i've had my 91 sentra se-r for an year. recently when i start the car and start driving it i hear a noise that sounds like it's revolving or rubbing in the front of the car. it doesn't make the noise when the car is at an idle or when the car is revved. only when the car is moving the noise start to go and the faster i go the faster it revolves. it usually happens when the weather is cold and the car just started. i was wondering what the problem would be?