97 Grand Am Brakes

Hello, everyone. I hope someone has a suggestion for this... I have a 97 grand am get, 165,000 miles. The brake pads have been replaced but the brakes feel strange. This is a 2.4, auto, power brakes. Right now it feels like the standard brakes, not power brakes. This is an ABS car. I checked the vacuum line running to the brake v-booster, no cracks, etc. I pulled the line off, started the engine, placed thumb over the hose. That killed the motor. I started it again, (was running at high idle due to hose being off), replaced the hose onto the v-booster and the idle settled back down. I was hoping this would tell me whether the booster was bad or not. The brakes work, but you have to stand on them. Nothing like they use to be. Anyone have any thoughts on it?

Thanks!

Boss1b

Hello, everyone. I hope someone has a suggestion for this... I have a 97 grand am get, 165,000 miles. The brake pads have been replaced but the brakes feel strange. This is a 2.4, auto, power brakes. Right now it feels like the standard brakes, not power brakes. This is an ABS car. I checked the vacuum line running to the brake v-booster, no cracks, etc. I pulled the line off, started the engine, placed thumb over the hose. That killed the motor. I started it again, (was running at high idle due to hose being off), replaced the hose onto the v-booster and the idle settled back down. I was hoping this would tell me whether the booster was bad or not. The brakes work, but you have to stand on them. Nothing like they use to be. Anyone have any thoughts on it?

Thanks!

Boss1b

When you disconnected the vacuum hose to the brake booster, did you disconnect the vacuum hose at the brake booster connection? OR Did you disconnect it at the engine side of that vacuum hose?

If you have disconnected the vacuum hose at the brake booster and put your thumb on the end of that disconnected vacuum hose then the engine should have idled because it is not introducing extra air in the intake system.

Anyway, the vacuum hose attached to the brake booster allows the engine to pull a vacuum on the brake booster and that makes pressing the brake pedal very easy when then the engine is running. If the engine is not running which means that it is not pulling vacuum at the brake booster and that makes the brake pedal hard to push after 3 presses of the brake pedal since there is no vacuum assisting the brake booster.

The problem is probably a small leak in the brake booster itself and not allowing the engine (engine running) to pull total vacuum on the brake booster and causes you to press harder on the brake pedal.

Another possibility is that there might be some binding in the brake pads itself.

Another thing, has your brake fluid ever been flushed?

Brake fluid does were out so to speak, it also gets moister in it over the years and that'll make them not work properly.

I would buy a large container of DOT GM aproved brake fluid, and start flushing the system by bleeding them many, many times.
If you hav a vacum tool that will help pull that nasty stuff out.
Brake fluid is pretty much clear, if you check the fluid in your fluid resivour I bet its black in the bottm :grinyes:

btw-If you had a vacum leak or your B. booster was bad,
the pedal would be stiff as when the car is not running, becasue their is not boost to assist.

Thanks for the advice Slade and zeroinfinity... I did remove the vacuum hose from the booster end and plugged it w/my thumb. It killed the engine twice. probably another problem!

My daughter currently has the car as school, (college) so will be a few days before I can get my hands on it. I am planning on changing the pads and checking the rear shoes, so will change the fluid at that time as well. will also make sure nothing is binding on the pads. The pedal is hard to press when motor is running, though not quite as hard as when the motor is not running. Idea of small leak in booster makes sense. Is there a way to test the booster or is it just easier to replace it?

Thanks,

Not a big deal to change out, but they are pricy !

To check the booster depress the pedal and start the engine.
If the pedal goes down a little its operations normal.

Depress the brake pedal several times with the engine running, and make sure thier is no change in pedal distance.

To check for air tightness, run the engine for a few minutes.
Depress the pedal several times slowly, if the pedal goes down farther the first time but gradually rises after the second or third pump the booster is air tight.

Deoress the pedal while the engine is running. Then stop the engine with your foot on the brake. If thier is no change in pedal travel after 30sec the booster is air tight.

Hope that helps !

Xeroinfinity,
thanks! I'll check it out. I had been afraid it was something with the ABS system, which I assuem would be quite costly. Hope this identifies the problem!

Thanks again.
Boss1b