trucks running fine this morning. go out today for lunch start the truck and there is a loud vacuum leak(sounds like one anyways) under the dash near the brake pedal. when i push the brakes in it stops, or when i turn the steering wheel it stops. other than that i hisses the whole time. popped he hood with the engine running and you could hear it around the brake master cylinder. anybody got any ideas? it that where the vacuum pump is located? I drove it to lunch anyway and it ran fine, but never stopped hissing unless I was slowing down or turning. suggestions would be appreciated.

thanks, tom

 

Brakes don't use vacuum I would look to fluid level in the power steering/hydro boost reservoir.