Ok, Here is the story I have a 1999 F-250PSD 4x4 Super Cab. a little over a year ago the brakes started to act funny..I would be driving and the brakes would start to apply themselves It was like a claiper wasnt releaseing or something this went on for about 2 weeks then master cyclinder (factory) went out about 125,000 miles.. So I replaced the master cylinder with an aftermarket rebuilt one. All is well for about 3 or 4 weeks. Then it starts again. Brakes apply themselves. mostly drivers-side front. this is after driving 10 to 15 min on open highway, brake pedal has not been touched. after about 1 week of this the seal in the master cylinder goes bad. Repalce with another master cylinder. Same process good for about 2 or 3 weeks then brakes start to apply themselves. After the second replacement I did notice very high perssure in the brake lines. When the brakes would start to act up I could loosen the brake lines thd fluid would squirt about 10 feet. and the caliper would then release. I am now on my 5th master cylinder. The dealership has been NO help. What could cause pressure build up in my brake system? Im sure the seal in the master cylinder is the weakest link in the system so it goes first. Thanks in advance
CJ

 

could the booster be building up pressure in the system?