Freddie

I have searched the forum re: brakes and read 20+ pages on W211's and SBC's.... but did not see a response to this issue:

My W208 needed pads and rotors so I changed them out. Reassembled and all seemed fine. After pumping pedal in the garage and backing out, brakes seemed fine. 1 mile down the road and the pedal went almost to the floor. Checked for any fluid leaks / cracked lines and there were none. Reservoir is full and fluid level visibly drops and raises after applying brakes. Bled the brakes (at the rotors) TWICE since then. After bleeding, pedal pressure was restored but at soon as I turned on the ignition, the pressure dropped again and the pedal dropped back down.

While driving, the first pump of the pedal shows very little back pressure, the second pump improves slightly and the third pump brings the pedal back to normal. Once pumped up three times in a row, the brakes do not seem to fade at all if the pedal is kept depressed. After the pedal is released it only takes about three seconds for them to lose all pressure again.

Any suggestions are welcome. Thx.

sosh

You are getting air in the system somewhere. I would recheck anything that you had apart and check anything that you disturbed with the pad install. Could even be a calliper that was damaged.

Freddie

Noone ever really replied to this one. Assuming that it was, indeed, just air in the system, I ran about 2 quarts of brake fluid through the system using a Motive Power Bleeder @ 12 PSI. After correcting the fluid level, pedal pressure was decent.... until I turned on the ignition. Pedal dropped to the floor again and required two or three pumps to regain adequate pressure.

I would be happy to replace the master but it almost sounds more like the booster. Master is readily available from many suppliers but booster might require going to the stealership.

I know people are hesitant to give brake advice on a forum like this but any insight would be appreciated.

StopTech

Have you tried flushing without the power bleeder? One person at the caliper and another at the pedal.

Freddie

I've tried both. Did the two person bleed first, then used a Motive Power Bleeder @ 12 PSI.

Had it to the local Mercedes tech and he bled them again. Same issues as before. He thought it was "brake assist module"... but his computer could not confirm the source. I even called local MB dealership and they confirmed they had a few BAM's handy (since it was a common problem). When I went to pick up the car, tech said dealership sent him the wrong part; CLK430 has an ESP but no BAM. He handed me the keys back and told me to take it to the dealership. I guess he was fed up too.

Tech warns me that you cannot remove the master cylinder or the booster without computer assistance. At this point, I am ready to replace both to get my brakes back.