Is my brake booster bad?

deftsound

Please ask me how much my supercharger cost

Apr 6, 2004

945

1

39

Texas City TX

Apr 28, 2008

#1

• Apr 28, 2008

• #1

I have a brake problem, i cant stop the car and get brake pressure unless i pump the brakes a few times all the way up and down.

The pads are fine, master cylinder doesn't leak and is fine, all wheel cylinders are fine ...no fluid leaking anywhere, i think i have this narrowed down to the brake booster but am not sure..

how do i know if the brake booster is bad?

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

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Apr 28, 2008

#2

• Apr 28, 2008

• #2

The booster is there to assist your leg. When the booster is bad, generally you can still stop just fine but you have to push on the brake pedal like crazy to get the pedal depressed as much as your normally do.


If you have a strong leg and you are still having to pump the brake pedal several times in order to stop, that indicates a hydrualic issue. The MC can have a poor piston seal, so no fluid leaks externally but it also doesnt actuate the brakes like it should (just like how a bad ring seal on a piston would not show up as an external oil leak at the bottom of the motor).

I would reconsider the MC.

Good luck.

 

Prime Lord

Crappy Default Title

Founding Member

Sep 19, 2000

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Apr 28, 2008

#3

• Apr 28, 2008

• #3

+1 on the Master Cylinder. Pumping the brakes to get pressure is a sure sign it needs replacing.

 

Maryland Stang

Active Member

Aug 21, 2002

1,656

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Greenville, NC

Apr 29, 2008

#4

• Apr 29, 2008

• #4

Usually a bad booster will hiss when the brakes are applied. You would hear it.

I would simply try bleeding the brakes before I replaced anything. When you have to pump the pedal to get brakes that usually means there's air in the lines somewhere.

 

Mustang5L5

That is…until I whipped out my Bissell

Mod Dude

Feb 18, 2001

43,249

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Massachusetts

Apr 29, 2008

#5

• Apr 29, 2008

• #5

How does it behave when the car is off? I'm leaning towards bad MC. Pumping to build pressure is usually a tell-take sign

 

stykthyn

I want to measure mine. It doesn't look that tall.

15 Year Member

Jul 6, 2006

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gainesville

Apr 29, 2008

#6

• Apr 29, 2008

• #6

bad MC, I have had this happen on several vehicles. the rubber pistons on the inside break down and you wont get any pressure.

 

Maryland Stang

Active Member

Aug 21, 2002

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Greenville, NC

Apr 29, 2008

#7

• Apr 29, 2008

• #7

stykthyn said:

bad MC, I have had this happen on several vehicles. the rubber pistons on the inside break down and you wont get any pressure.

Click to expand...

Usually if that happens you'll get a fluid leak at the back of the MC when it meets the booster.

 

stykthyn

I want to measure mine. It doesn't look that tall.

15 Year Member

Jul 6, 2006

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gainesville

Apr 29, 2008

#8

• Apr 29, 2008

• #8

never had it leak from the back, but when I pulled the MC off and took the cups out you could see where the rubber was breaking down and the fluid would just flow around it.

 

Maryland Stang

Active Member

Aug 21, 2002

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Greenville, NC

Apr 29, 2008

#9

• Apr 29, 2008

• #9

Well, like I originally said, I would try bleeding the brakes first (since it's free) and see what happens.