spongy brake pedal after bleeding
Thread Starter
Super Member
Joined: Feb 2015
Posts: 733
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From: USA
09E350, 07E63, 13CLS63
spongy brake pedal after bleeding
Done the bleeding many times before without any problem but not so lucky this time. When I first opened the bleeder, it turned back close by itself. I thought something get stuck so I kept pushing the brake pedal hard. Maybe the one of the seal got damage? I though maybe there were air trap inside so I did all over again, 2 more times in 1 week. There were no air bubble found both times but the spongy brake pedal is still there. I checked the brake lines and calipers and did not find any leak. Is there anyway this can be repaired?
Last edited by dustinN; Feb 24, 2026 at 05:26 PM.
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Are you pointing at the master cylinder piston seals gone defective after bleeding?
That's very possible if you squeezed hard on a long pedal with too much travel caused by open bleeders. Sometimes MC leaks inside the vacuum booster.
That's where vacuum or pressure bleeders come in for no-pedal bleeding.
That's very possible if you squeezed hard on a long pedal with too much travel caused by open bleeders. Sometimes MC leaks inside the vacuum booster.
That's where vacuum or pressure bleeders come in for no-pedal bleeding.
Last edited by CaliBenzDriver; Feb 24, 2026 at 07:40 PM.
Thread Starter
Super Member
Joined: Feb 2015
Posts: 733
Likes: 64
From: USA
09E350, 07E63, 13CLS63
Are you pointing at the master cylinder piston seals gone defective after bleeding?
That's very possible if you squeezed hard on a long pedal with too much travel caused by open bleeders. Sometimes MC leaks inside the vacuum booster.
That's where vacuum or pressure bleeders come in for no-pedal bleeding.
That's very possible if you squeezed hard on a long pedal with too much travel caused by open bleeders. Sometimes MC leaks inside the vacuum booster.
That's where vacuum or pressure bleeders come in for no-pedal bleeding.
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Are genuine MC rebuilt kits available ??
You can throw in a new set of flexible stainless steel brake lines to replace aged factory rubber lines.
Last edited by CaliBenzDriver; Feb 25, 2026 at 12:29 AM.
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From: Fleriduh
W212 E63S Wagon - GSL580 - E63 - E350 - C300
Lets look at reality...if they worked well before you bled them and now they dont...well, you did it wrong and have air in the lines (easy to do). You need to properly bleed the breaks...then, rock solid.
Thread Starter
Super Member
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From: USA
09E350, 07E63, 13CLS63
Yes, know i did not do ít correctly. I used the new one way valve, in theory there should not be any air trap in the lines. I wasted 3 littlers of fluid to bleed ít again and again. The problem is i dont know how I messed ít up. I did not see any air bubbles when I bled ít. I found a couple clips about bleeding the air out of the master cylinder. Maybe there is air tráp in the master cylinder. I would like to try this but dont know how to do ít on our cars.
Last edited by dustinN; Feb 25, 2026 at 10:59 AM.
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I've used the Motive pressurized bottle that connects to the brake fluid reservoir method on 3 of my cars a couple times without any problem. This is the method MB prescribes in WIS/ASRA.
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R170 230, w204 200, w212 200
Brake master cylinder
Hello, same thing happened to me, i tried to bleed the brakes on my w212 and after doing so the brake felt spongy, re-bled them multiple times with a pressurized pump but nothing, tried with xentry in the abs module but that only pumped it up and the brake pedal felt normal at first but after pressing it 2 times it was soft again. I ordered a new used brake cylinder pump and today it arrived, I will replace it and i will come back to this forum to tell you if it fixed my issue or not.
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R170 230, w204 200, w212 200
Spongy brake
Im here to update everyone following the thread, after i changed the master brake cylinder and bled the whole system again, the brake did improve but it still doesnt work as it used to, I took the car out on a test drive and when the pedal is pressed it slowly goes down and when pressed again it builds pressure (as it should), when slamming the brake pedal (eg. Emergency braking) its hard as a rock. The only time the brake pedal is soft/spongy is when being pressed for the first time. It could also mean that the master brake cylinder i bought had worn out seals but nonetheless it still works better than with my old master cylinder. Im not ready to buy a new brake master cylinder since they cost upwards of high 3 to low 4 digit figures...
To the reply above me, the w212 doesnt have sbc, only the w211 had sbc and it was such a complicated and unnecessary system that mercedes just scrapped it after using it on one model, but thank you for telling us to check wis, I will do that and report back in some time if i find anything..
To the reply above me, the w212 doesnt have sbc, only the w211 had sbc and it was such a complicated and unnecessary system that mercedes just scrapped it after using it on one model, but thank you for telling us to check wis, I will do that and report back in some time if i find anything..
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
race to fixed
Im here to update everyone following the thread, after i changed the master brake cylinder and bled the whole system again, the brake did improve but it still doesnt work as it used to, I took the car out on a test drive and when the pedal is pressed it slowly goes down and when pressed again it builds pressure (as it should), when slamming the brake pedal (eg. Emergency braking) its hard as a rock. The only time the brake pedal is soft/spongy is when being pressed for the first time. It could also mean that the master brake cylinder i bought had worn out seals but nonetheless it still works better than with my old master cylinder. Im not ready to buy a new brake master cylinder since they cost upwards of high 3 to low 4 digit figures...
To the reply above me, the w212 doesnt have sbc, only the w211 had sbc and it was such a complicated and unnecessary system that mercedes just scrapped it after using it on one model, but thank you for telling us to check wis, I will do that and report back in some time if i find anything..
To the reply above me, the w212 doesnt have sbc, only the w211 had sbc and it was such a complicated and unnecessary system that mercedes just scrapped it after using it on one model, but thank you for telling us to check wis, I will do that and report back in some time if i find anything..
That means the issue is on the car side not the MC itself, right?
Then back to: one of the wheel has an air bubble. Whole system has been bled 3x...
When / How did serious air get in??
> PLAN B: do not use the MC at all to pump during wheel bleeding.
Use a different method: either pressure or vacuum?
note when air comes out.
Last edited by CaliBenzDriver; Feb 27, 2026 at 06:52 PM.
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R170 230, w204 200, w212 200
If I understood correctly (?) small to no improvement with a second MC, right?
That means the issue is on the car side not the MC itself, right?
Then back to: one of the wheel has an air bubble. Whole system has been bled 3x...
When / How did serious air get in??
> PLAN B: do not use the MC at all to pump during wheel bleeding.
Use a different method: either pressure or vacuum?
note when air comes out.
That means the issue is on the car side not the MC itself, right?
Then back to: one of the wheel has an air bubble. Whole system has been bled 3x...
When / How did serious air get in??
> PLAN B: do not use the MC at all to pump during wheel bleeding.
Use a different method: either pressure or vacuum?
note when air comes out.
Last edited by Merc Benzz; Feb 28, 2026 at 08:14 AM. Reason: Information
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From: Colorado
G550
it didnt make a difference if the engine was running or not, on the old mc pump the brake pedal always felt spongy (it was going down quickly and it wasnt building pressure), on the new mc pump only the first time when the brake is pressed it is spongy and it builds up resistance on the 2nd or 3rd press.
very big improvement with the second mc pump because this time i can actually brake, it could still be the mc because i bought it used... air got in because i brought my car to a friend to change the brakes but he just took of the caliper and left it to stay for a couple of days which is eventually how im assuming air got in. I forgot to mention but i already tried to bleeding them with pressure but barely any air got out.
no you did not read OP's post, i am not OP, im just another member of the forum with the same issue. I also see you complaining that i bought a used mc, would you like to donate over a thounsand dollars to me so i can buy a new one?
very big improvement with the second mc pump because this time i can actually brake, it could still be the mc because i bought it used... air got in because i brought my car to a friend to change the brakes but he just took of the caliper and left it to stay for a couple of days which is eventually how im assuming air got in. I forgot to mention but i already tried to bleeding them with pressure but barely any air got out.
no you did not read OP's post, i am not OP, im just another member of the forum with the same issue. I also see you complaining that i bought a used mc, would you like to donate over a thounsand dollars to me so i can buy a new one?
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From: Baltimore County, MD
'13 s212 63 p30. '06 LX470
Op, You have air in the system...
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G550
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2023 E63S Wagon
... air got in because i brought my car to a friend to change the brakes but he just took of the caliper and left it to stay for a couple of days which is eventually how im assuming air got in. I forgot to mention but i already tried to bleeding them with pressure but barely any air got out.
https://mbworld.org/forums/w212-amg/...t-numbers.html
Here’s a PDF from WIS
https://mbworld.org/forums/attachmen...660d1620788318
From this thread:
https://mbworld.org/forums/e-class-w...lp-please.html
Good luck! A caliper removal shouldn’t cause this much hassle. There’s probably air somewhere. Maybe bite the bullet and have a dealer bleed it.
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From: Baltimore County, MD
'13 s212 63 p30. '06 LX470
Yes, I buy only new cars, but I keep them for a long time and conscientiously maintain them. I did a full brake system rebuild on my '95 Jeep this past year -- new MC, new pads, new rotors, new rear shoes, springs and cylinders -- everything except for the brake lines and front calipers, which I inspected. And all new parts. In total, maybe not quite the cost of of a MB MC, but still $$ in parts and my time. People seem to overlook that their poorly maintained cars create a hazard to other drivers. It's not just accepting the consequences that impact you.
Ive never bought a new car, and never had a safety issue. A well maintained car is achieved many ways. All my cars are kept and drive as new. Zero rust on my 20 year old truck (nice to see you keeping a nice old vehicle on the road) and zero maintenance needs. On many older vehicles, new is not available, and used is better than aftermarket.
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W212 PFL E63 (Weistec SC), F-350 King Ranch 6.7 HO, Yukon Denali, VW Atlas
I didn't read every response here but I dealt with something similar. I took my calipers off my car for a month while I refinished them. When I went to put the car back together, I bled each corner with my pressure bleeder and it worked great. Only problem was, my pedal would sink to the floor when the car was on. Long story short, I had air in my ABS pump. My Autel scanner couldn't talk to my ABS pump so I bought one that could. Well that didn't work either. So I tucked tail and limped my E63 to the nearest Mercedes dealer. 40 mins later (and $325 poorer) my car was perfect. Sounds like you have air in the ABS pump.
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From: Colorado
G550
I think you missed my point.
Ive never bought a new car, and never had a safety issue. A well maintained car is achieved many ways. All my cars are kept and drive as new. Zero rust on my 20 year old truck (nice to see you keeping a nice old vehicle on the road) and zero maintenance needs. On many older vehicles, new is not available, and used is better than aftermarket.
Ive never bought a new car, and never had a safety issue. A well maintained car is achieved many ways. All my cars are kept and drive as new. Zero rust on my 20 year old truck (nice to see you keeping a nice old vehicle on the road) and zero maintenance needs. On many older vehicles, new is not available, and used is better than aftermarket.
MBWorld Fanatic!
Joined: Oct 2019
Posts: 5,154
Likes: 1,769
From: Colorado
G550
I didn't read every response here but I dealt with something similar. I took my calipers off my car for a month while I refinished them. When I went to put the car back together, I bled each corner with my pressure bleeder and it worked great. Only problem was, my pedal would sink to the floor when the car was on. Long story short, I had air in my ABS pump. My Autel scanner couldn't talk to my ABS pump so I bought one that could. Well that didn't work either. So I tucked tail and limped my E63 to the nearest Mercedes dealer. 40 mins later (and $325 poorer) my car was perfect. Sounds like you have air in the ABS pump.
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Joined: Feb 2015
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From: USA
09E350, 07E63, 13CLS63
For a piece of mind, I took the car to the dealer and let them flush the brake fuid. Luckily, nothing broken, there are still air trapped inside, changing the fluid was all I need. I did this job many times before but I messed it up this time. Just because its a one way valve doesn't mean it won't suck the air back. Thank you all.
Last edited by dustinN; Mar 7, 2026 at 01:20 PM.
