I have a 2004 CL500 that I purchased recently. The car is in nearly mint condition, but miles are high, about 172k. Reason I bought this one was it was a good price, but the car fax revealed that owner 1 bought it at Willmington Mercedes, had all service done there, sold to second owner at 144K, and again all service done there. I found out later, the last owner was a salesman at the dealership, and bought the car from his customer as it was impeccably maintained. So, a little bit of history. My problem at hand is the ABC light would come on, then when I shut the car off and restart, it would go away. I checked and the fluid was low, so I added the CHS 11 to the proper level, and I was good for a while. Just over the last week, the light has been coming on (red warning), and it won't go out till the car sits, and upon restarting, it may be good for a while. Then a few days ago, the ABC light messages became very frequent. And over the last 48 hours I have developed a pretty good leak. It seems to be dripping from the underside of the ABC/power steering pump. Also, I have noticed that the fluid seems to flow out the top of the resivior. I have read quite a lot of the posts and stickies regarding the ABC, and my guess is that one or more of the nitrogen canisters have failed, which would account for the fluid drop, and spliiage out the top of resivior. And the canister failure caused the front seal of the pump to fail given the added pressure. Well, that's my guess, but I'm looking for opinions and help. My thought was to buy all new canisters (three I believe), rebuilt pump, remove and clean the hydraulic solenoids, new filter, and flush the system will all new CHS11. So that's my thought, I am open to any help and suggestions. Also, any agree? Or another diagnosis? Also, I want to get the star sds diagnostic software, and I'm not exactly what to get, or where. So any help with that is appreciated also. Thanks for reading, and any help is very welcomed!
Thanks
Ken

 

The first step is to replace the ABC accumulators / nitrogen spheres. Not too difficult or expensive.
You can remove one at a time to see if the rubber diaphragm has collapsed - you shouldn't be able to push a rod into the hole.
You don't lose much fluid, and you don't have to bleed the system afterwards.
Just remember never run the engine with no oil in the reservoir.

You may have noticed that there are two marks on the ABC dipstick. The oil level goes down after a few seconds when the engine starts. This is the pump pressurizing the spheres. If the spheres are all good, the level will shift between the dipstick marks.

Getting into SDS isn't easy. Keep it simple. There are lots of threads; this is probably the best of not a great bunch:

https://mbworld.org/forums/w211-amg/...ts-o-pics.html

Good luck, Nick

 

Thanks Nick, that's a good idea to check and see which accumulator is bad. I guess I can do the same with the pressure relief valve accumulator also?
Thanks

 

Change the accumulators as it is time but don't start replacing unnecessary parts

There's a hose by the abc pump prone to leaking so your pump may be fine as long as you never let the system run dry

 

update
The leak I had continued to get worse and ended up being a split reservoir at the tandem pump. So far have checked three of the four accumulators and none of them seem to be bad, so I think my problem with the fluid loss and system pressure is due to the pump. I ordered a rebuilt pump and waiting for it to come in. I'm hoping that this solves the problem. In addition I'm going to flush and replace all the filters in the power steering and ABC reservoirs .