[cody mendenhall]

my brakes work ok when i pump pressure up with pedal but i lose pressure after a little while any suggestions

 

[Believer45]

Does the brake warning light in the dash come on when things are not so good?

I would look at bleeding the brakes, second thing to check would be the vacuum pump, third the brake booster.

Dave / Believer45

 

[blageurt]

Somehow it would seem that air has invaded your system . As Beleiver stated , bleed the system , replacing the fluid with new . If the pedal is hard, or gets harder when you step on it , the Vacuum pump is baked or you have a vacuum leak. Check fluid level and under truck at lines / wheels for obvious leaks. If level is OK and you have no leaks it is a booster / Master cylinder Issue. Disconnect the booster vacuum line to rule it out and if pedal is the same you have an internal master cylinder leak ,and you need a new one . . .

 

[cody mendenhall]

brake light does not come on and there isnt a leak anywhere my fluid level is always the same and i just bled it again today no air

 

[blageurt]

Master cylinder is where I would start. Just make sure you bench bleed it correctly before you connect the lines to get all the air out of it .

 

[Snowtow]

Classic symptoms of an internal leak in the master cylinder. Fluid gets past the seals slowly losing pressure.

 

[finallygotanIDI]

do you mean the pedal is spongy on the frist hit, or the pedal is hard then creeps to the floor if ya keep your foot on it

 

[realbadlarry]

First, fill out your signature so we know what year mods etc..The early trucks had a booster that would let the pedal drop to the floor under constant pressure..just the booster not really an issue. You can replace the booster if you don't like it or just learn to live with it.

 

[cody mendenhall]

it has good pressure at first if i pump it but in the last few months my braking has been terrible when i stomp on them with a trailer i lose pressure and they dont stop well

 

[cody mendenhall]

i filled out my sig

 

[blageurt]

When is the last time you adjusted your rear drums ? When is the last time you flushed your brake fluid ? Like ws mentioned previously , some early OBS models have the fading pedal syndrome, that is why alot of people who tow alot changed the system from vacuum boost to the hydroboost system used on the early superduties and chevy diesels. Big difference in pedal feel when this mod is done . . .

 

[cody mendenhall]

rear drums were adjusted about eight months ago and fluid was changed then too

 

[ryhed]

Check for ever so slight leaks at the rear wheel cyllinders.

 

[cody mendenhall]

alright i changed my master and there is no improvement what is my next step?bench bled my master and bled my brakes about 5 times when i step on the pedal now it goes 3/4 to the floor until i get brakes

 

[Transman]

Check the ABS accumulator on the inside of the left frame rail. They have sent more mechanics and DIYs to the fridge for a beer than you think. Ford offered a test bypass tool that will plug right in and you can leave it there.
Good luck.

 

[Excavator]

rear drums were adjusted about eight months ago and fluid was changed then too

OK , first thing would be to adjust the rear brakes again. It only takes about 2 clicks in the adjuster with these rear brakes and you feel it better in pedal.

8 months is along time when it comes to these rear adjusters and it might have beed adjusted on the loose side 8 months ago