Sound from power booster??
Thread Starter
Drifting
Joined: Oct 2001
Posts: 1,444
Likes: 4
From: Hawthorne NJ
Sound from power booster??
My '89 Coupe daily driver has developed a "squooshy" sound when you press on and off the brake lightly while parked. It may do it also while driving but I can't tell. It has a sound of pressure or air leaking while it's parked and if you tap the brake pedal on and off it produces this "squoosh" noise. The brakes work fine, it's not low on fluid, the pads are good. Could this be first indications that the booster is going?
Anyone experience this before?
Anyone experience this before?
Race Director
Joined: Oct 2001
Posts: 19,653
Likes: 428
From: Melbourne Florida
Cruise-In IV Veteran
When the booster on my 93 went out it made a wooshing sound but, more importantly, I could hardly push the pedal down it was so hard and could barely get the car to stop...
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
The booster is supposed to make some noise.
It draws air in from the footwell, and is pretty quiet unless you listen for it. If your brakes grab well, and the engine doesn't stumble when pressing the brakes, then it's fine.
It draws air in from the footwell, and is pretty quiet unless you listen for it. If your brakes grab well, and the engine doesn't stumble when pressing the brakes, then it's fine.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
The booster is supposed to make some noise.
It draws air in from the footwell onto the backside of the diaphram, and is pretty quiet unless you listen for it, or push the brake pedal down quickly. If your brakes grab well, and the engine doesn't stumble when pressing the brakes, then it's fine.
A leaky booster will hiss continuously when the pedal is being used, or maybe only certain ranges of travel.
It draws air in from the footwell onto the backside of the diaphram, and is pretty quiet unless you listen for it, or push the brake pedal down quickly. If your brakes grab well, and the engine doesn't stumble when pressing the brakes, then it's fine.
A leaky booster will hiss continuously when the pedal is being used, or maybe only certain ranges of travel.
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Drifting
Joined: Mar 2002
Posts: 1,251
Likes: 2
From: Thomson Georgia
I agree with Vader. The pedal movement will produce a little noise, but when you release the pedal or movement stops, you should hear nothing. The slight noise you hear is the chamber losing and gaining volume. I doubt you would even notice it.
If you're hearing the hiss, booster is going out, especially if it were loud enought for you to hear above the ordinary noise of the car.
If the vac check valve were split, you would have a hiss all the time and the pedal would give a bit more stiff from the vac leak. That's the plastic piece that pushes into the front side of the booster that the vac line pushes onto.
The 89 began hissing under light pedal pressure, pedal didn't stiffen on me, that's in the last stages of life, or a sudden failure. Pedal did begin to feel a little mushy tho'.
I bought my replacement about 3 years ago from Advance for around $140 or so. Don't even remember who made it, lifetime warranty. OEM will probably set you back twice that.
There's a steel replacement made, around the same funds as Advance, single diaphram like stock.
A dual diaphram is made, like the ZR1, it will give you more apply pressure with the same pedal pressure.
Life can vary from days to months, no way to tell.
If you want to check for sure, disconnect the vac line going to the booster and plug it temporarily. crank the car up and see if the hiss has gone away. I still say if you can hear it, it's bad.
Johnny
If you're hearing the hiss, booster is going out, especially if it were loud enought for you to hear above the ordinary noise of the car.
If the vac check valve were split, you would have a hiss all the time and the pedal would give a bit more stiff from the vac leak. That's the plastic piece that pushes into the front side of the booster that the vac line pushes onto.
The 89 began hissing under light pedal pressure, pedal didn't stiffen on me, that's in the last stages of life, or a sudden failure. Pedal did begin to feel a little mushy tho'.
I bought my replacement about 3 years ago from Advance for around $140 or so. Don't even remember who made it, lifetime warranty. OEM will probably set you back twice that.
There's a steel replacement made, around the same funds as Advance, single diaphram like stock.
A dual diaphram is made, like the ZR1, it will give you more apply pressure with the same pedal pressure.
Life can vary from days to months, no way to tell.
If you want to check for sure, disconnect the vac line going to the booster and plug it temporarily. crank the car up and see if the hiss has gone away. I still say if you can hear it, it's bad.
Johnny
Last edited by johnnyevans; Oct 16, 2005 at 10:06 PM.