Odd sound

[pamp]

After braking I hear an odd sound, a bit of a vacuum wheeze if you will. Done this since I have had the car. Investigating I see a valve in the vacuum line to the booster...."non-return valve" according to the parts picture. Has anyone experienced anything similar?

 

[Luis A.]

If you can hear the vacuum sucking sound inside the car odds are the booster diaphragm is perforated. How much effort is required for braking?

The non-return valve allows air to only go one way such that a vacuum is created within the booster and remains so even as vacuum decreases or goes away in the manifold.

 

[pamp]

Brakes normally. I guess I may be grabbing at straws since I cannot figure out where exactly the sound comes from. Seems to happen though when I ease up on the pedal after a stop. Intermittent as it does not happen every time. This is not a performance issue at all, but a "niggler". I wondered if it might ring any bells to someone else.

 

[deQuincey]

does not ring bells to me
as luis said, the nonreturn valve is only blocking the air way back into the manifold when you brake
if you experience a noise coming from the brake action you should experience a loss of pressure, thus a poor braking performance and a lot of effort to brake
if that is not the case, i am lost !
...wait a minute, you said "after braking", so it happens when you release the brake ?
it is odd, but when you brake you compress the brake booster membrane helped by the engine suction, and the rear side of the brake booster is letting air coming in to allow this front compression,
so when you release the pedal, the air that is placed in the rear side of the mambrane is forced out by the spring of the booster, that air has to exit the brake booster rear side by some vents strategically located, there is an air filter too, could it be broken ?

check this by openeing the hood, and with engine running ask a friend to brake and release while you carefully inspect the area

hope this helps

regards