when i turn my engine off i hear a quicking hising noise

[SpenderE46]

help help,,,,

when i turn my enginee off i hear a quick hising noise,

any one know what this could be

any ideas would be great

[Hootie]

no sweat, mine does it too. sounds like it comes from the center dash? i think it's just the vents pushing the last bit of air out.

[SpenderE46]

but mine come from the enginee bay, i lifed up the bonnet and got my mate to turn the engine off and when he did it then a hisssss came out, any thing wrong , any thing need changing like a fliter or any thing

[jakksfor20]

It may be coming from the intake. You tend to hear it more from aftermarket intakes, but it may be possible from the OEM one. I've never heard it on the Bimmer, but I'm used to hearing it on my other car and don't mind it.

[Dirty_Tool]

Bad check valve for the brake booster?

[SpenderE46]

well if it was the brake booster, then my brakes would not feel correct, but they are fine and my car stop very nicely, could this be any thing else,

the more options it could be the better ????

thank you

[Hootie]

"but mine come from the enginee bay, i lifed up the bonnet and got my mate to turn the engine off and when he did it then a hisssss came out"

I'm pretty sure some of the blower components are IN the engine bay, just under the cabin air filter. Try to pinpoint where the hiss comes from. If it sounds like it's coming from someplace near the center of the car, towards the firewall, it's probably just your vents. If it's towards the front, check the air intake.

[SpenderE46]

if it come from the vents near the firewall is this normal,,,,,,

f this come from the air intake is this normal,,,,,

[SpenderE46]

one other thing it sounds like a dump valve on a turbo car, not a loud, but i am sure u can get my point

[Hootie]

"if it come from the vents near the firewall is this normal,,,,,,"

Well, it happens in my car on a routine basis (not always, but not alarming when it does). It only happens when I turn the car off and I hear a "hiss" from the vents. Since I have not recently installed a Diamondback Rattlesnake in my heating coil, it must be the last bit of air being flushed through the vents.

[Ocean02]

I hear an electronic noise when I shut off my car (sounds like maybe the antena retracting on my other car) only there's no external antena. Idea ideas on this one?

[BMWJNKY]

The noise is normal. It is just compression bleading back into the intake from a cylinder where the valve didn't close all the way before the engine was shut off. There is nothing to worry about because 99% of the cars on the road do it, and like someone else said the noise is louder with aftermarket intakes because the stock noise baffles are not there anymore.

[versace]

I had the same problem on my e46.When I stop the car I was hearing a terrible noise coming from the engine,for a few seconds and then stopped.
I heard that noise also when I drove off on first gear.After checking in the service they told me that the problem is in broken or torn hose.
Here is a link about my problem:
http://www.realoem.com/bmw/showparts...11&fg=15&hl=10

[EXtech]

beyond the potential broken broken hose.. the crankcase vent valve (part #1 in your link versace). These things are notorious for making funny noises including the hissing sound you hear. The hissing sound is coming from pressure built up inside the crankcase. Have the vent valve replaced and your noise should go away. The other thing you might want to check is your air filter. Make sure the air box is sealed properly and that the air filter is seated properly. Any sound of pressure bleeding off from the engine will be amplified if the air filter isn't seated or the box isn't completely closed. Ironically, I think there is a thread about this just recently.