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Pedal goes to floor when turned on


NAXJA Forum User
Hi all, I've been having an issue with my 89 4x4 4.0 5 speed Cherokee since Changing out my master cylinder. It started off with replacing it because there was a slow leak on the rear port caused by cross threading. The brakes worked decently while leaking. I took the line off to replace the damaged brake fitting, couldn't find one that night so I put it back on and the brakes went to the floor, where my problem first started, I thought no problem there's just a lot of air in the system.
Since then I made a new line, bench bled the master cylinder and bleed over half a gallon through the system and the brakes still went to the floor. I've read threads since then and have installed both front calipers, rear wheel cylinders drums, rotors, pads front and rear, a 3rd master cylinder a 2nd line for the one I replaced. Basically everything new except brake lines and booster.
I see no leaks anywhere, with master installed and ports blocked the pedal is rock hard and doesn't drop, bleed countless gallons through the system with vacuum method, gravity method, 2 man method. I see no bulging in the brake lines but I think I should replace them anyways to rule out and they are old.
Thank you for reading such a long post but I feel I have tried everything I can think of and am stumped now.