I am having a little problem with the brakes on 76 deville. the problem is that it wont brake. I have checked the master cylinder and it does not appear to be leaking fluid and the cylinder is full. I replaced the rear wheel cylinders(both) and attempted to bleed the brakes. I managed to get the air out of the rear brake lines(so I assume) and the little brake sensor light(the one that lets you know the is air in the line) cut off. now when I attempted bleeding the front brakes, sometimes the brakes would stiffen and sometimes the pedal would go all to the floor. what should be my next step? how do I know if the problem consists in the power booster?
alright. Does the pedal go softly all the way to the floor and not do anything? do the brakes finally kick in when you slam on the pedal as hard as you can? how does the pedal feel? too hard, too soft?
most of the time it feels real soft, but after a couple of pumps it gets hard and the brake indicator on the dash turns off.
Hmmmmm. And you said you've bleed the brakes? Try bleeding them again. I had the same problem with my Z when i changed the master cylinder. I had to bleed the brakes like 5 times before it was back to normal and the pedal stayed consistant.
To check the Brake booster, with the car off, pump the pedal a few times and it should get really hard. the pedal should travel the same distance each time and not vary. hold the pedal to the floor and turn the car on, and it should soften up and you'll notice it. depress the brake pedal and turn off the engine. hold it down for 30seconds . the position shouldn't alter.
I would agree with the Nail Man that you probably have air in the lines. If the master cylinder ran dry at any point you will need to bench bleed it. If not bleed bleed and bleed again. Make sure you follow the proper rotation to bleed them. Also the proportioning valve can get funky on these cars and cause similar problems. With the engine running hit the brake pedal a few times as fast and as hard as you can. This will sometimes get the valve recentered and get you going again.