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AZTechBrian
AZTechBrian, ASE Certified Technician
Category: Ford
Satisfied Customers: 708
Experience:  Owner
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Ford F-350. All kinds of brake work done. But the original

Customer Question

Ford F-350. All kinds of brake work done. But the original problem still occurs. After new rotors, bearings, calipers, pads, master - after a few miles of driving, my brakes appear to be partially applied. The front brakes are hot. The stealing is stiff. Calipers are red hot. Can you please help?
Submitted: 1 year ago.
Category: Ford
Expert:  Mike S. replied 1 year ago.

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.

Customer: replied 1 year ago.
They've been replaced. When calipers were done. The only thing that isn't new is the vacuum assist. I also have a proportioning valve on the frame. (Not sure of name)
Expert:  Mike S. replied 1 year ago.

Well, that is what I thought it would be. I'll opt out cause I don't know what it could be.

Customer: replied 1 year ago.
Dang.
Expert:  Cardoctor71 replied 1 year ago.

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.

Expert:  Cardoctor71 replied 1 year ago.

Please rate my service a 3 or above, if for some reason you can not ,please ask me another question, I will continue to answer your questions even after rating is given until you are completely satisfied with my answers.

Customer: replied 1 year ago.
I had already adjusted the booster rod. I called my local ford dealer, (a service manager is s friend), he advised me that it was the rabs valve. Replaced the valve. No difference. The brakes get a residual pressure as I drive. Steering gets stiff. I can feel the front brakes on. Proportioning valve on the side of the master cylinder?
Expert:  AZTechBrian replied 1 year ago.

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.