I recently had to hit the brakes hard (on my '03 f150 4x4) and in doing so heard a sound like when you prime the brakes after a brake job. Well.... now my brakes will stop me but my pedal slowly looses preasure and I have to keep pushing further to apply more stopping power. Right now I am approaching the floor with the pedal. What could this be? Would it have to do with my master cylinder? How bad would the bill be also? Thanks for any and all help.

 

Questions:

How's your brake fluid level?
If full; how does it look? Bubbly?

If that's the case you could have air in the system. With the pressure you described you could have a hole in a line or a cracked reservoir.

Check your brake lines from the caliper to the res. any leaks?

Sounds like intermittent pressure; which would make me think it's there's air.

 

Also; be careful- this can be a hazardous problem.

 

Came across this recently and it might help. Ford F150 Technical Service Bulletins by year. Might help?

http://www.ford-trucks.com/tsbs/?tsbmake=FORD

 

Thank you for the responses. The resivor is full, no cracks or bubbles in fluid. sprayed everything down with simple green under hood to degrease and washed down to try to find leaks, none found yet.

 

You blew out the master cylinder or the brake booster, apply brakes listen for hiss coming from the booster, you probably ripped the inside, my advise by the whole booster and master at the same time, don't forget to bench bleed the MS before Install, if you can't find a leak one of the two has gone bad, guaranteed. How many miles? Probably time for new anyway. Also bleed all the old fluid out of the brakes and put in fresh. Not a hard job and not expensive. Just did it.

 

110k miles is all. put new pads on over a month ago. about how much for the master and booster? If im able to do it then I will, hate taking a beating at a shop.

 

Replaced master cylinder and bled all 4 corners twice. Also crimped off front and rear lines seperatly to try to determin a caliper, no such luck problem still exists.

 

Abs hcu

 

Precisely.

https://www.f150forum.com/f6/brake-p...-150-a-157374/