Feel around under the water pump. THere's a small cover held on by two 10mm bolts. Remove the cover and loosen the tall head 10mm bolt underneath. Push the small metal tang towards the center of the engine until the slack is taken up, and retighten the tall head bolt and seal and replace the cover and crank it. SOunds like BS chain loose to me, and that should tighten it up so the noise is reduced. TIme to start thinking about a complete timing kit.

Not responsible for advice not taken...