Do you know what would cause the steering column in my 2001 Chevy truck to make a growling or rubbing noise when I'm turning the steering wheel to the left? It only makes the noise while I'm turning the wheel (I've heard power steering pumps growl and it doesn't sound like that and they seemed to growl even while you held the wheel still) and this noise seems to get louder the farther I turn it. Any ideas?

check the power steering fluid level. It may be low.