I just replace my stock 92 civic hatch master cylinder because the brake was sinking to the floor, it worked nice for a while but today driving I press the brakes and the pedal sink to the froor to the point you cant push the pedal any farther. I dont know what to do the only thing that I noticed at the time I chage the master cylinder was that the brake booster had rust were the old master cylinder leaked fluid. I took the booster apart, clean it, and painted it. it didnt look like the fluid damage any internal parts so I put it back with the new m/cylinder. like I said, it worked fine but now these happens. I got home all mad because I spent so much time replacing that S@#*. I pushed the brakes fast and hard a couple of times to relieve my anger and the brake started working again WTF. I dont want to drive the car until I fix these problem it might happen again and I could hit somebody. thank your help.

 

little more info: brake fluid reservoir is full, did proper bleeding, it is a new master cylinder from Honda. when I was driving before the brake sank, I felt like the brake calipers were grabbing a little without me pressing the brakes.