Lack of Brakes!

[brutesque]

Ok, I was noticing my brakes were spongy and everything, so I asked around and decided it was the master cylinder. My pedal wopuld go to the floor, etc. So I replaced the master cylinder. And before I bled the system, I wanted to see how the brakes were doing, and they were doing the same thing. Slowly go to the floor with kind of a squealing sound. I figured that maybe I needed to turn the car on for it to work, and the pedal went to the floor with zero resistence.

So I bled the system. And nothing has changed except my filthy brake fluid is now more clear with the addtition of fresher fluid. The brakes dont work at all.

I had someone push the brakes and I narrowed the squealing sound to the tube that comes up from the brake booster, where it meets another. That SEEMS to be where the noise is coming from. But I could be wrong.

What could this be?

This is my daily driver, and Id like to be driving her again =(((

[MikeW]

Vacuum leak?

[brutesque]

How can I fix it? replace tubes..??

I am a total noob at auto repairs.

[zbane]

Would you post some photos of the master cylinder and mark where the noise seems to be coming from?

Also, do you have the Factory Service Manual for your 82 zx?

I believed it can be found at carfiche.com

[Walter Moore]

A vacuum leak would make the pedal harder, not softer... but that would make a noise...

I have had a LOT of old cars, and this sort of problem has happened to me many times. Sometimes it is just a bad master cylinder, but more often that not it has been a ruptured brake line. If a brake line ruptures, the pedal will go to the floor, but the car will still stop because the other circuit will continue to work.

You should look for signs of leaking fluid everywhere that the brake lines run. If you can get the car on a lift, with the wheels off of the ground, or at least jack stands, have someone hold the pedal to the floor and see if you can rotate any of the wheels. That might lead you in the right direction.

I have also had a brake failure warning switch (Directly below the master cylinder on the fender) develop a crack in the body and leak all the fluid from one circuit of the system.

The brakes are a closed hydraulic system, and it doesn't take much of a leak to render them inoperative. I suppose that even a severely blown seal in a caliper would cause a problem.

By the way, it is possible to bleed the brakes on a car with a leak in the brake system. I have done it more than once.

[brutesque]

Well, I can hear some kind of squeal-ish sound coming from the hose that comes up from the booster on the side closest to the outside of the car, that connects to a hose leading to the engine. There is a metal connector thing that connects them, and they are held to the body of my car with a bracket. black hoses, about an inch in diameter.

I dont think Im leaking fluid, Ive never noticed low fluid levels.

I have the Haynes manual, no factory book. There is a possibility the metal thing making the noise is the brake check valve??

The squeal is fairly quiet, I cant hear it with the engine running.

[beandip]

The thing you are referring to is a one way valve in the vacuum line to the booster. Did you bleed the master before you installed it? Another thing did you take the booster off the car or did you by chance pull the rod out that comes out of the booster, that activates the master? If you have pulled on the rod in the booster , this is the problem. there is a disk that the rod rides on that is in between the rod and the diaphragm . If the rod is pulled forward the disk falls out and from then on the peddle will go to the floor. Gary

[brutesque]

I did bleed the master cylinder before I put it on.

I may have pulled the rod. I think I bumped it, but it looked fine, not that I really checked. So I would just have to put the disk back in place? That might be it...

[brutesque]

Would the rod/disk thing not work when the car was on, and wok when it was off?

Cuz thats whats happening.