I have a 1999 4.6 F-150 with 310,000 miles. The engine runs great. However, I've recently started noticing a little sound like a pulley is going out.
This is really easy--take off the fan belts. Start spinning the pulleys by hand and if the pulleys have gone out, you’ll feel the bearing rattling or shaking or it’ll be very hard to turn. It’s very easy to check them when you take the belt off. That’s how I check them when I work on people’s cars. If you want someone to do this for you, a certified technician from YourMechanic can come to your home or office to diagnose your car noise and pinpoint any issues.