I just replaced both a leaking master cylinder AND a leaking power brake booster. Yep I bled the master cylinder and brakes properly. (I usta be a mechanic.)
However, I've never run across the current problem I'm having. The front brakes keep getting tighter and tighter the farther I drive it. How can I tell? From the burning brake pad smell, smoke, and heat from the front wheels.
After sitting overnight the brakes are ok, or if I stop, shut the engine off and pump the brakes slowly to bleed off some of the vacuum.
I did not do anything other than replace the master cylinder and power brake booster, no brake work front or rear. The hydraulic brake system is still in balance front and rear.
Any thoughts on this situation?
Hawk

 

OK, I agree it sure sounds like the front brakes are not bleeding when you release the pedal. That would make me look for any way that the master cylinder is being held forward as long as you had vacuum on the booster.

#1 are the linkages adjusted to the same length old and new? I replaced an old booster years ago and about went through the windshield first good stop I tried. It turned out the booster had an adjustment screw so the pushrod was longer than original. Made it all really touchy. Could an extension of that cause your symptom?? Or is the pushrod not in the little dimple in the MC making it act longer? I know, not likely.

#2 Defective booster causing same?

I wouldn't immediately expect the MC as the system releases when vacuum releases.

 

Well, no idea if 2wd or 4 wd so I have no idea if this applies .... but a aged brake hose can sometimes develop a flaw inside that leads to blockage when pedal pressure is released and this blockage will hold brakes applied some .... and while a 2wd truck maybe has two, one each side .... a 4wd has those plus a third single hose from frame to frt axle.

Just a thought.

 

Leaky check valve... regardless if it is new.

 

Well, whaddayknow, I pulled the power brake booster loose and measured the pushrod length, comparing with the old one, as best I could without much success. So, I threw caution to the wind and turned the plunger adjustment in (shorter) by one full turn. Problem went away! That was over a month ago! Fuel mileage improved (never will be great tho) and I don't get any more hot brake smell or smoke!
Hawk

 

Thanks for the update!

I just did a swap of booster and MC myself and I did check the pushrod length .... but some how I just didn't think of that in your case .... but re-reading your initial post .... it's a description of the very symptoms it would cause.

 

Glad it was an easy fix in the end. Thanks for the update!