failed master cylinder?


New Member
New guy here. Sorry for the lack of intro. I'm at work.

My ex g/f called me as the brakes on her 09 Focus SE failed.

I assumed she'd ran the pads into the rotor, but the fronts still had plenty of meat on them. (at least 50%).
The fluid was a murky gray, the pedal has very little authority-- and slowly goes to the floor. Hoping that she'd cut a line, or maybe one had rusted I had her come out and push down the pedal.
IT bubbled (air) into the brake fluid reservoir. I assume failed brake master cylinder, but I've never seen one blow air into the reservoir.

I tried briefly to bleed the fronts, but the bubbling continued as I made attempts to do this on the fronts (Yeah, I realize you'd start from the passenger rear-- but I think the problem is the MC, not air in the lines).

Is there anything special I need to know about replacing the master cylinder, or any tips from someone who's done one on this? Looks like it should be pretty easy to get at, once the battery, and maybe that fuse box are out of the way.

Thanks in advance



New Member
Has anyone here replaced one. It looks like if you remove the battery (done) and can shift the main relay/fuse box (loose but not moving much) it should be very accessible.

I've removed a screw at both ends, and slid the outside (fender side) of it off a metal tab. It looks like removing the battery tray so the u-shaped battery bolt (that holds both sides down) will work, but the bolts holding it (and the battery tray) in place are rusted. I hit them with PB blaster and will check on them, likely tomorrow, when the new master cylinder arrives.

Any tricks to getting the reservoir hose off the master cylinder?


New Member
I'll be doing a write up (post facto) of the replacement. I took a few pics putting it back together. I did learn a few things that would be helpful to know if you end up replacing one. :(