Hi guys, I have 96 super duty. The brake pedal goes to the floor while pulsating slightly. The brakes are grabbing a little but as the peddal hits the floor I can barely stop. It has a hydraulic booster. I am trying to pinpoint what to replace before I take it apart. The booster, the master cylinder, or the power steering pump. It does steer good so I am leaning towards that not being a problem. Thanks in advance.

might be as simple as the brake pads just are sticking. have you changed the brake pads recently?

my dad has a 95 F150 and whoever had it before him changed the pads and idk what kind they were but the would do virtually exactly what your saying.

450 superduty

I didnt change the pads but I don't think it is the pads, I am leaning towards the master cylinder leaking internally. Thanks

oh... wait i missed some of what you was saying. i didnt catch the brake pedal going to the floor.

yes your right youve got a leak somewhere..

The problem is that the brake fluid tank is full. Nothing has leaked out of the system that is what makes me think it is bypassing within the master cylinder.

hmm. thats wierd. that does sound like its not holding pressure. so it would be internally leaking.

powersteering fluid full? No whining when turning?
assuming its diesel
Ive never really messed with hydroboost, but ill see if i can help ya

Diaphram in that might be f-ed, usually that causes hard pedal. But i have seat it go the other way



Lastly, the seal might be bad in the master cylinder, but its really wierd for your to be dropping the pedal and then it grabbing right at the floor. and still have a full resevoir.

The two times (yes twice) that has happened to me ive blown out a caliper.

You absouletly sure its full, not dirty and seems full?

Ps
Try bleeding your brakes. you know pump it up. hold pressure break the bleeder screw ope, look for bubles. then close it and repeat, make sure you dont have any air in the lines.
makes sure teh brake fluid isnt foaming, it could cause that issue.

Finally
I did have a issue similar tot his, kinda, they topped it off with antifreeze and blew out the seals