@Mongo The ABC system is pretty simple. Four shocks, valve blocks, pressure accumulators, tandem (steering/suspension) pump, very expensive Pentosin fluid. If one corner sags, it's most likely that shock. If there's no visible leak, trace back to the valve block/solenoids. If you don't mind a little work (thats easy) "re o-ring" the solenoids. That won't cost too much. The problem is that anytime you address an issue you might have to flush the system. Buy Penstosin CHF11S in bulk, lol. Much cheaper. Also, get the flush/bleed tool https://www.fcpeuro.com/products/merced ... 2203270115
. It'll pay for itself and then some on your first system flush. The system is really easy to work on, seriously. Dealerships totally rob you, $1500 for a flush for twenty minutes of work, $200 of fluid and a $40 filter. The first time I did it, my wife helped by keeping the engine revs higher and minding my scan tool while the car did the "rodeo".
I recently did a flip on a W221 S600 (not my car) for a colleague and who desperately wanted one (after he drove mine) but was terrified of a suspension issue a local car had with a sagging corner after sitting for a day or so. He wanted to replace his W220 with airmatic and had the system worked on before and was totally freaked about the potential cost in the ABC system. I struck a deal with him, that he'd buy the car from me for a set price after I "sorted" it (car had new coil packs and some suspension arms/bushings replaced). The only issue was the valve blocks and accumulators. The fluid reeked and was absolutely filthy. Service records indicated the last time it was done was four years ago. I changed out the O-rings on the solenoids, both accumulators (lots of videos on youtube), flushed the system and all was good. The local dealer that he's used before quoted him a minimum of $4500 to sort it without potential shock replacement costs, with a potential for $11k and they were hinting at that. Total cost was $800 in parts and a several hours of my time. Above all, it was fun and a great learning experience (aside from the fact that I'm a cripple lately and the day after wasn't too much fun).
After it was all said and done (he helped a little), he quipped (He likes nice cars but is clueless about them) that people, him included are stupid about these things and was happy to pay me the delta on my "profit". If I had a shop, I'd do this all day long, it's that easy. The hard part about this car is it's so god damned heavy. My quickjack couldn't get it off the ground (5000#) but I can get my CL63 up (400# less) so I had to use jack stands. No biggie. I could knock it out in 2-1/2 hours if I had more involved experience doing it.
Nothing vast enters the life of mortals without a curse. - Sophocles
Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly.
The worst form of inequality is to try to make unequal things equal.