Hissing sound from air filter after motor is shut off??

[DemonGT]

iv heard that if you arnt venting the crankcase good enough pressure builds and when you shut the car off you can hear a hissing sound from air coming out the air filter...i do hear a hissing noise when i shut the motor off...i have a stock style PCV in the pass valve cover and a breather cap on the other cover that has a vac. nipple that i have hooked up to the intake also....

am i missing something hear? is the breather cap messing with the PCV so its not working right?....just seems like the way i have it set up it would be more then enough to vent the crank case and not have pressure build up

 

[cola8d8]

Do you still have a smog pump? My friends was doing the same "hissing" after shut down and his problem was the smog pump.

 

[Daggar]

You can get a hissing sound from the airconditioner compressor as well. This time of year (since you're probably not running air) it's not as common unless you're using the defroster.

 

[DMAN302]

Don't know but mine does it as well, I just ignore it...don't worry about it.

 

[HISSIN50]

might check to see if it is the charcoal cannister and its plumbing. it is below the air filter.

good luck.

 

[BlackFox5.0]

It normally does not last long, but after oyu shut your engine off, there is still vacuum in the clyinders, and the way for it to become presurized back to atmosphereic pressure is to suck air in from the throttle body.

I take it that you plugged the nipple on the throttle body?

That sound is most likely just air still getting sucked in to the engine through the filter.

 

[89rdgt]

excatly what the last guy said. If you have a free flowing intake kit it will amplify the sound.

 

[DemonGT]

yea...i must be air going INTO the filter...i have no A/C and have no smog pump..and my T/B has no nipple..so that must be it...