Brake issue: They don't work when engine is running, but fine when engine is off...

AluH20 · May 21, 2004

Today on the drive home from work I noticed my brake pedal can be pushed to the floor completely with very little resistance. The pedal comes back up fine, it just feels like - well the brakes aren't working!

When the car is shut off and the brake pedal pumped, it pressurizes fine. What would cause the brakes to fail when the engine is running, but build pressure normally when the engine is off???

2FastTSiAWD · May 21, 2004

Well, I dont have a definite answer for you, but the brake booster is run of of vaccum, so maybe you should do a leak test and go from there?

AluH20 · May 21, 2004

Hmmm interesting. Do you think there is a leak or crack in that hose from the intake manifold to the master cylinder?

Hanzuki · May 21, 2004

to test the boost, pump the pedal (engine off) untill it gets hard, then hold it, if it slowly sinks to the floor, the boost is facked. I would also check the condition of your pads and rotors, as well as all your flex hoses, and brake lines. also check and make sure there is enough fluid in the resivoir. if all is well, and the booster passes the test, try bleeding the system.

AluH20 · May 21, 2004

Update:

I checked the reservoir and it was empty! Hmmmm, my brake light is also on and after searching I think this might be a brake pad issue. Think so?

2FastTSiAWD · May 21, 2004

The pads would not cause the resivoir(sp) to go empty, I would start by checking all the wheelwells, look for brakefluid. If a caliper is leaking, you ll know. If not, then start checking all of the lines, just get under the car and look for big wet spots on the underbody. Good luck.

AluH20 · May 24, 2004

Found the problem

It's my brake booster. There was fluid leaking all over those cylinder shaped things and around those 4 bolts- it was so bad the fluid is dripping down my tranny bellhousing. Unbelieveable!

I checked the part on CAPS and i'm going to call and get a price on it tomorrow.

Chypriss · May 26, 2004

good luck with the brake booster, its probably going to cost a pretty penny. I worked at Uhaul for a bit and my brake guys hated changing the brake booster, its a pain in the ass. GOOD LUCK

AluH20 · May 26, 2004

$1700 new. I'm going to look for a trashed out parts car- until then I'll just carry around 4 bottles of brake fluid in the back seat

NOMIEZVR4 · Jul 8, 2004

to test the boost, pump the pedal (engine off) untill it gets hard, then hold it, if it slowly sinks to the floor, the boost is facked. I would also check the condition of your pads and rotors, as well as all your flex hoses, and brake lines. also check and make sure there is enough fluid in the resivoir. if all is well, and the booster passes the test, try bleeding the system

alrite i tried this on my car(its a bonneville) what hapens is that the brake pedal doesnt slowly go down. if i push on it it does go down but takes a bit of force..i dont know if it is my brake booster or not. its when i drive sometime si have good pressure and soemtimes the pedal just goes all the way down and takes a while to stop(like a soft pedal). i have new pads and rotors so i kno wit cant be that. i thought it was the master cylinder but than gain i have pressure sometimes so i dont know
any help?????
thanks

Brake issue: They don't work when engine is running, but fine when engine is off...

AluH20

2FastTSiAWD

AluH20

Hanzuki

AluH20

2FastTSiAWD

AluH20

Chypriss

AluH20

NOMIEZVR4

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