A week ago I bought a 2004 SL500 (105,000 miles) knowing very little about Mercedes Benz. I liked the styling and the hard top convertible aspect. The second day I had it I noticed the right rear of the car sagging after it sat for a few hours. Thus began the saga of learning about the ABC system. After much reading I determined the rear valve block needed new O rings. Ordered rings, ordered pentosin. Bought the (required?) 17 mm crowsfoot tool. Was able to get the mechanism out of the car and on the bench. Changed O rings but found that all of the write ups on the subject left out the fact that it was difficult to get the solenoids out and even more difficult to get them back in. Was afraid I was messing something up with the effort to put the solenoids back in the valve block. At any rate I was ready to put it back in the car only to find that it is physically impossible to get in to re-attach the lines! So I remembered reading about a tool to disconnect the hydraulic lines. Tried to buy the tool from local MB dealer but told it came from Germany. Could not wait. So decided to build my own tool. Took a 9/16 open end wrench, ground it down thinner, filed an angle inside the sides of the wrench. It worked great, probably easier than the correct tool would have. Pulled the mechanism out, installed the pipes and all went back in nicely. After pumping pentosin on the garage floor a couple of times, got the quick connect lines properly hooked up.

Result? Left rear was completely lowered, could not get even get the jack out. Kept pentosin reservoir filled, ran motor several times, tried bleeding (nothing came out). I decided one of the solenoids was no good or the wiring was messed up somewhere. Very discouraged I gave up, ate some lunch, took a nap. Two hours later I decided to start the motor up and try again, and low and behold the ABC worked as it should! After two trial short drives all seems well. I am one happy person! Hope this adds a few details that will lead someone else to success.

 

 

With much fear I went out to the garage this morning to see if car was level. Yea! It was level. Confident enough to give it a longer trial today. Not sure how to do pictures Will give it a try.

 

Good job! My guess is that you had air in the system which need to be purged. You might want to invest in SDS. It can fully actuate the four shocks individually in sequence (called a "rodeo") that can often dislodge particulate that is causing a seal to not fully seat, eliminating the need to rebuild the valve block, and also bleed air from the system

 

I have done a bit of reading about SDS. It seems it might be very expensive for the average do it your-selfer with only one MB. What do you suggest I consider buying that would be useful?

 

You can get a turnkey Chinese SDS clone for around $500, all installed and good to go on a (used) laptop. There is a learning curve, but plenty of us here have it and can help. If not SDS< then your options are to spend around $200-$250 on a hand held tool like the iCarsoft i980 or MBII or the Autel MD802 Elite. Those will read and reset codes from all systems and read live data, but they won't do any coding or actuations. Also, SDS comes with WIS (electronic shop manuals) and other resources that help you learn to DIY.

 

So I am guessing the cheaper handheld ones will not do the "rodeo". Thanks for the previous answer. Just what I needed to know.

 

I am not aware of any 3rd party hand-held scanners that will do coding or actuations (like a rodeo). While those are better than generic OBDII scanners, they don't come close to SDS.

 

Many thanks.

 

Please post a picture of your home-made custom tool.
Very intrigued since i may have to rebuilt my front valve block soon. My car RANDOMLY sags on the driver front corner...some times after only 4-6 hrs of sitting, sometimes after more than 4 days. Go figure.
I got the rings, i read the docs, watched the videos....but have not attempted the actual rebuild.