Ford Repair Questions? Ask a Mechanic for Answers ASAP
Replace the front brake hoses. It sounds to me as though the interior of them have deteriorated over time and have gotten partially clogged. It is allowing the brake fluid to the caliper because it is under extreme pressure from your foot, but when the pressure is released the fluid cannot make it back because of the clog/restriction and thus the caliper will not release.
Well, that is what I thought it would be. I'll opt out cause I don't know what it could be.
The rod between the brake booster and the brake pedal is adjustable,sometime different manufacturers of master cylinders will slightly alter the specs on the adjustment rod depth, to compensate for re manufacturing tolerances especially if your master cylinder is an aftermarket reman unit. When the rod is too long, because of the altered adjustment, it leaves the brakes partially applied, also another scenario that can occur is for the master cylinder to be defective right out of the box, and not allow the return of brake fluid from the calipers. one of these two scenarios is at play here.
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Hello. I have noticed it's been a while since you have asked, so I will run an idea past you. You have definitely exhausted all the most likely possibilities including the RABS valve. You say that it starts after driving a few miles. So, does that mean that when you first start the truck and start driving, that it's fine? If that's the case I would look for a brake line that's possibly too close to an exhaust manifold, or other exhaust component, causing the brake fluid to boil. It may sound unlikely, but I have seen it before. Of course, NOT before spending a ton of time on it trying to figure it out.