2002 E320 brake issue
 

Brother replaced all 4 corners pads and rotors. Bled the system with new fluid. Everything was OK for the first few days now the pedal starts out firm but I can push it to the floor. Replaced the master cylinder with a new TRW one and the same thing. I'm thinking air in the system but my brother says no arguing that air would give a spongy feel not a firm feel. Would an ABS pump cause this? No indication of a fluid leak at the master or any of the calipers. The car stops straight so no indication of a frozen caliper.

He bled it the old fashioned way with a person on the pedal and arson cracking the bled screw. I told him to get a pressure bleeder and it will be so much easier and no chance of sucking air.

Any ideas?

Thanks

How do the flexible hoses look? Old ones can cause a bunch of interesting problems. I once let my 210 sit for ~3 weeks while traveling. Upon return the brakes were all mushy. Bleeding it addressed the problem, never to return. Another owner had a similar problem every spring after storing the car for the winter. It was due to very fine cracks in the flexible hoses. Replacing them fixed the problem for good.

This car is at the age where I just go around and replace all four flexible hoses.

I'll have him check but the brakes were fine prior to the pad/rotor replacement so I doubt that is it.

W211 with SBC SBC Brake Fluid Flush - Mercedes-Benz Forum

Anytime you can mash the pedal to the floor it points to a fluid issue. I would rebleed thoroughly, and if no results probably drop off at the dealer for the ABS/SBC purge.

Note that if you always (hot or cold) have a firm pedal with the engine off, the problem could lie elsewhere. Booster vacuum leaks often give rough running and codes as well. Also, some boosters have an oring/gasket at the master cylinder junction that gets overlooked when replacing the mc.

We are talking about a 210 here.

Good info to have. Then it's even simpler - don't worry about SBC.

Brother said there was no fluid by pass to the booster so as he saw. I'm going to suggest he re bleed with a pressure bleeder. At least eliminate that as a factor.

It's not a fluid seal, it's a vacuum seal. See picture (from W163).

Agree with the rebleed.

Did he open the bleeder screw on each caliper before he compressed the piston back into the caliper? That would just let the old fluid out of the system.

But if not, then that means he instead pushed a bunch of degraded fluid and debris back up the lines ... and potentially into the ABS plumbing. As you can imagine, this is generally not good. :(

If that's the case, you can and should try pressure bleeding, but this may end up being a very expensive brake job.

Good luck.

are you just opening the bleed screws as is or using a pipe n jar?

in using the pipe n jar the fluid should travel upwards from the bleeder. If going downwards or dribbling then you have a very high chance of air getting trapped in the calipers.

I had this on my W124. new brake flexible hoses, new fluid and a good bleed through fixed it right up.

Does it really start off firm, or do you have to pump the pedal a couple times to get it to firm up?

I would point out that a "pressure bleed" is no different than using the master cylinder to bleed. The whole purpose of the master cylinder is to generate hydraulic pressure for the purpose of actuating the brakes. It is quite an effective way to bleed. Pressure bleeders exist for speed, efficiency, and convenience.

I just successfully bled my 2004 E500 with SBC using a manual vacuum pump and a brake bleeder.
http://www.amazon.com/Brake-Bleeder-Vacuum-Pump-Kit/dp/B005BT90DI/ref=sr_1_4?s=automotive&ie=UTF8&qid=1411877393&sr=1-4&keywords=vacuum+pump+kit