smokinx2

hi i have a 1998 nissan frontier my battery kept going dead and instead of buying a new alternator i changed my belts they were stretched and my alternator belt was dry rotted.well all i did was change the belts i didnt mess with anything else it ran and sounded fine before i changed them but after i changed them as soon as i started it up there was this real loud rattle sounds like its coming from the top of the motor.has anyone ever heard of a vehicle doing that after you change a belt or does anyone know what it could be.maybe changing the loose belts to new belts did something i dont know please help me.thank you