unpleasant work but results are impressive – car stopped dropping and ride became much more stiff and sporty.
Because I cannot find anywhere in internet info on how exactly to clean ABC valve blocks I thought I would write brief DIY sequence here:
1. Block access: raise front axe and remove front left wheel and wheel liner
A lot of pictures can be found here
http://www.benzworld.org/forums/w215-cl-class/1455132-w215-abc-pump-valve-block-hpe.html
2. Bleed residual pressure with both front wheels off the ground using small bleeding screws on the front shock lines
3. Now you are ready to remove valve block and take it home for cleaning. There are many ways how you can do it but here is what I did:
a. Disconnect Line 1 and Line 2 from aluminum Block 1 Pic 1. To avoid contamination in hydraulic system I put saran wrap/electrical tape at the end of each line. Oh and use gloves!
b. Remove 10 mm Bolt 1 which holds Block 1 on bracket and electrical connector to the sensor, slide Block 1 to the side
c. Remove Lines 3-5
d. There are 3 10 mm nuts which hold Valve block – now you can access them and remove Valve Block
e. Carefully mark and remove 4 electric connectors - they are fragile!
f. Put plastic tray under car - lines are not leaking badly but I got 0.5 l of oil over 2 hours..
b. Remove 10 mm Bolt 1 which holds Block 1 on bracket and electrical connector to the sensor, slide Block 1 to the side
c. Remove Lines 3-5
d. There are 3 10 mm nuts which hold Valve block – now you can access them and remove Valve Block
e. Carefully mark and remove 4 electric connectors - they are fragile!
f. Put plastic tray under car - lines are not leaking badly but I got 0.5 l of oil over 2 hours..
4. Now with Valve Block off the car you can take pressure damper and holding brackets off (big black bulb and black metal plates, all 10 mm)
5. Carefully clean block outside with ethanol and remove Plastic Clip which holds valves together, plastic clip between regulating valves is shown on Pic.2 (From here I will write for Check Valves only, Regulating Valves are similar). Plastic clips are fragile! Use two pair of pliers to press them on both sides and slide them out
6. Use adjustable pliers to carefully turn valve (garb at the VALVE BASE) to 45 degree angle: after some wiggling it should come out.
7. There is a spring for each check valve – do not miss them! Picture of all valves taken apart is here
http://www.benzworld.org/forums/w220-s-class/1586359-abc-valve-a2203201258-a2203200358.html
8. Clean valve with soft tissue/ethanol, Pic.3, remove plunger and clean its internal o-ring (mine blue 0-ring was very dirty). Check valve seat for scratches. There are 3 areas which can cause leak: dirty valve seat, leaking o-ring or weak returning spring. To be safe I stretched spring for a bit ..
9. For regulating valves plunger is not removable so I just pushed it back and forth with pliers while spraying with ethanol.
10. Put everything back together (except front wheel liner), check fluid level in ABC tank, add Pentosin 11s if necessary. Start engine with wheels on the ground and stop after 1-2min for 5-10 min, add more Pentosin. Now you are ready to bleed the system – slowly cycle through height modes 15 times, it should be enough. Go check for leaks around valve block. If there are no leaks put liner back.
11. Open your beer and celebrate – you just fixed your Mercedes and saved yourself $2000!
PS To be hones you don’t have to remove valve block to clean valves, but it is just much easier to do so for the first time
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