If you do not know when the timing belt was done last, then by that noise you can hear. It's a good bet a pulley or tensioner is now borderline broken, as that noise is a tell tale sign it is failing already
"It seems like a lot of bolts have been omitted... Judging by the amount of them in the 'random fasteners' bag. I am beginning to think my Z is being held together by zap straps"