Ok, so my master cylinder was leakng, got one in good condition and replaced it. I bleed the whole system and the cylinder itself. When the car is off, there is alot of pressure in the pedal. When you start the car, the pressure seems to go away. You have to floor the brake pedal just to get the car to barely stop. And even with the leaking cylinder, you only have to press the brake down halfway just for it to stop. Whats the deal? Im thinking something to do with the brake booster? Any help please!

 

Sounds like you still have air in the brake system...

The powerbrake assist kicks in when the engine is running (allowing you to 'sink' the pedal)

Rebleed all 4 corners... if that doesn't solve it... faulty replacment MC.

 

Do you have ABS? The brake bleeding procedure is different for ABS.

 

Bleeding the ABS system is COMPLETELY different

 

I have re bleed the whole system about 3 times. That is why I am confident there is a problem with the power brake booster. Im thinking there is something special that needs to be done after changing the master cylinder, or should I jsut move to getting a new power booster? I believe 1MAX2NV had the same problem.

 

Rebleeding the brake system. I don't know if you have ABS or not. I don't. You suppose to bleed Passenger Rear side, front driver side, rear driver side then passenger driver side. The peddel suppose to be hard when the engine is off because the brake booster is not getting any vacuum. If this doesn't work, then you have a faulty MC.

 

Make sure you have all the hard lines to the MC tight. A little minor leak will suck air into the system.

 

I have non-ABS. So when you had your problem, it had nothing to do with the brake booster? I guess I can try bench bleeding the master cylinder and then installing it again. But I went through the process like 3 times already.

 

Eventually my brake booster broke also, but I believe my original problem was with the master cylinder. I would try bench bleed the MC before installing it. I'm looking into different method of bleeding my brake system now. I'm taking a brake system class at the local community college, so next time I will have more knowledge on the subject.

 

You can have a professional bleed the system. They have equipment that does a much better job by either using a suction type bleeder or a pressure vessel type bleeder. I made my own pressure bleeder.

http://forums.maxima.org/showthread.php?threadid=

 

I bled my ABS brake system last Saturday after I installed s.s. brake lines. I used a vacuum brake bleeding tool. When I got in the car to check the pedal, it went to the floor on the first press but stayed back up for each subsequent press. I then started the car and pressed the pedal and it went all the way to the floor again. The following strokes had the pedal at the normal position. You would think that there was still air in the lines, but I did NOT re-bleed the system and it never went to the floor again.

This is the third time I've bled the system since I've owned the car and each time it has done this.