My brakes are acting up. When i stop, they dont have full braking power and the pedal eventually makes its way to the floor slowly. I have checked wheel cylinders and lines for leaks. I had doubts as to leaks in the first place due to the master cylinder being full. So there appears to be no fluid loss. Before i go off half ****ed and just started replacing parts, i figured i would ask here if anyone thinks it might be the master cylinder or something else?

 

Is the pedal solid when the truck is off?

If there are no leaks and all the brakes are adjusted properly, that would point to a booster and/or master cylinder.

Adrianspeeder

 

Yes brakes are solid when off.

 

Ok i went ahead a pulled the mc off and replaced with the one out of my red truck. I bled the brakes until i got good clean fluid out of all four brakes. I still have the same weak brakes. I take of the booster line and cap it off and the pedal is firmer but brakes are still weak. So i guess that rules out the booster. Even though i dont see any leakage around either wheel cylinder im begining to wonder if they need replaced. If they were bad wouldnt i still have good braking in the front? Im just trying to figure out why the whole system is weak. Please help? Throw something at me.

 

make sure ur drums are adjusted right b4 u replace anything. i was workin on a 94 bronco that some one changed the pads on and all of asuden had hardly any pedal wile runnin but had good pettal when off. drove me crazy tryin to figure it out but urned out the adjusters wernt adjusted right and the pads wernt contctin the drums

if thats any help to u

 

Thanks hillbilly. I have already checked the adjustment, pads, shoes, etc. I went out and tinkered with it some more and made a few phone calls. I drove down the alley behind the house and gave the brakes a good jab and the rears would lock up slightly (abs is working) but the fronts wouldnt even scratch in the gravel. My next check will be the front calipers and proportioning block. I also looked at the lines and i dont see or feel any obvious problems. I think its really pointing towards to front calipers but i dont know if that will have anything to do with the pedal feel.

 

Is all the air removed from the system? Did you bleed: Pass rear, Driver rear, Pass front and Driver front?
Did you pull back the front and rear boots on each wheel cylinder? If you see fluid, the wheel cylinder is bad.
Did you check for soft spots on all three brake hoses?

 

I didnt bleed it that order but im 99.9% sure i got all the air out. I went through half of a tall bottle of brake fluid bleeding these out and i heard the air come out of each brake. Tomorrow after all the Christmas day events i will re bleed in the order you suggested before i do anything else.

I didnt feel any weak spots in the lines.

How difficult is the booster to replace and are there any special tools required? I'm just about the point that im going to replace everything with parts from my red truck. Those brakes were perfect.

 

I rebled in the order suggested by blue07stx. No change. I replaced the booster, rebled. No change except i can get all brakes to lock with extreme, soft, pedal travel. My next step, i guess, will be the proportioning valve and then front calipers. I have rechecked the rear wheel cylinders for leakage, none. Any other ideas?

 

It could be frozen caliper.

 

I would like to think so but they do operate, weakly, but nontheless. Plus theres no drag.
i just replaced the wheel cylinders no change. Does anyone think it might be RABS?

 

Check your front brake lines where the banjo connector is on the calipers. If there is crap in the lines that is where it seems to pile up. That would be my $0.02

 

I have a similar soft pedal issue on my '94 F150. I have replaced rear drums/shoes, front pads, springs, cables, front hoses, rear hose and rear wheel cylinders. I have gone through several large bottles of fluid and I cannot get all the air out of the system.

When I start the engine, idle in (P)ark and depress the pedal; the pedal goes to the floor about half-way before resistance and then the pedal will continue to bottom out. I hear no audible swishing-air noise. The pedal is somewhat firm when driving but not as firm as it should be. The pedal will soften up a little more as I continue to drive.

Should I replace the Master cylinder or the Booster? Any ideas?

 

That is exact same issue im having. I cant get the air out of the lines. As much as I've bled them it should be free of air. A booster and mc didnt help anything. Shoes, pads, drums, calipers, wheel cylinders, all look great. I'm really starting to wonder about the proportioning valve for the rear brakes. At least thats what i think it is. Its bolted to the frame right underneath the mc and the line goes to the rear brakes. There is also some wires that come out of it and goes into the harness.
As far as something being clogged, i dont think so. There is just too much fluid comming out of the bleeder valves. I have now gone through two big bottles of dot3. As far as being sure i had all the air out i guess i was wrong. I can see the fluid bubble in the mc. Air is getting in the system somewhere. I have meticulously checked every inch of line and can't find any leakage or weakness. I'm absolutly stuck. Time to take ot to the shop i guess.

 

Ok random thought. The brakes have those little bleeder valves. What if the little ball on those valves were allowing air into the system? Is that possible to let air in when you push the pedal and not let fluid out?