Mechanical noise in steering

Whenever I turn sharply, I hear a mechanical noise in the steering when it is turned to the far left or right. Any ideas on what it could be? My understanding is that my truck doesn't have a dedicated power steering fluid container. So I don't know what else to check.
It is a 2006 Tacoma 4 door TRD 4x4. Thanks for any help.

 

check your power steering fluid first

 

Is it at full lock left or right? If so, there are bump stops that prevent the wheels from turning any further. When they are in contact with each other they will make a noise if the truck is moving.

 

Alright, finally got a chance to check today. Power steering fluid looks to be at the proper level, but very dirty. I'll try to change it to see if that helps.
The mechanical noise doesn't happen every time and, when it does, it is happening when I'm driving slowly and turning the wheels sharply, like when backing out of a tight parking spot. I wouldn't say that it's happening only when I I get to the extreme left or right, rather, as I get close to extreme left or right. Could this be the pump going out?

 

Mines done this a handful of times too. Haven't figured out what it is...happens when backing up and turning the wheels (not to full lock). I would check your tire pressure, mine started making a noise constantly when backing into my garage, turned out my tires were low and deforming to the asphalt and causing a noise. Not the crunch noise of before, but still might be what you are hearing.