By cam bearings i'm assuming you mean the two roller bearings directly behind the cam pulleys? Not heard of anyone having probs with these? I'd imaging they'd have to be pretty knackered to make any significant noise. Anyone else had probs with them?

Apart from that i'd check also the tension of the 2 alternator belts and PAS belt, make sure not overtight. Cambelt tension as a rough, rough guide can be checked by gently turning belt along its longest edge - should just turn about 90degs, any less then maybe too tight.

You can use a long screwdriver to "listen" to each surrounding compenent with engine running - to help pinpoint any poss bearing failure in water pump, alternator etc.. - BUT, only do this if you're confident - if you drop that 'driver onto the cambelt or any other rotating parts you'll be worse off!

BE WARNED - good luck!