Here's a tip that I used years ago when I was still working on cars for a living to try to isolate noises: Find a long screwdriver, the thin the better. I use a tune up screw driver which is designed to get to the mixtures screws on carburetors. Put the metal tip on part of the engine (BE VERY CAREFUL AROUND MOVING PARTS LIKE BELTS!!!) and put your ear up to the handle part. Move the screw driver around to different parts of the engine until you hear the noise the loudest and most times you will be in the area the cause of the noise is in. In this case if it is a bearing you will probably hear the noise the loudest from the bottom of the engine, maybe try "listening" to the block where it meets the oil pan. A lifter would be loudest on the head. I'm not familiar with the V6 water pump location but if it is easy to get at you can use this to check it out too. I've isolated bad alternator bearings the same way.
If you want play with this just as a test fuel injectors are a good place to start.
This is like the poor man's alternative to a stethoscope.
Hope this helps!
