Brake problem/no leaks/no pressure
 

87 base model-Thinking its my master cylinder, car has all new pads and rotors. No leaks, pedal just wont hold pressure, it will if you pump it up, but then it just goes to the floor after about ten seconds.

you're prob 99% right, it's most likely the master cylinder. my sisters honda was doing the exact same thing. switched out the cylinder, good as new :-)

john

When my master cylinder went that's what it was doing. They are cheap if you find it used, I paid $35.

My brothers did the same thing and it was the master cylinder.

well i kinda have the same problem.. the pedal stays hard if you mash it but if you hit it lightly(like under normal driving) it will creep to the floor.. any ideas?
Dave