Metallic ticking noise from the MBP
It's certainly inside the MacBook Pro. You should check this out : https://discussions.apple.com/thread/2387469?start=15&amp;tstart=0

This should fix it, helped a lot of people. Click Here

So it happens when you have to apply conductive grease. It's certainly a problem with the CPU I think. After following the steps, your machine shouldn't make any sound.