Brake Mystery: New MC, fresh bleed, still no brakes!

[DetroitMatt]

Hi everybody, I had what started off as a rotted brake line in my 2003 X5 4.4i and it's turned into a nightmare. One of the hard brake lines under the drivers door had rusted though and started leaking. I cut out the offending part and patched in a new piece of factory hard line there. I tested it and it worked fine, other than the pedal traveled way to far before the brakes engaged.

I took it to my local German shop here in the Detroit area in hopes that they could put it into "bleed mode" on their computer to get out any air bubbles that may have worked their way in to the DSC unit. They were unable to get the pedal hard, and couldn't figure out why.

Frustrated, I replaced the master cylinder, because what else could it be? Between the shop and myself, we must of ran a gallon or two of fluid though there.

Master cyl replaced and the brakes are worse. I took it back to another German shop in the area and they say that I have good pressure coming out of the Master cyl, but hardly any coming out of the DSC / ABS unit. Only the front brakes are working and the rears are doing nothing. They are now claiming that it's the DSC / ABS unit (part #3451676545) and I can either get a rebuild kit for $2,500 or a new unit for $3K.... madness for a 10-year old car with 100K!

So I did some research and I found a used one that's been tested and warrantied for a year for a few hundred dollars, so I'm having that shipped to the shop for them to install.

Sorry for the novel, but that's my history. Now does anyone have any thoughts? This makes sense I suppose, and we'll find out once they replace the pump, but I think they're just guessing at this.

I'll let you know if it was indeed the pump, but anyone else ever experience something like this? Any one have a similar problem of the brakes just not being able to be bled?