Does the ABC have sensors on the wheels to set body height or is it all accomplished through the ABC control module. I have some weird goings on with my ABC system. I'm pretty sure it's not pump related because even after the ABC warnings and susequent height loss restarting the vehicle eliminates the malfunction warning and immediately restores the ride level. However now the passenger side is 1" lower than the driver's side, hence the question on height sensors/ABC module.

 

Yes, each lower suspension arm has a sensor connected by a lever and link.

 

Sounds like you could be a bad front strut but better to use STAR to test it out.

 

More than likely its dirt in the control valve blocks. There are two identical valve blocks with solenoids for the front and the rear. What happens is that fine dirt particles will prevent the seating of the valve for a given wheel and the height will sag over time until the car is restarted since the pressure is static when the engine is off (fail safe).
What you need to do is rebuild the control block with new O-rings and clean the valve assembly.
This is a high pressure system so follow the instructions that are on one of these forums.
Mbenz will not clean it and will insist on a new block which is about $1700.

 

We changed the rear valve block and that seems to have solved the problem, so far.

 

I need help with my ABC suspension. It has had different problems over the years. I have had the car for about 8 years. I got it with about 46,000 miles on it. When it idled for more than about 5 minutes, it would "squat". I took it in under warranty. They said it had a leak, which they said they fixed. The car was never fixed. I lived with the "squatting" for years. Within the last two years, I have replaced the pump, the front right strut, the left rear strut, the rear valve block, and most recently I had the fluid and filter changed. Once they changed the filter and fluid, the car is actually worse. When I turn the car off, the rear squats down to the tires. When I start the car and move it even a sixteenth of an inch, it comes up. I was driving today on the interstate, and the red light came on and off saying the car is too low, and I need to stop. I pulled off the interstate. To my surprise, it was the front of the car this time rather than the rear! I thought I might have to have it towed. I turned the car off, and the front came up a little, so I did this a couple of times. I still was not up all the way, so I thought of moving the car just an inch, and it came up to normal. I drove it home and put it in the garage. Not sure what to do now. I have had this car in the three different shops, starting with MB. One scan last week said the front left strut had an issue, but I did not believe it as the front was fine at the time, until they changed the fluid and filter. Can a front strut effect the rear?? How do I get a schematic for this system so I can understand how it works better. I know it has four struts, a pump, two valve blocks (??), and numerous sensors throughout the vehicle. How does one know what is bad on this crazy (unreliable) system?

 

Are there two valve blocks total, or two in the front and two in the rear? See my post, please. This suspension is a mess.

 

Sorry to hear about all that grief, I think you've suffered from several maintainability issues. ABC uses hydraulic systems that garages don't understand well enough. The hydraulics are entirely conventional, but the application is novel in the automotive arena. Mercedes didn't fully understand how to make the system maintainable from the outset, and haven't been able to flow down the right approach to supporting it at dealer level.

The system is quite conventional - there's a pump, four struts, some dampers, a reservoir, filter and cooler. There are also two valve blocks. Both front struts are controlled by the forward valve block, which is in front of the left front wheel. There's a rear valve block, in front of the right rear wheel. They're pretty much independent, as long as the pump doesn't fail - but it sounds like it's OK. Other thing you have to watch is the fluid level. The pump absolutely must not be allowed to run dry.

It sounds like your problem is with the valve blocks. The O-rings don't last forever, plus they leak when they're contaminated with dirt. Dealers will replace them at great expense, but all they need is dismantling, cleaning and new O-rings. Its not difficult or expensive, bar the cost of the Pentosin CHF-11S fluid. There are several threads about this - have a look at Howards wonderful W220 maintenance thread here:

https://mbworld.org/forums/5184137-post81.html
https://mbworld.org/forums/s-class-w...03-s600-4.html

Regards,

Nick

 

One can buy Pentosin in the US for a discounted price vs. MB at Advance. Its the quantity that is the problem.

BTW I would replace the filter every year and check the fluid level. Don't overfill. It's better to be at the low marker or just a bit above. The new filters are 3 micron vs. the 10 micron of the original filters.

I've heard that opened/resealed Pentosin fluid goes bad after a period of time so if you top off you should be aware of that. Does anyone know definitely about this degradation interval?

Off topic: BTW since installing Racing Brake 2 piece rotors in the CL55 that save substantial weight over the stock AMG rotors seat of the pants impression is that the ABC system is not working as hard because of the lower unsprung weight. Bumps in the road are softer with increased road feel and cornering prowess. Braking distance has been reduced considerably, I still haven't got used to this. BTW the MB pads are now made by TRW and are a considerable improvement in construction and performance over the Pagid pads stamped Brembo that were installed originally.

 

wow- good to know about the race rotors. any disadvantage to having them over stock rotor?