Help with a rubbing noise on a 2005 Pickup!
 

I just bought a 2005 Chevrolet Crew Cab Z71 with 80200.oo miles on the clock and every time I turn the steering wheel to the left or right I get this rubbing sound as if metal is rubbing on rubber. Looking under the hood I noticed the steering rod comes out the firewall through a rubber tube. If you have experienced this noise and know what it is and the fix for it I would like to hear your response! Thanks for helping a Newbie here, out!