how can you tell if your brake booster has gone out?

 

before you turn your engine on, pump your brake till it gets rock hard. then hold your foot gentely on the brake pedel and start the engine up, if the brake pedel sinks then your booster should be fine with holding vacume.

 

ok what is it if you can only push the brake pedel down about a half an inch and you have to stand on it to get that much. Plus i took the top off the brake fluid resivor and stood on the brake and nothing, no bubbles no nothing.....so what else could it be?

 

it does this while the engine is turned on? oh and dont take the cap off the fluid reservoir because the brake fluid is hydroscopic and it would absorb air and it will cause air bubbles in the lines.

 

ah oops i didnt know that, anyways yes it does this with the motor turned on, it seems as if its lost the "Power" part of the power brakes...

 

i would try to bleed the whole system out first. you might have a lot of air in the lines.

 

it made a 'pop' sound when it was on (i was in a bank drive through) i put it in park to sit there then when i pressed the brakes to put it in drive and it popped and the brakes would not go down. no i didnt use excessive force trying to push it down....

 

anybody know anything else besides trying to bleed the brakes?

 

Just bleed the brakes and see where that gets you.

 

Here are some quick tests to determine if your brake booster is still functioning properly:

1. With the engine stopped, depress the brake pedal several times, then depress the pedal hard and hold that pressure for 15 seconds. If the pedal sinks, the master cylinder, brake line or a brake caliper is faulty.

2. Start the engine with the pedal depressed. If the pedal sinks slightly, the vacuum booster is working. If the pedal height does not vary, the booster or check valve is faulty.

3. Depress the brake pedal with the engine running, then stop the engine. If the pedal height does not vary while depressed for 30 seconds, the vacuum booster is ok. If the pedal rises, the booster is faulty.

4. With the engine stopped, depress the brake pedal several times using normal pressure. When the predal is first depressed, it should be low. On consecutive applications, pedal height should gradually rise. If the pedal position does not vary, check the booster check valve.

5. Disconnect the brake booster vacuum hose at the booster. Start the engine and let it idle. There should be vacuum available. If no vacuum is available, the check valve is not working correctly. Replace the check valve and retest.