Hello everyone!
I have a 2000 accord and the vehicle has 150,000 miles. The vehicle was sitting in my driveway for about 5 months because it needed a battery, starter and a alternator. I fixed the problem about 4 weeks ago and when I started driven the vehicle the brake pedal hit the floor and the vehicle just barely stops. I checked for leaks and verified if the master cylinder was top-off and every thing look good. I decided to bleed the brake system 2 weeks ago and I see a lot of air in the system with the vacuum pump I'm using for the job. I can't get the air out, I used about 7-8 bottles of dot-3 brake fluid and the air would not break for me. Also, last week I decided to bleed the master cylinder just to make sure there was not any air in it. So the master cylinder was installed with no air in it and I bleed the brake system again beginning from the front left, front right rear right and rear left in that order and the system stills has air in it. The brake pedal stills hits the floor.
Ok, so I really need some help here. Do I have a bad master cylinder, bad caliper's, bad rear wheel cylinder's or something else? The master cylinder stays top-off and I do not have to add any brake fluid in it.
What diagnostic test can I apply to figure out my brake system problem?

 

if the system does not have a leak then the master cylinder needs replacing and you want to replace the slave cylinder at the same time

try to put the pedal clearance the same on the new mc as on the old mc by making sure the pushrod length is the same

 

Ok, I'll replace my master cylinder, before I replace the master cylinder is there any way of knowing if the cylinder is the problem with all the air staying in the brake system? Also, I'm going to get a master cylinder from the junk yard, I know is a crap shot but at least I will not be spending a lot of $$ on parts and labor.