Hissing Sound when turning on engine

[Spaceman]

Hi All,

I encounter this hissing sound occassionally when I start my engine. It seems to come from the radio unit but it is still there when I turn it off. It is definitely coming from the front area. It lasts for about 8 sec or so. I will get this sound when the engine is cool, especially in the morning. Mine is a 318i. I hope somebody could help me on this. Thanks!

 

[piggyboyz]

Re: Hissing Sound when turning on engine

It could be due to the air con gas moving in the air con system when u start up. The noise could be louder especially when there is insufficient gas in the system.

Get it checked.