brakes work great than they dont. then work agian

[thepopeis1]

so I posted this a few mounts ago and did not get any help so one more try.

ive been having trouble with my 99 xplorer 400. the brakes work great the parking break can be left on hard for a few days at a time and still on strong. than all of a sudden when driving it there is no brakes. every time this has happened I pump the brakes like crazy for a few min. and nothing. than I give up let it set and magically 5 minutes later they work perfect again the rest of the day. This does not happen very oftion. maybe once every 5 hours of use. I'm just scarred to death Im going to be going down a hill or in some other really bad place not to have brakes and they fail.

Ive bled the brakes several times. I inspected all the brakes lines. all fine.

when i was bleeding the brakes last time. the master cylinder plunger got stuck down. and seamed identical to what it was doing on the trail. kept pumping and would not come back up it had to sit for a few min. So this is the only place I can think of to start. I'm just trying to decide if I should get a hole new master cylinder or just part # 1930799 witch is a new "plunger" with new gaskets on it and a new spring.

[cwlongshot]

That would be my suggestion... Your MC needs rebuilding or replacement..

CW