Nissan Repair: auto, nissan premira, disc pads

Question
QUESTION: my 96 nissan premira has no brake. the pedal is spongy and flooring. everything checks out. what could be the cause of that?
Thanks.

ANSWER: Roshella,

If the pedal is going to the floor it usually means the master cylinder is gone.  That is, you have brake fluid in the reservoir and there is no fluid leaking at any of the four wheels. Use a quality DOT3 fluid to bleed the system after the new master cylinder is installed.

---------- FOLLOW-UP ----------

QUESTION: I just changed the brake lines and the disc pads. the master cylinder was fine prior to that.when turn on the car the pedal goes strait to the floor. to get a little brake i have to pump the pedal repatedly?

Answer
Roshella,

If the brake lines and pads were changed and then the brakes were bled that could be the problem.  If all air has not been purged from the system that could be the soft/no pedal problem.  You need to have someone press the pedal, engine running, and then have another person open the bleeder screw at the farthest back wheel.  Press the pedal and have then open and close the bleeder to prevent air from re-entering the system.  Then, repeat the process until clean fluid comes out.  Repeat this at each wheel making sure to keep the fluid full after bleading each wheel.  Do not let the fluid get too low as air will reenter the system and you will have to start over.  Now, if all of this was done and the pedal is soft that would mean the master cylinder needs to be replaced.  If you bleed brakes the pedal goes down further than normal.  This usually will trash the seals in the master cylinder and that is the most common cause of needing a replacement cylinder.  It is nothing anyone did it just happens due to the piston running in an area it has not been...