Hey guys -
I have a 2005 A4 1.8T Quattro and yesterday when i got home i got out of my car and heard a hissing noise coming from under the hood. I heard it from the top left so i popped the hood to take a look. The noise was definitely not loud but if you listened for it you could hear it. It was pretty faint and i didn't see any steam or smoke. I thought immediately it would be a hose or something but didn't see anything out fo the ordinary. I heard the noise today to after driving a very short distance. I apologize if this is a dumb post, just making sure nothing is wrong.

 

your turbo spooling perhaps....

 

Why/How would the turbo spool when the engine is off, the throttle is closed, and the driver is outside the car looking under the hood?

Same thing happens with my car; after driving it, there's a hissing noise coming from the engine compartment. I don't think it's anything to worry about, maybe the car is bleeding off pressurized air in the intake system, or maybe it's forewarning of the impending car apocalypse . Can someone confirm/deny/make fun of my knowledge?

 

i believe thats the air conditioner. even if u have ur car set to room temp ur ac will be working. try not using any air at all just turn off ur heater/air conditioner and there wont be a hissing. i and everyone i know with an audi does the same thing. its nothing to worry about.

 

Like Sandman said, it is most likely the a/c, i know my a/c system hisses anyway, chances are your safe.

 

Correct.. its the A/C! I didn't use A/C today and did not hear a hissing noise. Also, the hose and compartment where i heard the hissing noise had a bit of moisture on it and was cold. Thanks alot guys.

 

its pretty sweet, when i start my car up in the morning, it sounds like a bong from inside the vents!!!

BONGGGGGGGGGGAAAAA!!!!!!

 

im sorry i misread the part about the car being turned off...