Brake Problems, Now With Added Shifter issues!

[RustRocket]

Alright automotive veterans, I have a sort of strange problem. On my 82 Cutlass I've just replaced the front rotors, bearings, calipers, pads, and the rubber fuel line from hardline to caliper, on both sides. I've bled the front only, and the pedal has a very nice, firm feel when the engine is not running. When the engine is running, however, the pedal is spongy and very easily goes to the floor. Also, when pumping the brakes with the engine running, the red "BRAKE" light comes on intermittently and the revs die down about 2-300rpm when hitting the brakes. My question is, what have I done wrong? What else could the problem be? I know I haven't bled the rears, but would that really affect it in this way? Am I going to need a new master cylinder? A new brake booster? Please help me out as best you can, it's the final thing preventing this car from driving.
Thanks in advance

 

[theoldsone]

Sounds like somethings wrong with your vacuum to the booster. The only connection with the brakes and engine would be the booster...so id check out your vac lines and then the booster.

 

[pontiacgp]

Sounds like you might have let the master go empty for the front brakes. Try bench bleeding the master

 

[82GPLJ455]

Bleed the front some more,then bleed the rears.spongy pedal is air still in the system somewhere.the brake light coming on means there is an imbalance in the system,air or blown line.how are you bleeding it?

 

[pencero]

I already made this mistake too. It's not a 'problem' you didn't finish the job. Keep bleeding the brakes repeatedly and working the fluid through the lines until all the air bubbles are out. Theres air in the system somewhere. After you have both the front and rear bled and you do the process over a few times then go for a drive all the symptoms should go away. If it keeps happening check the inner edge of the wheel for brake fluid. If any of the inside edge of your wheels is wet w brake fluid you have a leak in the system somewhere. Keep checking the master cylinder to make sure it's continuing to work or your brakes could suddenly not work if it goes dry. You should see some of the brake fluid disappear from the reservoir if you bled the air out of the system properly and then you have to top it off again of course. Last but not least rubber does get old but if the thing in your reservoir is bad replace it. If it feels hard its not pliable anymore so its not really creating much suction even w/ the plastic clamped down.

 

[pencero]

Don't be surprised if in the process of bleeding the brakes a line sprouts leaks esp if it's stock or rusty. That's par for the course working w/ rusty cars. Put some clean cardboard under the car and if it has a leak little dark spots will appear where the brake fluid landed on it from wherever the leak is. If the cardboard does show a leak you should replace the lines.

 

[rustyroger]

I've come across master cylinders that go bad as soon as the brakes are bled. A couple of pushes past normal travel tears up the internal seal on a wear ridge and the pedal never comes good again. You are describing symptoms of the brake operating rod travelling too far and upsetting the booster.

Roger.

 

[pencero]

If you bled a rusty brake line towards an old master cylinder expect it to fail soon. Take it off and bring it in before buying new, there is usually a decent 'core charge' incentive since its a very important safety item.

 

[RustRocket]

I'm pretty sure I'll just get a master cylinder replacement, its 25-35 bucks so why not do it, it'll probably be better than the 30+ year old one in the car currently.
Thanks for the information everyone, I'll update again soon

 

[pontiacgp]

if you do get a new master open the box before you leave the store to make sure the kit to bench bleed the master is in the box.