1997 blazer brake question

[Kain]

I have a friend that her booster went out on her blazer, thats what the mechanic said thats what i thought
so i showed them how to change it. it was 50 % better but still hard as hell to push in the pedal and i am stumped on what to do to fix it.

i bledd the brak fluid by hand to get the nasty fluid out thats never been changed. and before i did it had no pedal after it was rock hard.like before just not as bad.

next question what is the thing on the fender and could this cause the issue?

 

[snowdriver]

That thing on the fender I believe has something to do with the abs system,if it were somehow malfunctioning,it would cause a hard pedal,are there some electrical plug ins on it you can unplug??

 

[Kain]

ya i will give it a shot and see also going to check vaccum readings

 

[diesel4me]

Old rubber brake hoses can harden up or clog inside and cause a hard pedal,with little braking action,as can seizing calipers or wheel cylinders..seeing the fluid was cruddy,its possible those 2 things could be the cause..I've also seen steel lines build up rust inside and nearly seal themselves shut ..

 

[Kain]

Old rubber brake hoses can harden up or clog inside and cause a hard pedal,with little braking action,as can seizing calipers or wheel cylinders..seeing the fluid was cruddy,its possible those 2 things could be the cause..I've also seen steel lines build up rust inside and nearly seal themselves shut ..

thanks ive talked to her and she says it will stop at slow speed 20 and under but 45 50 it wont stop.I am at a loss as what to do was going to pull the tires off nd check the caliper to see if it is stuck. but i am at a loss truly

 

[Kain]

the valvle that connects the boster to the intake had a bad oring have to get a new one in the morning, there was no vaccumm at the booster

 

[diesel4me]

"There's yer Problem"...no vacuum ,that'll do it..

One quick crude test of a power booster is to run the engine,step on the brake pedal,and note the effort required...then shut it off,and depress the pedal again,it should feel the same--after one or more additional applications,the pedal will "go hard" as the vacuum remaining in the booster gets used up..

If it feels hard on the first pump,either the check valve in the vaccum supply hose isn't holding,or the booster has a bad diaphram and cant hold vacuum--usually you can hear a hissing noise with the pedal applied when that happens,and the idle will be affected when you apply the brakes..