Greetings,
Just wanted to tell a quick story/ask a question on the issue in progress. I received the 'service brake visit workshop' message on my 04 e55 a week ago at 126k mi. I called my indy and he said it was not a brake wear issue and to take it to the dealer as it should be covered by the 25 year SBC warranty. Dealer takes the car and a few days later calls back to tell me the tech thinks the SBC pump they just put in is defective and they are going to try another one. Fast forward 2 days and now I get a call saying the second pump provided the same result and now the issue is "The internal seals of the master cylinder are leaking causing the lack of pressure. We can’t get the brake system to properly bleed."

Apparently that is not under warranty and they want $1500+ to fix. My indy said that it sounds funny and he thought that should have been covered under the warranty. I can't see in the letter that was mailed anything that speaks to it being covered but wanted any input from the experts on the board. My options are to pay them to fix it, take it to another dealer and see what the response is or send it to my indy who is fantastic (should out to CW Performance in Apex, NC). My question to all those much smarter than I is why would they try to replace the SBC pump if the computer did not identify that as the problem? Wouldn't the computer show the problem being the master cylinder from the beginning and save them the time of swapping the right part? Any advice on what I should do? I called the 800 number on the warranty paper and the corporate office has opened up a CAC? and someone will be calling me back within 24 hours. I'm traveling tomorrow so I said I would come back and get the car today and sort it out later. The advisor is going to test the car to make sure it is safe to drive and let me know.

 

The brake system is brake-by-wire. The seals in the master cylinder have nothing to do with it. Pressing on the brake pedal affects two Hall-effect sensors that transmit their signal to the SBC for the computer to apply the brakes. The tech has to use STAR to bleed the system; it cannot be done manually. Sounds like you need to talk with the service adviser and educate him/her or find a competent dealer.

https://www.scribd.com/doc/14094997/...ke-Control-SBC

Page 28 shows the hydraulic schematic. The master cylinder will hydraulically connect to the two front calipers if the two emergency valves y1 and y2 open in the event of SBC total failure. Otherwise they are closed in normal operation. There is no way to bleed the system using the master cylinder. This requires STAR to activate the pump M1 and then open/close various valves to bleed the system. The master cylinder just acts as a reservoir to hold the hydraulic fluid. Print out the document and take it in to the service adviser with you.

 

Update: I picked the car up from the dealer yesterday. They replaced the SBC pump but the tech wasn't happy with the performance after driving it which led them to think it was the brake master cylinder. I declined to spend the $1500 and drove it back. The service brake light was off and it drove exactly how it did when I brought it there minus the light. I think the tech may have not been happy with the brake performance due to the rotors and pads needing replacement and the brake master cylinder was his next guess. Indy said to drive it hard and see what happens and that the pump may have been the issue all along. Will be doing the pads and rotors in the next week and keeping my fingers crossed.

 

Final update:
Dealer called back and informed me that the part that was the problem was the brake operating unit aka, master cylinder and to bring it back for repair. Scheduling a time to drop it off and get it fixed this week. Hope this story helps clarify the issues that someone else may have down the line.

 

MY CLS 500 is at the dealership getting the sbc system replaced after going back and forth with them to the point I had to call corporate. They finally decided to install the free sbc but charge me 1000$ for the break lines installment saying that whoever previously installed them where wrong causing the issue of the break oil leaks and breaks failing. I agreed to pay the 1000$ just to skip the constant back and forth with hopes that if I contact Mercedes again they will reimburse me for the 1000$.

MY QUESTION IS,, are they charging you for the master cylinder replacement still, And did They run new coils or break lines to your wheels attached to the abc module with the warranty

 

I did not get new brake lines when getting the work done on either of my cars that had this recall. Nor was I charged for any of the work done.

 

I got the replacement for free but no new brake lines