'01 F-350 SD w/ PS. Just today, out of nowhere and with no warning, I applied brake and the pedal went to the floor! At first touch of the pedal it felt like there would be normal brake but immediately softened and pedal went to the floor. Still barely had enough brake to not hit somebody. Drove home (gingerly) and have been scratching my head. Fluid is normal.

What could it be? And how do I know?

 

master cylinder.
If there is no leak i can almost gurantee it is the master cylinder.
hope this helps
Billy

 

I found the problem (area). RR caliper has fluid running out of it. ??!!*^#!?

Is it possible that the pads can get so low that fluid leaks out of the pistons?

 

Same thing happened to me a few weeks ago.

Mine was a corroded metal brake line that blew out. The one that went to the rear.

Crawl under your truck and check it out.

 

it is possible for the rear pads to be so worn that the inside pad comes out and the piston exceeds its travel and leaks. I have seen it happen a number of times at work.

 

Well it's my lucky day. I get the truck jacked up and about to take tire off and it starts to rain! I'm a driveway mechanic. But I'll take apart tomorrow and find the problem I'm sure. Needs all new pads anyway.

 

you can get a rebuild kit for the caliper..if the piston poped out and was clean with no marks on it id at least do that...that would save a little cash..good luck...