89 4X4 Pickup

Both front brakes are building up brake pressure. Enough drag to slow the truck down. The pedal is at the top and hardly requires any pressure or downward movement to stop the truck. I can drive it but, I can feel the drag and smell the
heat from them. Some times, if I jam the pedal hard it will free-up just a little.
It seems to loosen over night but builds pressure again after driving a little.
I had replaced both calipers, rotors and pads in the fall. The problem started a few weeks later. I only drive the truck maybe 10 miles a week.

My mechanic said he released the pressure on the calipers by cracking the brake line at the MC. This tells me that it's not a collapsed hose or frozen calipers. He feels that it's the brake booster but everything I've read about failed boosters describes a pedal that is hard to push down in order to engage the brakes. Thats not what I experience.

The truck was new to me when I replaced the brake components. So I have no history on it. The master cylinder looks clean and might had been replaced not so long before I bought it.

Could the adjustment screw in between the MC and booster move on it's own and cause this problem?

Could the MC cause this?

Can a booster have these symptoms?

Any help appreciated?

Thank you

 

I would try adjusting the pushrod between your brake booster and master cylinder. If it is too tight, then the master cylinder will never let up all the way. The master cylinder was probably replaced and the rod was adjusted incorrectly.

 

thats where i would start also

 

mine is doing the exact same thing but all i did was rebuild the rear brakes everthing was shot i mean everything drums shoes hardware springs, parts missing it was nasty. rebuild everything but no air pressure from the rears no matter what i did. so we checked the master for pressure. it was good. so i thought i would drive it to see what it did. the fronts start dragging now after like 10 mins of driving. strange. then after 15 min it let go.

 

Problem solved. it was the push-rod it was all the way out! looks like when the p.o. had the t4r the rear brakes went out they adjusted the push-rod to "fix" the issue. That explains why right after i rebuilt the rear brakes now the pedal had less travel. so i messed with it last night and now it rolls effortlessly! check that Push-rod! its really easy but remember to adjust the brake light sensor also.

 

Ok, I've been searching all over the place and i'm still trying to find some detail about how exactly to adjust the pushrod. I see many people saying to adjust it. But no one has stated how exactly. As far as I gather, you will find the pushrod if you remove the mc...
Just looking for some direction before I take it off and get in there.
Thanks in advance for any help.

 

Try going under the dash to get to the pedal, disconect the pushrod from brake pedal, loosen locknut and spin the end of push rod. This in effect is to shorten the push rod to ensure it is releasing all pressure from master cylinder.