is it normal when you press the brake pedal hard to hear an air like squishying sound (dont know how else to describe it) coming from the master cylinder. thats where it sounds like its coming from anyways. the brakes reallly suck right now

Brakes booster going south of the border master cylinder attatched to it .

Yes, the booster has a ruptured diaphram in it. It will get worse before it will get better. If you can't find one local at a yard I'll send you a good used one, $30 I pay shipping.

Aaron

One thing to check before getting a new booster. Take the check valve off and blow into the side that attaches to the booster. If you can blow through it, it is bad. I just switched mine out and my brakes are normal again.

Remember, air flow is through the vacuum tube to the check valve, and then into the booster. Make sure your blowing into the valve as if the air was trying to go back into the vacuum tube.

I'd hold off on a new booster for now. Is it the normal squish sound heard when you stomp on the brakes? Try it in a couple other cars, and I bet you will hear the same noise. It is normal. If the booster was leaking, your pedal would probably be rock hard (booster not working) Check a few other cars before throwing money into it.

Kris

EDIT: Also, if the booster was leaking, you would probably hear a vaccuum (sp?) leak from the booster area any time the engine is running.

[This message has been edited by shop_rat45 (edited 11-24-2004).]

I'd bet on a booster cause it is required to have max vac only when the brake is depressed. I'd buy a used one with the master attached.......less hassle. Good luck and peace.,

Phil

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I am always available to help those that need help. Since my back injury, I cannot work on many of the aspects of the cars, but I can offer the knowledge of my 27 years as a GM technician. Bring the questions on................!

A perfectly functional booster WILL make a "PSSHH" sound when you hit the pedal. If you had a bad diaphram, you would hear a hissing all the time, the Idle would be high, and the pedal would be hard to press. From what you describe, that's perfectly normal. In fact, try this, run the car at Idle, then shut the car off. Five minutes later step on the pedal, (the 5 minutes is to ensure that your booster still holds a vaccum, you could go on vacation for 6 months, come back and still have as much vaccum as before you left.) you should hear the "psshh" sound. let off the brake and push it again, it should make a much softer "Psshh" this time, and the pedal should not go as far as it did the first time, then press it again. the third time it might not make any psshh sound at all. Thats how a normal brake booster is supposed to behave. If it dosn't make any psshh at all, then you have either a bad booster, or the check valve on the front of the booster is not working.

if i press it when the car is off i hear a pshhhh

It takes one minute to pull the check valve off and blow into the side that attaches to the booster.

My brakes were acting like I didn't hav eany power brakes at all. Took all i could to get the car to stop rolling at 5-10 MPH.

After switching out the bad check valve for one I pulled off my parts car that was still good, they work perfectly.

If the valve doesnt keep the air in the booster, you don't have power brakes.

The pshhhhh sound is normal...a hissing sound is not. If it feels like you don't have power brakes that's not normal. If the idle increases when you hit the brakes that's not normal. If your pedal is hard that's not normal.

If any of the not normal things are happening on your car then replace the brake booster. It's really easy and you don't have to mess with the brake lines at all. Just disconnect the master cylinder and move it forward a little bit. You can put in the new booster and reconnect the master and you are good to go. Shouldn't take more than an hour or two at the most.

And by the way all Fieros use the same booster 84 to 88.

[This message has been edited by jscott1 (edited 11-24-2004).]

quote Originally posted by iwanna3.4dohc: if i press it when the car is off i hear a pshhhh

Trust me, that is a normal sound.

Kris