Brake Pedal to Floor

[Lawyerjoe]

2012 825i. Stuck in a muddy creek last night. Another 825i pulled me out from rear. Then noticed brake pedal to floor. Emergency brake works fine. Brake fluid reservoir empty. Thought I cat a brake line, but no. Instead, left front brake assembly/housing nut was lose where brake line enters the housing.
Today I opened reservoir and filled to top with DOT4. I tried pumping brake and still to floor. I even opened right wheel housing to let som fluid run through.
Is there some trick to getting pressure back in the pedal.
I am a new member and searched the forums for other advice. Thank you.

[pcbunn]

Sounds like you have a leak some where else. You should do a complete brake bleed at each wheel and check each fitting. Buy the tech manual, it's worth it.

[Jake B]

I just replaced the seals in my master cylinder and had the same experience. If you drained the reservoir then you need to bleed the master cylinder before bleeding the rest of the system. Fill up the reservoir and leave the cap off, then pump slowly and look for air bubbles. This took me several minutes of slow pumping to get rid of the bubbles. Then move on to the wheel calipers. If yours are like mine, then you will see an upper and lower bleeder screw. Use the top one. Go around and bleed all the calipers two times.

One of these is a big help:

One Person Brake Bleeder Kit

Place the bleeder kit above the caliper you are bleeding. After pumping the brakes a few time, make sure to refill the reservoir. If it runs dry, you must start over. You will still need two people, one on the pedal and one at the wheel.

Mine is a 2006 HPX but the process should be the same:

Screen-shot-2013-05-18-at-8.57.48-PM.jpg Screen-shot-2013-05-18-at-8.53.16-PM.jpg

[Lawyerjoe]

Awesome Advice. It worked. Still can't figure out why they have upper and lower bleeders. Maybe there are two pistons. Thanks again!

[Jake B]

Just one piston. I think it make them universal (right or left).