Bad brake booster ?

[blackazz]

What's up turbo guys.just wanted to see what symptoms do you get with a bad or leaking brake booster? Installed a leed brake bandit did great the first couple days now it just runs an dont shut off.after reading there fourm it says I might have a bad booster.what test can be done to see if it's the booster?thanks

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[TexasT]

I'm not sure what a leed brake bandit is. Is this a power master unit? Some other booster like a vacuum setup or hydroboost?
If the pedal is going to the floor I would say you have a master cylinder problem. If the pedal is spongy the system might have air in it and needs to be bled.
Give us some more back ground and I'm sure someone can post some helpful thoughts .

 

[blackazz]

Brake bandit is a stand alone vacuum pump.and my pedal is rock hard no matter if I use the port off the plenum or use my bandit.now I'm having a hissing sound behind the pedal.no sponge,no air. just a rock hard pedal with no assist.

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[TexasT]

So, again, I'm guessing here, you have a vacuum setup and hard pedal. Did this vacuum setup work before the leed bandit was installed? What master cylinder are you using? Why did you feel the need to install this bandit unit? Do you have a port where you could get engine vacuum with a check valve in line?

Lots to unpack here.

 

[1986 Buick GX1]

BA, just a thought.
If you pull the vac line off the booster and cap/ plug the line going to the vac pump and it runs for a bit and shuts off (operates normally) I’d say you have a bad booster. If the vac pump runs and runs there may be a problem with the vac pump.

Another check would be to pull a vacuum on the booster (hand pump or mouth if your cheap like me). If you can’t hold a vacuum on the booster, the diaphragm is cracked and leaking.

I’d say the hissing sound behind the pedal indicates a leaking booster diaphragm as well.

I like the stand alone vac pump idea, always have vacuum no matter what.

 

[blackazz]

@TexasT my brakes worked if I wasn't in boost but the minute I hit boost my brakes sucked ass!.rock hard pedal under boost.


My brakes felt like the power master when I installed the bandit.my bandit hits 22hg of vac an shuts off,so I know it's not the pump.im thinking the booster just took a crap on me after all this time.


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[blackazz]

First picture is with the bandit holding an shut off.22hg
2nd picture is off the plenum....not good Vac.15hg you need a minimum of 17to work a booster.
When I'm running the bandit my BLM is at 130
Vac Off the plenum my BLM goes to 141
I'd say the booster is junk.

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[pacecarta]

vacuum brake boosters can go bad and leak due to rust or gasoline exposure , hearing a hiss inside car id say replace the booster thats mounted on the firewall
17in/hg of vac should be fine , you dont need a supplemental vac source unless you have less than 12 in/hg of vac
you need to make surethe check that presses into the vac booster holds , if check valve works but the vac leaks down then the booster is bad

 

[KC87]

When I was thinking, that's as far as it got, to converting to vacuum brakes did a crap load of reading and it was amazing how many times a bad brake booster came into play when finished, even brand new ones. Although they may of been calling a rebuilt one as new.

 

[Chuck Leeper]

I'm not sure what a leed brake bandit is.

"(hand pump or mouth if your cheap like me)"
Check your lungs, first....

 

[robert duncan]

Hard pedal with vacuum assist means the booster is likely leaking off the vacuum. That's the hissing sound you hear.

 

[blackazz]

Just an update if anyone cares.but I put in a new booster an everything is back to norm.now I'm able to hold 10lbs of boost an no rock hard pedal after a large boost.say what you will but that brake bandit was worth its weight in gold.Happy boosting peeps[emoji1690]

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[chasmat2316]

Any update on bandit performance. I’m thinking of switching to vacuum brake with a bandit pump

 

[blackazz]

Any update on bandit performance. I’m thinking of switching to vacuum brake with a bandit pump

Love it! Brakes still feel great.

 

[chasmat2316]

Awesome. I will be switching from manual to vacuum with a bandit