I have an appointment to take my car in for regular maintenance, but I am hearing some strange noises--my car is pretty old. First, there is a knocking noise when I put my car in gear. The noise is coming from the front under the hood. Is this necessarily the transmission, or could it just be something loose? Also, when I decelerate or apply my brakes, I hear a noise like chains dragging the ground. Last, and this only happens at night, I hear a noise that sounds similar to an airplane taking off--no airport around. If I apply my brakes or decelerate, it will stop. Any guesses?