I have a 95 Monte Carlo..the brakes "went out" on me several weeks ago. Everything checked out ok..so we changed the master cylinder. Things were fine for a week..then they went out again...we bled them AGAIN...they worked...few days later...out again...the brakes have been bled from the wheels and under the hood, master cylinder has been changed...still no brakes! HELP!! Any ideas/suggestions?

 

I had a similar issue with my 87 Dodge Diplomat (Dippy). I chased this issue for over a year. I would change a component in the brake system on Dippy and it would be fine for days, weeks,months. In desperation I changed out the pads, shoes, front calipers, front brake hoses, rear wheel cylinders, the rear brake hardware, and the master cylinder a few times. I knew that it wasn't the booster and if it had not been such a pain in the butt to change I would have done that too. It turns out in my case that the proportioning valve was faulty. I could not get a new one. I had to get one at a junk yard. I had also bleed my brakes multiple times too. In your case I would look at the proporsioning valve or the ABS controller that is next to the master cylinder.

 

when the brakes "go out" are you losing fluid? is your fluid contaminated? did you bleed the system properly?

if you already haven't, check all of your brake hoses/lines for kinks or cracks or leaks. check your calipers and make sure the pistons will compress, that they aren't seized. pull off your rear drums and check to see if your wheel cylinders are leaking or locked up.

 

When they "went out", did you here/feel anything from the ABS system?? I had a '93 Grand Am that the ABS system was very unreliable. I disconnected the wires on the brake booster that operated it and drove the car happily with non-ABS brakes and a ABS Brake light lit up on the instrument panel.

As stated above, any lose of fluid?

Even if one brake seized, the car should still stop (but you may feel one side or the other pull a little).

 

You have like no brakes at all or the pedal is hard and you have to almost push it to the floor? If its hard then I would check my brake booster

 

ok...there has been no fluid leaking..no noise...just have to push the petal completly to the floor to get ANY brakes and then pretty much it just slows to a stop...

 

I do have to push it all the way to the floor...not hard at all...

 

Based on your description, I assume the brakes feel soft or spongy?

If so, re-bleed. The way you may have bled the lines could have allowed air into the system.

I know you said you guy bled the system until it was clear/new fluid coming out. Sometimes this crap happens and you need to re-bleed or something went wrong (such as the person in the car did not do there job right).

Bleed process I've used (one person in the car, another at the bleed screw, work one brake at a time):
1 - Have the person in the car pump the brakes 3-5 times.
2 - On the last pump of the pedal, the person in the car should hold the pedal to the floor (until otherwise instructed by the guy at the bleed). With pedal down, the guy at the bleed opens the screw. A combo of air/fluid may come out.
3 - While the bleeder is open, the person in the car may note the pedal went closer to the floor, this is fine. While the bleeder is open they MUST NOT lift the pedal (or else you suck air back in the system). The bleeder only needs to be open for a second, then close it. Once closed, the person in the car can release the brake pedal.
- Repeat from step one about 2-3 times per brake (or until you get nothing but a steady stream of fluid). Make sure to keep the brake fluid reservoir topped off between every 2-4 attempts of opening the bleeder (otherwise, you may start sucking in air again). Do NOT bleed with the cap/lid off the reservoir.

Extra tip: Get a bottle (like an old pop bottle) and a clear vinyl/acrylic hose (a hose that fits on the fitting end of the bleed screw just past the hex head your wrench uses). This will prevent you from making a brake fluid mess everywhere. Also, I know people who recommend having some fluid in the catch bottle and the hose in the fluid, this way if something happens and the system tries to such in, it will suck in brake fluid and NOT air).

Hope this helps.

 

Is there a air sucking noise like a vacuum leak sound?

 

It sounds like there is still air in the system. The stuff maniac (Jason) said is good advice and I would like to add start at the farthest wheel.