Is my power brake booster bad? [Archive] - Chevy Nova Forum

: Is my power brake booster bad?


NovaShop.net
18th-August-2007, 12:53 PM
I have power drum brakes, I have adjusted my brakes and bled them several times after replacing a wheel cylinder. I still can not get a hard peddle. Before one tire was hanging up, due to a leaky wheel cylinder. I broke down and bought a power bleder, and bled them again. After I drove the car, I noticed that the brakes work OK if you hit the brakes hard, but if you press on the brakes slow it goes all the way to the floor with very little braking power. When the Nova is not running I hear an air whoosing sound when the brakes peddle is pushed in, this does not seem normal to me.

Any advice? Thanks

Pauls72
18th-August-2007, 01:00 PM
Pedal going to the floor sounds more like a bad master cylinder. If you hit the pedal hard and hold it does the pedal fade away?

To check out the booster try kinking the vacuum line and see if the air sound goes away and the engine rpm changes. Or unhook the vacuum line and plug it.

BPeer1
19th-August-2007, 01:27 AM
If your brakes were OK before, I don't think changing a wheel cylinder would make the power booster or the master cylinder go bad. Keep bleeding?
BP

NovaShop.net
20th-August-2007, 02:05 AM
The car has not been driven for at least ten years, so I don;t know the condition of the brakes before.

Paul, The pedal does not bled down when you hit it hard, it seems to hold nicely, but it goes clear to the floor when you lightly press the pedal. Would that be the master cylinder?

I'll check the booster vacuum tomorrow, I do notice that the engine speed lowers when the brakes are pressed.

David&Melissa_h
20th-August-2007, 02:46 AM
I have power drum brakes, I have adjusted my brakes and bled them several times after replacing a wheel cylinder. I still can not get a hard peddle. Before one tire was hanging up, due to a leaky wheel cylinder. I broke down and bought a power bleder, and bled them again. After I drove the car, I noticed that the brakes work OK if you hit the brakes hard, but if you press on the brakes slow it goes all the way to the floor with very little braking power. When the Nova is not running I hear an air whoosing sound when the brakes peddle is pushed in, this does not seem normal to me.

Any advice? Thanks
That whooshing sound is normal it is the air in you booster you should notice that if you pump it with motor off the peddle will get hard when the air sound stops.
Doesn’t sound like you have a booster problem, the booster only aids in the force to press the peddle not the travel.
When you press the brakes slow and it goes all the way to the floor with very little braking power does it get better after you pump it a couple times?
If so you have air in the lines rebleed..
If you change your master I would drain and flush out all brake lines and refill with fresh new fluid, or better yet if it is all original I would for safeties sake replace all rubber lines and wheel cylinders with a new master you don’t want to mess around with the brakes....

the FLYER
20th-August-2007, 02:56 AM
if you think the master is bad you can unbolt it from the booster unit and check for moisture coming from the rear of the master leaking into the booster unit. most of the time you can do this without disconnecting the lines.

IF the master has leaked into the booster unit you'll find that even if ya replace the master cylinder that later on, no telling when, the booster WILL go bad due to the fluid deteriorating the booster's diaphram.

so, if the master has leaked into the booster replace the complete power brake booster assembly.

after sitting for 10 years, my honest opinion would be to replace or rebuild the complete hydraulic system... including all 5 brake hoses.

64PRONOVA
20th-August-2007, 10:23 AM
A bad booster won't make the pedal go to the floor. It will just get harder to push the pedal. Unless you have brake fluid leaking from a wheel cylinder or a line, it's probably the master cylinder as Pauls72 mentioned.