Ford: ford f-150 brakes 1998, ford f 150, bleeding brakes

Question
We have replaced the master cylinder following step by step instructions and after bleeding brakes repeatedly it still only has a half pedal. Back brakes are adjusted out properly with new shoes.

Answer
Hi.


the best way to check where the problem originates is to pinch off the front and rear brake lines.  If the pedal is good ( remember that the pressure exerted can fluid push past any pinch off device if pushed hard enough), then remove eadch pinch off one ata time until pedal drop is felt. then examine and adjustor rebleed that assembly to correct.  If the pedal still drops while all wheels are pinched off, the the master cylinder is at fault.  

When bench bleeding, be sure that the plunger was not depressed too far, as that can cut the cups on the holes in the bore. about 1" max should be enough, or have some one press the pedal and measure the amount he rod moves out of the booster and match that measurement.

and, yes, bench bleeding is a must.  Bleed until bubbles stop appearing.

Also, master cylinders can sit on the shelf for long enough to not work whenn it comes time to be installed. We have often gone through 1, 2 even 3 or 4 before we get a good one.