I just bought a used 99 E320. Unfortunately, it has no brakes. The pedal goes to the floor with or without the engine running. I checked for leaks and I found none. I tried to bleed the system but with another person helping me there was very little fluid coming out of each bleeding valve during pumping. The fluid level in the reservoir was at max. I didn't see any air coming out too. Is this a symptom of master cylinder gone bad or something else is wrong ? Does anyone know the proper procedure for bleeding the brake system including the ABS pump ? I purchased the tool needed for bleeeding under pressure.

 

Yesterday I replaced the master cylinder and the problem is fixed. I’m very surprised that after 103 K miles in a car like Mercedes the master cylinder went bad. I have another E320 from 1998 with 128 K miles and have no problems with brakes. I used pressure bleeder with 29 PSI pressure to bleed the system. Bleeding the ABS pump I did by loosing up each line that comes out of the ABS pump. Ignition switch On, engine not running. Now when I step on the brakes they are hard like a rock. My next project on this car that I have for today is to find the leak in the power steering system. I found a spot of the power steering fluid on the floor.

 

Hi, I hope you can still get this post. I was wondering if you had any issues getting the master cylinder out of the vehicle. I'm trying to do the same job, and I just can't get the master to come out of the brake booster. It seems like something is holding the cylinder to the booster. I've taken off the bolts, unscrewed the lines, and no matter what I do, I just can't separate the two. Any help would be welcome! Thanks!

 

Not sure.. the master cylinder does just pull out of the master cylinder. should be 2 nuts holding it to the booster. pull on it harder theres nothing to break.
maybe try to remove the vacuum line attached to the booster maybe vacuum is holding the master cylinder. be careful not to break it.

 

Thanks! I have everything disconnected, but I'll try again now. There isn't anything else that would prevent pressure from reaching the calipers right? I'm not sure if that gigantic line block near the master cylinder could prevent pressure from reaching the calipers, but I checked 3 of of them and there was a LITTLE bit of pressure when the pedal was depressed all the way, but it wasn't even enough to do a manual bleed of the brakes.

 

Got it out. Just needed to move some other stuff that was resisting it out of the way. After getting it out I could test it and it failed. Thanks to everyone.