I would assume that it has Vacuum assist and not hydro boost.
The first place I would look is behind the master cylinder. The master cylinders are known to leak and sometimes the fluid goes inside of the booster.
If you never had your fluid system flushed, then I would believe that the old dirty fluid took out a couple of the O rings in the master cylinder.
If it is Hydroboost, I would pay careful attention to both the booster and the master cylinder. I would check the fluid level in the power steering pump and the reservoir. I would also look at the booster behind the master cylinder to see if there is a apparent drip or stain of fluid running down the front of the booster.
There is no gremlin that comes in the middle of the night and steals your fluid.
Normal fluid loss is attributed to a gradual wear of the brake components - pads and rotors. Most times you can find the leak on the drivers side rear, right in front of the wheel on top of the frame - if the line rusted out.
If the rear is disc brakes, chances are, that the calipers are not sliding on the pins and that the pistons retract when you leave off the brake pedal. When that happens, you usually have to have the mount rebuilt and you might have to replace the calipers if they traveled too far. Since there is a rubber boot that goes over the pistons - the pistons can fall out during inspection - if someone stepped on the pedal and if the person putting it back together just squeezed the piston back in place. Since you are there and I am here, there is no way for me to diagnose your problem over the internet without physically looking at the situation.
Now would be the time to take it to a garage and have it repaired.
Has anybody had a brake pedel go all the way 2 the floor.My wife came home and said the brakes were out. I do have 20 Budniks (very heavy).So I go 2 see and they sure were all the way 2 the floor.Checked master ,and the front was empty. NO ABS LIGHT AT ALL. I put fluid in it and it goes about 75% down before they start 2 work. Any idea? (booster, air in lines, ???) looked 4 leaks and did not find any. Also no fluid where it seats on concrete
