Hissing

[Shon350Hodges]

When I take the breather of and start my 5.7 vortex it hisses when starts it idles but hissing why is that

 

[R422b]

That's the sound of pumping losses. (Pumping air through the throttle opening.) I've always considered it normal seems like most sound like that.

Talking about GMT400s using Tapatalk

 

[Nad_Yvalhosert]

Yup. That's what vacuum sounds like.

 

[Schurkey]

Maybe it's mad at you.

Does it snarl when you stamp the gas pedal?