Thanks! I just removed the OD. Guess ill have to invest in a new one ;(Yes, that is the optical disk drive (ODD) checking for inserted media, it is a normal sound for older Mac models, and as you say, your ODD is broken, the repetitive sound it makes is probably normal. You could remove the ODD if you want.
An external will hopefully suffice? They only cost around 30 , a used or new S-ATA ODD compatible with your MBP might cost much more than that. And you can use any of the Optibay adapters out there to add a second HDD or an SSD.Thanks! I just removed the OD. Guess ill have to invest in a new one ;(