[shorod]

You need to figure out where the noise is coming from. It could be a self tensioner or idler pulley about to fail, or you may have a water pump with a bad bearing. Without being able to physically listen to the sound, it will be very hard some someone to tell you with any confidence what is causing the noise. Your best bet is probably to find a shop you trust (ask some co-workers or friends for recommendations) and let them diagnose the noise for you.

I see from your other posts that you recently replaced the spark plugs. Did this noise occur immediately after you replaced the spark plugs?

-Rod