Brake issues on a Chevelle Malibu 1976

[gagnon1s]

I have a 1976 Chevelle Malibu Classic that I can't seems to get the brakes to work right. The brake light on the dash comes on. I tried to bleed the breaks both front and rear but I still have a soft brake pedal.

[inafogg]

will the pedal pump up?whats been done... brakes ok?
i'd try & bleed the master cylinder,what kind of pressure do you have when bleeding
does it stop the car,are the rear brakes adjusted properly,are the drums/rotors with in specs?

[gagnon1s]

will the pedal pump up?whats been done... brakes ok?
i'd try & bleed the master cylinder,what kind of pressure do you have when bleeding
does it stop the car,are the rear brakes adjusted properly,are the drums/rotors with in specs?

Yes the Pedal will pump new front brakes rear are drum I believe they are still good.
I tried to bleed all the brake lines but I still have a spongy pedal.
The car stops you just have to push the pedal down a lot.

[Tony Silva]

Disconnect the wire (I think it is light brown) on the master cylinder. It is a (residual)pressure switch if your light turns off then replace the master cylinder. If your light still stays on then check the switch button down at the emergency lever. The button is located at the top of the mechanism near the e-brakes "teeth". This wire is also brown in color. Both of these wires are the negative ground side of the dash board brake light. If every thing is intact, take a test light and ground the alligator clip poke the probe into the at the master cylinder wire and then again at the emergenc brake wire ...but be sure to leave the wires connected while you do the testing. As for the soft pedal issue, I agree with "inafogg" when he say's to bleed the master cylinder. Bleeding the master cylinder is different than bleeding the brake lines.

[inafogg]

if you can pump the pedal while its running & get a good firm pedal than its probably air in system.not a hard system to bleed but you may want to start
bleeding at master cylinder,air can get trapped there.
you need to pull all 4 wheels & check linings,wheel cylinders calipers
if a drum/rotor is too thin it will heat up causing glazing hot spots in linings,drums,rotors causing poor pedal & braking

[gagnon1s]

Thanks to you both how do you bleed the Master Cylindar?

[inafogg]

Originally Posted by gagnon1s

Thanks to you both how do you bleed the Master Cylindar?

bleed it the same way you would bleed the front or back brakes
instead after helper pumps & holds brake pedal open the front line
to the master,bleed/close.do this until no air is present(front & rear brake lines to master cylinder)

[Tony Silva]

Go to an autoparts store and ask for a master cylinder bleeder kit...they are so cheap (less than 5 bucks). And you can bleed them yourself with no helper. what you do is basically: disconnect the hard lines and attatch rubber tubes and route them back up and into the master cylinder fluid. You pump the pedal and look at the tubes for air...the tubes are made of clear rubber.

[mdcamaro]

When you bleed the master, the lines must be submerged in the brake fluid in the master cylinder.

Then bleed left front, right front, left rear, and last right rear. The bleeder valve needs to be closed while the fuild is mid stream.

If you use a bleeder kit on the wheels, the line in the bottle needs to be submerged in the brake fluid. This prevents air from being sucked back into the system.

[gagnon1s]

Ok so I have bleed the breaks in this order right rear, left rear, right front, left front. I also bleed the master cylinder. I did all of this with the car off. when starting the car the pedal went soft and it is still soft. I don't know what else to do. Reading this car has disk brakes in the front and drum brakes in the back. It also has a power booster that connects to the master cylinder, could that be bad? Or would it be the Calipers in the front?

[mdcamaro]

Ok, I hope you are doing this with some help. You bleed the master first. then the next closet wheel to the master and finish at the wheel farthest away from the master.

You need someone in the car to pump the pedal untill it will not pump. (If you can not get the pedal to this point you have a fluid leak in the system.)

At this point you keep the pedal depressed. Then the person at the bleeder vave will release the valve. The trick is to close the valve before the pedal hits the floor. Once the pedal hits the floor repeat.

If the person in the car pumps the pedal while the bleeder valve is open, you will suck air back into the brake line.

To check the booster, after running the car pull the hose out of the booster you should hear a rush of air because you released the vacuum insde the booster. Also if you have your foot on the brake pedal when you start the car you should feel the pedal move as the booster pulls a vacuum.

Disk brakes or drums are the same.There should be no fluid visable on the rotors or the backing plates. No fluid under the master on the fire wall etc.

[gagnon1s]

Ya the pedal is always spongy and never really gets hard. I was told to bleed the brakes from the rear forward. Why are you saying from the front forward? What could be wrong if there is air in the line? Could the calipers be bad? Master cylinder problems? What are your thoughts? The car is 3 hours away so it will be awhile again till I can look at it.

[inafogg]

Originally Posted by gagnon1s

Ya the pedal is always spongy and never really gets hard. I was told to bleed the brakes from the rear forward. Why are you saying from the front forward? What could be wrong if there is air in the line? Could the calipers be bad? Master cylinder problems? What are your thoughts? The car is 3 hours away so it will be awhile again till I can look at it.

you may want to buy a brake bleeder they are about $30 & make bleeding much easier.

if you are still getting air when you bleed the system & there are no leaks then your master cylinder is internally pumping air into system
replace master & bleed the system.

[mdcamaro]

The idea is to chase the air out of the system. You need to keep moving the air further away from the master untill the last of it is gone. Air compress easily compared to brake fluid. So when you step on the brake you squirt air down the brake line like blowing bubbles through a straw. Think about squeezing a balloon vs a golf ball. That is why the pedal is soft. Now if you keep bleeding the system and cannot get a hard pedal you have a leak which keeps sucking air into the system.

[Tony Silva]

ebay gots a master cylinder bleeder kit for $12.99...I got one you can have for free. I know you can go to a shop and get the entire system "power bled" inexpensively. And this will COMPLETELY wipe out any questions of the system. If you are not too mechanically knowledgeable, maybe you should bite the bullet and pay a shop to do the work. I believe that the brake system is the single MOST important thing on a car. Your safety and that of the one's riding in...as-well as the people around your moving vehicle are worth it.