ok my brake pedal has gotten real soft and my brake failure light has come on. i thought this was for air in the lines so i bled them. only to have no pedal change. i then replaced the master cylinder got some stifness back into the pedal but its still soft and the brakes work but they go all the way to the floor. now when i push the pedal i hear a air hiss. im thinking its the vacuum booster, am i correct in thinking this?

 

Good possibility.

 

doubtful//a bad booster will be HARD to push

 

thats what i was thinking. but i hear air hissing from the diaphragm on the column that the pedal push rod attaches to. and ive replaced pretty much everything but the booster and the hood was off for a long time maybe some rain got in there.....

 

but i dont wanna replace it unless necessary.

 

any other possibilities here argon?

 

A booster can not cause the red warning lite to come on...that means you have hydraulic problems...
you've done the m/c...have you looked for leaks?..i imagine your foot is "forcing" fluid out...a whhel cyl would be a good candidate

 

yea ive looked for leaks but dont see any anywhere. i havent had a chance to pop the drums off and see if its leaking inside. the pedal hasnt stiffened up much since the new cyl and bleeding the whole system. also i forgot to mention that those are brand new wheel cyls in there i had to do some brake maintance and ever since then it just hasnt improved.

 

On 89's..I have seen "dump-valves" cause this...its the exact symptom as a m/c....about all you can do is replace it.
I dunno if cheapies are available or not...I've not seen 1 bad in 10 years