Nissan Repair Questions? Ask a Mechanic for Answers ASAP
Hello I will help you with your question,
Is oil or coolant getting on the belt? Did you clean the pulleys before the belt was installed?
There is a TSB about noise and points out that it may be the alternator making the noise. If you spray a little water or glass cleaner on the belt while it is making noise and the noise stops then it is the belt or the belt tension. If the noise persists then it is a pulley or the alternator
Click here for tsb
Try that and let me know what you find.