diagnosing brake booster

swisherred

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I am trying to determine if I really did kill my booster or not and Id like someone that really knows and understands these systems to chime in if possible.

1967 Newport...possibly Bendix? single diaphragm power drum.

I still have brake assist.
I do not have a constant hissing inside the car.
I do have a momentary hiss inside the car when I depress the pedal...only for the first 1/2" or so of travel, then it goes away.
I can force the hiss to stay constant if I keep the pedal within that initial region of travel.

I'm not sure what else to point out.
I'm wondering if I have a seal that is failing, or the control valve is failing? or if its actually working as it should and the noise I'm hearing is just the initial pressure difference when the valve opens and I'm just needing an adjustment somewhere. I do not believe it to be the original booster, but a replacement.
 
also...if it is bad, is there a newer model that is easier to find that will still work? Its not original, and im ok with that.
 
I am trying to determine if I really did kill my booster or not and Id like someone that really knows and understands these systems to chime in if possible.

1967 Newport...possibly Bendix? single diaphragm power drum.

I still have brake assist.
I do not have a constant hissing inside the car.
I do have a momentary hiss inside the car when I depress the pedal...only for the first 1/2" or so of travel, then it goes away.
I can force the hiss to stay constant if I keep the pedal within that initial region of travel.

I'm not sure what else to point out.
I'm wondering if I have a seal that is failing, or the control valve is failing? or if its actually working as it should and the noise I'm hearing is just the initial pressure difference when the valve opens and I'm just needing an adjustment somewhere. I do not believe it to be the original booster, but a replacement.

If it is not hissing all the time, it probably does not have a bad diaphragm inside the booster. A small amount of noise is normal as the booster starts to engage. There is a rubber bellows on the actuator rod on the back of the booster where the linkage comes out of the booster, if that bellows is bad, it will make the hiss louder than it would otherwise be. A quick check for a booster leak is to turn off the engine and let the car set for 10 seconds. If there is still enough vacuum to operate the booster, it is likely not leaking.

Dave
 
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