Hi,
I have a 2000 Volvo S40. Recently, when car is in motion, I can hear a hissing sound from outside (near passenger side). This sound goes away when vehicle comes to a stop. The sound is present at all speeds (city, highway). I can hear this sound only when windows are down.

Any ideas what this could be? How can I troubleshoot the problem?

Thanks!

 

Does the hissing happen while you are at idle?

 

There is no hissing sound while idle...

Thanks!

 

Is this a turbo car?

 

Yes, this is a turbo.

Thanks..

 

Could be the oil trap box. My car was making a loud whining noise behind the intake manifold. You can check by starting the engine and let it run a short time. Then try and take off your oil cap. If it seems stuck it is your oil trap that is getting clogged. The sound is from the oil trap box struggling to get air.

 

check the steering column lower boot if it is pop off

 

Is this a riddle?

 

Well the intake is on the driver side.

Every-time i see these threads i hope they are people realizing that the turbo whistles/whines, and it has only happened once.. But was hilarious

 

By any chance did you park the car in a field with the doors open in west Texas?