brake vacum leak

[RAUL AGUILAR]

This morning when I went to turn on my ST I noticed a odd air sound. :angry: It was coming from the direction of my brake pedal. Every thing works fine but when i let go of the brakes or i rev the engine i hear either an air vacum or air blowing. If i press on the brakes again it goes away but comes right back after i let go. Is this normal or is my Boster going out?

thanks in advance for any leads.

 

[Dingo]

Probably the bladder in the booster. On a dead street, go about 10 mph... Put the truck in neutral, then turn it off. See if it stops as easy as when the engine is running.