I recently purchased a 98 outback the brake lines were so rusted they were leaking  in some places, I replaced the lines and the master cylinder, I primed it before installation,  bled the brakes the old way 2 men system, the brakes continue to go to the floor, I tryied the vacuum sytem and still the brake pedal keeps going to the floor,I don't see any leaks any where any sugestions I don't have much hair left to pull

I would bench bleed the MC again and start over. Remove the MC lines, replace them with some short lines bent back into the reservoirs and you don't have to remove the MC. 

What line section(s) did you replace? The rears from under the passenger rear seat to both rear wheels tend to be the ones that rust out. It could still be leaking above the fuel tank or somewhere back there if you didn't do the entire rear lines.

 

Having the pedal go beyond its normal travel i.e. to the floor is bad esp on older vehicles. Someone mentioned there is often rust in the master cylinder bore beyond its normal travel and that can cut up the seal 'cups' in the master.

I replaced the entire line from the master cyl. to the junction under the seat and the one from under the seat over the fuel tank to the rear calipers, I don't see a leak nowhere

 

 

the master cylinder is brand new, I used 3 pints of brake fluid to bleed using different methods and I primed the master cyl. before installation, it's just driving me crazy.

Did you bleed the calipers in the correct sequence? 

 

I want to start by thanking 
everybody that participates  in
this forum  you provide so much great
information and  encouragement it is
greatly appreciated, Well, finally fixed the brakes going to the floor on my 98
outback, after pulling a lot of my hair trying to bleed them I tried different
ways to no avail, finally asked a friend to help me and the first thing he
noticed was the front calipers were inverted the right one was on the left
and  the left on the right side  making the bleed valve being at the bottom
and impossible to bleed properly , once we reverted them and bled the system the
brakes started to work the way they are supposed to,  the moral of the story sometimes we are in a
hurry to do things that overlook small details with great consequences.