[katsudon]

I started hearing this weird clicking noise about a month ago. It's pretty loud that I can hear it even while sitting in the car. I have a 2008 328i and have about 120k on it. It gets louder when I turn on the air con.

Does anyone know what might be causing this and if it's an urgent matter?

[u2b]https://www.youtube.com/watch?v=4agG5K_upX4&feature=youtu.be[/u2b]

Thanks in advance!

[patents]

Well, that definitely isn't normal. If I had to speculate I'd say your belt may be fraying and you are hearing it slap against the pulleys. But I'm pretty sure it's going to be belt related somehow (belt, tensioner, pulleys, etc.) since engaging a/c changes the sound.

If it is belt related, I would consider it urgent until you figure out exactly what's going on. The belt could break at any moment. You won't be stranded, but you'd need to go straight to the shop. There's also an issue of broken belts getting sucked into the engine, but that may only be an issue with the N54. If that happens your engine is likely toast.

[Three_thirty_I]

My bet would also be something belt or tensioner related. Sounds like a shot bearing on a tensioner more than anything else. I would attend to this as soon as you can! These engines don't take too kindly to snapping serpentine belts!!