Brake Job gone wrong.

Had my breaks checked. Brake Check told me it was the master cylinder
and front breaks needed replaces. I purchased new master cylinder and
replaced the old one. It went fairly well. I bench bled the new master
cylinder and had little trouble installing it ... BUT when I bleed the
system nothing goes well first a broken bleeder screw on my passenger
rear, I replaced the wheel cylinder. Then I bleed in the order
recommended by my Chiltons. Passenger rear, Driver front, driver rear,
passenger front. Things go well until I get to the driver rear. My
buddy pumps the pedal, holds, I open the screw, Fluid, I close the
screw, system pressure is crap. It is worse than before, almost no
pressure on the system. I start again and the same problem. I try and
skip the driver rear and move to the passenger from and I get the same
problem. I can get some pressure back if I just bleed the passenger
rear and driver front, but the driver rear and passenger front mess
everyithing up. No when I drive it I get some pressure, the brakes are
soggy and there is this "clump" when I press the pedal about halfway
through my braking. I can feel it in the pedal and the pedal jumps to
the floor. Any help is appreciated.

 

Assuming everything is installed correctly I would just gravity bleed
everything again.

CaptainKrunch

 

Just curious. Who did the brake check and why did you need the master
cylinder at the first place? Are you absolutely sure that you needed new
cylinder and brakes?

I'm a big skeptic of anything auto mechanics tells me unless I can verify
for myself. If they do brake checks, ask for actually millimeters of rotors
and pads using the calipers. I don't want eye estimates.. anyway... if you
were knowledgeable enough to tackle the brake job yourself I would reckon
that you know if it was truly bad or now.

Yeah... I would try to bleed it again. I have bought a long hose at a pet
store and routed it all the way to the driver seat as I pump the brakes ...
one man bleeding operation. At least you had a friend to help..

 

Have done same. A hose from cylinder bleed screw into a
glass jar. Then slowly pumping the brake petal, adding fluid
to master cylinder (so that it never goes dry) until brake
fluid is comes out clear. No need to close bleed screw if
hose is inside a pool of used brake fluid inside that jar.
Just press and release petal slowly. Also quickly identifies
an air bubble.

Furthermore, I agree with 'suspicion' of bad master
cylinder. They just don't fail unless brake fluid was
contaminated. Sound more like a brake line is clogged - again
contamination when someone refilled brake cylinder?

Sounds more like you now have air somewhere in the lines.
Get hose that is flexible enough to remain stuck on that bleed
screw. Use that jar so that you can discover when air bubbles
appear.

 

Thanks for all the help. The car has 185,000 miles on it. There was no
pressure in the lines with the old master cylinder and bleeding did
not help. It turns out one of my caliper mounts was siezed from any
movement so that wasn't helping. After cleaning up that mess I went
through the bleeding process again. I am able to get the pressure up
and the brakes work great, but I still have a problem if I open the
driver side rear bleeder screw. I lose all my system pressure. If I
bleed all three other lines I get it back. Very wierd.