Noise from engine help.

Hi all i have S reg Disco and it is making a metalic noise, it appears to be comming from around the water pump, altanator area. I am drawn to the water pump because my experiances with alternators tells me they normmaly fail, they dont make a noise first. The engine is running at normal temp so i think the pump is work but susspect it may be on the way out.

Any other ideas??

coul be bearings in the water pump drive belt tensioner, if you take the belt off you can spin any of the wheels that carry the elt and find the noisy/rough one

or spray WD 40 at bearings when engine is running then if the noise stops thats the one.