@johhntran and marshun,
Thanks for the info. I will take a look at those. By the way, I am no way near even a newbie mechanic so I don't know the terms you use or where the parts you mentioned is located.
However, I am trying to learn to DIY my car to save the bucks!!!
After driving the car today under hot weather, I have a feeling that the problem could be from the rack and pinion because the noise got much louder whenever the wheels are turned just a little bit.
But I will check and let you guys know more.