What could be wrong with my brakes?

[80K5]

Whenever I put my brakes on and hold them on for a little bit they lose pressure and I am able to press the brake petal all the way to the floor. The lines aren't leaking and the master cylinder doesn't leak and is full of brake fluid. Does anyone know what the problem could be?

Stuck? Isn't that a bird!
Steve

 

[1979Jimmy]

Just a wild ass guess here but maybe there is gas building up underneath the bad when you apply the brake lifting the pad a little.

79 Jimmy, 5" lift 35 M/T with a 383 puttin out 400hp and 450lb/ft. Locked front and back.

 

[BobK]

I think that's a sign of a leaky booster.If you have one of those Mighty-Vac vacume pumps attach it to the booster and see if it will hold the vacume you apply with the hand pump.

<font color=green>BobK<font color=green>

 

[jimmyjack]

I'd be willing to put a few dollars on a bad cylinder somewhere. A bad booster just makes the pedal super hard and the brakes don't work. You could have a torn seal on the master cylinder or one of your rear cylinders is toast.

That jeep thing? Yah I understand it....... Like my Blazer? <a target="_blank" href=http://community.webshots.com/user/blazerk5>http://community.webshots.com/user/blazerk5</a>
Jim

 

[slider79blazer]

check the vacuum line going to the booster look for cracks or rotting. also the plastic valve in the booster that the vacuum line hooks to might be cracked.

<font color=blue>whats a 4 letter word for farm wagon?-- ford</font color=blue>

<a target="_blank" href=http://community.webshots.com/user/slider79blazer>http://community.webshots.com/user/slider79blazer</a>

 

[nofeartruckin00]

I had a bad booster a few months back, but it made the brakes really hard. Pull the vacuum line off the booster, then try stopping the truck.

Mud...

 

[moneypit]

Bad Master Cylinder.

 

[Triaged]

Bad master cylinder...
That is the only thing that can be a "internal" leak (it can leak back into the res. or get sucked into the booster vac. line...either way you won't see it.).

'71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
<a target="_blank" href=http://community.webshots.com/user/triaged>See it Here </a>