92chevycorsicalt

I have a 92 corsics v6 with the engine off you can press the brake pedal all the way down butthere is a little resistance and the pedal comes back up, with the engine on the brake pedal is hard and there is a loud hissing only when brake pedal is pressed, I did have to fix a vaccum hose that was missing, could this be the booster g going bad or just a brake hose, I have a new master cylinder in her

GHOSTOWLGRID

If there is a loud hissing, try listening for it when the engine is running, it might be coming from the booster.
With age, they have been known to rust, possibly rupture.
Do you know where the hissing is loudest?

With engine off, if you keep pressing break, it should start getting harder to press each time. But the peddle will always come back up each time. There is a spring. The rest of it needs the engine vacuum to undo the hard peddle and to also make it easier to break.
When you start the engine, that should immediately go away, if not, the booster might be ruptured...
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Did you inspect all the other vacuum lines?
92 v6, I'm assuming you have the 3.1L MPFI v6. and I do know those lines get brittle with age. It is possible one might be broken somewhere and your breaks are fine.

If the breaks feel mushy, and you do not seem to be able to stop fast, there might be air in the break lines, they need to be properly bled out.
(I say this because you said the master cylinder was replaced)

Hope this helps.

92chevycorsicalt

I can press the brake pedal all the way with the enine off and not running

kevinkpk

X2. Try pumping the break pedal engine off, do you get any resistence/pedal?

92chevycorsicalt

To be honest no theres next to none and it never changes no matter how nany times I pump the oedak and with the engine running, the pedal is almost imposible to press

92chevycorsicalt

Ment pump the pedal

GHOSTOWLGRID

Okay What I am getting:
The peddle is hard to press.
It takes quite a bit of effort to stop the vehicle when pressing the breaks.

What I believe I see:
This happens with the engine on and off.
The Break Peddle does NOT fully travel to the floor and bottom out.

What I suggest based upon this:
Replace break booster.
It is the big thing the master cylinder bolts to with 2 bolts.
You might not have to disconnect the break lines from the master cylinder when doing this, There might be enough room.

Unfortunately I never had to remove a break booster before, So I can not tell you how to replace it.

It is up to you to take my advice, I suggest someone else on here give a post supporting or revoking this post of mine so the OP has more input from others.

Also, I have never had a booster fail me, I have only heard of them going bad, so because I've never experienced it, I can not be cretin I'm right.

BUT:
IF The Break peddle goes all the way to the floor or very close to it:
AND The vehicle feels hard to stop.

Then It is probably not the break booster failing. It is Air In the lines like I said above.
You will have to have the break lines properly bled if not done so already. Try doing it a second time, sometimes not all the air gets out the first time.

OR: You could be having a combination of both these issues...
I couldn't say any more unless I actually had the car in front of me and tested the breaks myself while looking it over.

Hope this helps, good luck.

kevinkpk

Did you bench bleed the master cylinder? If not, how long did it take to get the air out of the system?

GHOSTOWLGRID

And if you did this ^

MAKE SURE YOU DID IT RIGHT. lol
I went to rebuild a messed up master cylinder and it would not go back together properly and then it didn't work at all after that.
It used to be only half working.

I just went and replaced it. lol