Well, I can, but I keep losing pressure in the brakes. What will happen is, I can press the pedal, and they are strong, but within an second or so, the pedal will drop to the floor, and the jeep will roll forward. I have blead the system a couple of times, and I know they are good. I am thinking that either its the M/C or the booster.
Also, when the pedal is droped to the floor, the brake light on the dash comes on and if I pump the brakes the light will go off and I can get a stiff pedal for a moment. but then it drops to the floor again.
any thoughts?
oh yeah, its an 85 cj-7 with a 258, power brakes, and disks in the front.

Sounds like the booster went south.

You might want to go ahead and replace the system with a hydroboost set-up so it'll stop those 40's when you get them on there :flipoff2:

Did you make any changes to the system before this problem accured? Did you do a break pad change or anything? it sounds like air in the MC to me. I do not see how it could possibly be the booster, that will just make the pedle pressure MUCH greater to get the same brake pressure will not make pressure bleed off. do you ever loose fluid? did you put in a new MC?

Your M/C is shot get a new one.. The only problem I have ever seen a booster cause is hard pedal when it goes bad just like when the engine isnt running..

I haven't done any changes to the braking system. I am also not lossing any fluid. I am gathering that the general thought the M/C is the problem. I thank you for your help and :flipoff2:

I also second the master cylinder. I've had a few go out on me on different vehicles and the symtoms were just like what you're describing.

Originally posted by hy_desert_4wheeler
Your M/C is shot get a new one.. The only problem I have ever seen a booster cause is hard pedal when it goes bad just like when the engine isnt running..


BING BING BING! We have a winner. Loss of pressure without a loss of fluid is an internal leak in the MC. The Booster will never cause the pedal to go to the floor.

Mastercylinder. If the booster was bad, the pedal would be hard as hell to push.

Originally posted by The Rockslut

The Booster will never cause the pedal to go to the floor.

I wish someone would've told my wife's Chevy that! They replaced the booster under warranty, we drove it another month and traded the thing off.