My brake pedal goes all the way to the floor. There are zero leaks. I have brake fluid and didn't lose any. I get a tiny grind sensation when first hitting the brakes, then they go to the floor and I have a tiny bit of braking left. This reminds me of the same sensation I had before when my brake line broke on a diff car. Im not sure whats wrong with it. Master cylinder maybe?

SOURCE: brake pedal goes all the to the floor. can not

Check the reservoir to be sure the fluid is full. If not, top it off and try it again. If there's still trouble building pressure, pump the brakes a bunch of times, and then check around each wheel for fluid on the ground. If you see none, it's possible that you have a break in the line somewhere through the chassis and that the fluid is leaking out inside. If you see no evidence of leakage, and the reservoir is still full, you need a new brake master cylinder - what will have happened is that the diaphragm around the plunger inside the master cylinder (which moves through the cylinder when you push the pedal, and forces fluid out to the wheels) has a hole or tear in it, so instead of pushing the fluid out to the brakes, the plunger simply moves through the fluid. It never builds pressure, and your brakes don't work.

Testimonial: "thanks for the info. very helpful. harry Newman"

SOURCE: Loosing pressure to brakes

Sounds like it is either your master cylinder, or a combination valve leaking. Unbolt the master cylinder and see if it is wet behind it in the booster.

SOURCE: fluid not gushing out brake line

sound like problem is in the combination valve.

SOURCE: brakes lines rusted on a 97 cadillac deville

Metal brake lines rust with age, become potted & leak fluid. Replace with copper pipe, is only marginally more expensive, the labour to replace will be the same but copper wont rust, so future cost saving & safety. Job is easy enough to do yourself, unscrew where it joins master cylinder, then follow line back, clipping it out from any securing clips, unscrew other end, coil up & take to motorfactors, ask them to make a copper brakepipe exactly like your old one, dont worry if you snap pipe during removal, take all bits with you so correct length can be gauged. Copper is very flexible & can be bent to shape when you refit. Make sure you have new brake fluid to bleed your system with after replacement.
Have fun.

SOURCE: it is leaking brake fluid out from under car where

see if the lines are loose the brakes are spongy because there is air in the line. tighten the lines and bleed the brakes.