The first thing to do is check for leaks in all four brake cylinders and along every brake line. Then bleed the system carefully. (Bleeding is a two person job.)
Start with the left front brake (closest to the master cylinder), then the right front. Once those are properly bled, do the rears.
If the fluid is brown or dark brown in color, it would be best to flush the system, because there's rust in the fluid, indicating that water got into the system. Every line and cylinder (including the master cylinder) will need to be cleaned until nothing but clear fluid comes through them.
If! there's no leaks in any of the brake cylinders or lines and bleeding did no good, it's probably the master cylinder. Usually what happens to them is the piston wears in the bore and the fluid bypasses between the piston and bore, so the pressure is reduced enough to make the pedal feel mushy or collapse to the floor when depressed. And the seals wear out exacerbating the problem.
You can rebuild them but it's probably easier to buy a new one.
The first thing I would do is loosen (don't remove!) the line(s) coming from the master cylinder and have someone
gently push the brake pedal (by hand is fine.) If fluid is not coming out in a steady stream, the master cylinder is likely bad.
It could also be a mechanical problem, although that's less likely. Have someone depress the pedal and see if the linkage is causing the plunger to move.
Even if you have to buy a new one, you won't be spending more than $100. Kit's cost around $35 or $40, but you've also have to own the hone. If you don't, that's probably another $15 or $20.
You can get one at
American Classic or
Jim Carter, two of our sponsors.
They both have repair kits, but you'd need to call them. Their websites don't say if they fit your master cylinder.[color:#FF0000][/color]
