Brake Problem

[cruizin70]

Recently I was driving my 70 Skylark when all of a suddenly my brake pedal felt like I had air in my brake lines and the car lost about 90% of its braking power. Whenever I step on the brake pedal not only does it feel like it has air in it but it makes a whooshing sound. The car would stop but I had to give myself plenty of room. Any sudden stops would have been impossible. I checked the brake booster valve and it was attached to both the booster and the intake with no leaks. The master cylinder was full of fluid too. I have no brake fluid leaks in any of the lines or wheels. I even tried to bleed the brakes but the braking power is still gone. My car has disc in front and drums in the back. Anyone have any suggestions as to what may be the problem???

[techg8]

master cylinder no longer functioning is what it sounds like. IE fluid slipping past the seals in the master cyl bore?

What kind of whooshing? vacuum leak whooshing or fluid slipping past seal squishing?

[cruizin70]

The whooshing sounds more like air than a liquid squishing sound. Plus the brake fluid is always full. So you would recommend swapping out the master cylinder first to correct the problem?

[techg8]

No. if its an air sound then the problem is in your power brake booster somewhere.

[GotTattooz]

No. if its an air sound then the problem is in your power brake booster somewhere.

Yeah, what he said. If you hear air rushing under the dash when you press the brakes, then the diaphram inside the power booster is torn and you need to replace the power booster.

-Josh

[cruizin70]

How difficult is it to replace the brake booster? Is it something I could do in my garage or should I consider taking it to a mechanic?

[1 bad gs]

you guys are on the wrong track. the booster is there for power assist. when the booster is bad you get a real hard pedal. change the master cylinder first.

[roboteq-1@hotma]

I'd still look at the booster- does your car get rougher at idle if you pump the brakes? if the booster is leaking internally this will act like a vac. leak. The booster is very easy to change- see if you can score an old one from the boneyard for testing- they are pretty reliable so a used one should give you an idea where you're at. If the booster did croak the symptoms are there.
Good luck
Robert

[cruizin70]

I did what you said about pumping the brakes when the car is park idling and I noticed that the idle gets rougher when I do this. RPMs drop from 550 to around 350 RPMs.