Master Cylinder Woes

[BeauJ]

I put new brake pads on 2 weeks ago, front and back, and now I have to press the pedal so hard to stop. Bled them twice, still nothing. I don't like to mess with more than pad on the brakes, so I took it to Just Brakes and the guys said the master cylinder was going bad. Now, correct me if I've heard wrong, but it doesn't just gradually go out, it just fails without warning? Also, what is the bleeder on the side of the master cylinder for?

 

[unclemeat]

When the master cylinder fails the brake peddle should go to the floor. Sounds to me, more like a vacumm hose or leak to the brake booster.

 

[exploded99]

The master cylinder has two pistons in it, one for the front btakes and one for the rear brakes. It is possible when bleeding the brakes to get the front piston ( the one for the front brakes) stuck in the bore of an older worn master cylinder.

To check: Push hard on the brake pedal with the engine running so you get full brake boost, and open a front bleeder. If the fluid dribbles out instead of shooting out, you are not getting pressure to the front brakes.

 

[Premier]

Yea, I had one just fail on me once... scariest **** ever!

 

[BeauJ]

I'm replacing it this week. But what purpose does the bleeder on the side of the MC serve?