I have a 2014 e550. I recently picked up rear AMG calipers with rotors. I wanted my calipers painted so I removed all four. *I should have clamped the brake lines but I didn't. I said, I'll just let it drain out since I am going to be bleeding all 4's anyways. *whole system ran dry. finally 3 weeks later calipers are ready for install. installed them and here are the events that happened exactly.

1. poured oem brake fluid into the reservoir until the level became steady topped off
2.connected the power bleeder to the reservoir- schwaben
3. pressurized the system to 18psi- although later on I found on xentry WIS or w.e that ur supposed to do 2.0 bar/30 psi
4. bled starting from farthest>closest to the MC.....I ran so much fluid through that there were absolutely no air bubbles
5. made sure all the bleeders were tight
6. I get in the car and pumped the brakes a couple times....I don't recall if I did it slowly and soft or hard and fast...NOTE: the MC was dry for weeks...I should have slowly pumped the pedal right after pouring fluid in before doing the pressure bleeder.

anyways I spent about 3 days trying to figure out why the pedal doesn't get hard and and wont hold pressure. I thought there was still air in the system...maybe in the ABS? MC?
I bled it prolly 100000 times...no air bubbles was coming out of the bleeders...I had a clear hose connected to each bleeder with its own bottle. activated the esp on xentry-which actuates It for 5 seconds..did It a couple times....no change...I don't even think it was doing/bleeding anything...

bled the MC by disconnecting both lines and hooking up them plastic fittings with tubes going back into the reservoir...slowly pressed and depressed the pedal prolly 200+ times lol....I didn't wanna remove the MC as I thought it would be the same thing as the real way of bench bleeding by putting it on a vise and pushing it with a screw driver

proceeded to bleeding the brakes again after this....SAME THING

PEDAL KEEPS SINKING TO THE GROUND
IT DOES HAVE SOME PRESSURE TO IT THOUGH WHEN PUSHING

IT ONLY BUILDS PRESSURE WHEN I PUMP IT HARD AND SUPERFAST BUT AFTER ABOUT 5-10 SECONDS THE PEDAL GETS SOFT AGAIN AND ALL THE DOWN TO THE FLOOR
I DIDNT THINK IT WOULD BE THE MC.....CAR HAS 20K MILES AND VERY WELL MAINTENED...I KEPT INISTING THAT IT WAS MAYBE AIR STILL IN THE SYSTEM LOL

after days of troubleshooting and countless bleeding 2 man pump and release/ power bleeding...no luck
no leaks on any of the calipers

now I ruled out its gotta be the MC...I must have blown the seals somehow in the beginning since I let it run dry

oh and i noticed...i had my buddy step on the brakes while i was watching the pistons and the rears were barely compressing... the front u can see the caliper and rotor move a bit...the rears yes piston was moving but not as hard...its like theres only little pressure..the only time the rears would clamp hard is when i pump the brakes vigorously and fast then it build up pressure and i hold it. i let go and after a couple seconds it soft again

LASTLY JUST EARLIER TODAY....LAST NIGHT WHEN I PARKED THE CAR....FLUID LEVEL WAS ON MAX....CLOSED THE RESERVOIR CAP...MORNING I GO AND OPEN THE CAP AND IT WAS SO FULL IT WAS ALMOST LEAKING OUT OF THE RES...PUMPED THE BRAKES A COUPE TIMES AND THE FLUID WENT BACK TO MAX LEVEL....10-15 SECONDS LATER...FLUID STARTED TO COME BACK UP AND LEAKED OUT SO I PUMPED IT TO GET IT BACK TO MAX LEVEL AND THEN I JUST CAPPED IT.....WEIRD SHHHH HUH?! WTF

story of my life....never thought i would have so much problems on just bleeding the brakes...sorry if i repeated myself but im just trying to explain what is going on exactly cuz this has been PITA and consumed 3 days of my time lol...if would have just clamped the lines...it would have been cake...

please let me know what you guys think?
i will be ordering a new MC and i hope it is the problem...i have tried just about everything..if this doesn't fix it then idk...lol

BRAKE EXPERTS

whats the correct way on using the power bleeder...i read somewhere that you should still have someone pushing the pedal while its pressurized when bleeding....if that's true what is the sequence? while it pressurizes- pump and hold then bleed????

and of course when i get the new MC i will bench bleed it

as far as ABS bleeding...i have XENTRY but all that's on the actuations for ESP is high pressure and return flow pump/ left rear pressure regulating valve pressure/ SBC hold
theres isn't a button where it says abs bleeding procedure or w.e

any help would be greatly appreciated!!!

THANK YOU SO MUCH!!!

 

Here are WIS docs. Since you have Xentry you may have already viewed docs however, they may benefit other members.

 

What brand and type of fluid did you use? Post a part number or picture of bottle.

 

Just by chance, did you get the calipers mounted on the wrong side? Bleeder valve UP? Caliper appears to bleed correctly, but not really - lots of air remaining inside . OK, I thought so.

 

Did you take apart the brake MC at all?

 

Hi! I realize this is an old thread but as I’m having the same problem I’m curious to hear if/how you managed to sort this out?

thanks!
Anton

 

18 psi is not enough.
I had W210 who had very old brake fluid, making traction coming at freeway speeds, so I wanted it flushed.
I used spare wheel for building the pressure in the reservoir and even at recommended 30 psi, the fluid was just dripping.
than I pumped 35 psi and it start flowing.
Quite amazing but fluid reservoir holds the pressure just fine.

 

If reservoir level comes up after pumping the brakes it means either air in the system (lots of it) or something is making the brake pads retract from the rotors. In the long post from mjec515 he says he could see how the brake pistons moved and from his writing I understand he could see this more than once. You should see it only once when the pistons bring the pads to the rotors. The should not retract to be able to see them move again.

When I did both my S and E-Class I used a vacuum bottle system but it is the same as using pressurized system. Vacuum method only gives up to one bar (14.5 psi) maximum pressure difference thru the system but it seemed to work fine. What I did was after setting the fill bottle at the reservoir I set the vacuum hose to the bleed nipple and opened the bleed screw. Then with engine running I applied pressure on brake pedal slowly bringing the pedal all the way down. After 10 presses I took it was clean fluid running thru and with vacuum still on I could see clean fluid coming out even without pressing the pedal. Then repeated this for other three brake calipers. I think pressing the brake pedal with ENGINE RUNNING is important to get the ABS valve system properly flushed out.

This worked for me and resulted very firm brake pedals on both cars so there had to be some air come out from them both systems. This just tells me I should have done this bleeding way earlier.