I have a 2000 F-250 SD Diesel and Im getting a sponge peddle when I brake, and when I turn the steering wheel as I brake the brake peddle goes up and down. And when sitting still and only applying little pressure on brakes, I get a pulsing effect. I have bled the brakes and power steering, the power steering pump is new, and so is the hydro booster. there is also a hissing sound uder the dash when the brakes are applied. I have tried alot of things that have not worked .Any information would be greatly appreciated!

 

How do the brakes feel when the engine isn't running? It should be firm. The pedal should hold steady and not bleed down. If it does, then you could have a bad master cylinder.

 

Thanks muester for your reply. the peedle doesnt go away any. It was just a kind of a spongy feel, and you had to push kinda hard to get a peddle and then the trucks braking responded slow as far a stooping right away. But let me tell you what happend yesterday. Me and my brother changed the power steering pump again because of a sound it had when pushing the peddle. Well when I drove it after that as I would apply the brakes or if I were turning sitting still or at a slow rate of speed it was like I had no powersteering, but the brakes were perfect. And as i drove it a little longer the brakes went back to pulsing as you turned the steering wheel and the easy steering came back. So Im just kinda confussed I seem to either have it one way or the other!