My car recently has been making a loud whining/screeching noise when I start it up. The previous owner gave me a V-belt (nissan part 11950-31u00) adn I was wondering if I replace it would it fix my problem?

 

http://www.greghome.com/Greg's%20Garage/1999%20Nissan%20Maxima%20SE/DriveBelts.htm

 

Yes it will and it is very easy. Purchase you some belt dressing also. I going on the fact of "V" meaning serpetine belt. If so, get a long cresent wrench, a 12-14mm socket (not sure of size), a 12 in. extension for the socket should work and a paint pen.
Take the crescent wrench and loosen the bolt on your tensioner pulley just enough so when you loosen your adjuster it will move up and down freely. Before you loosen the adjuster mark the side of the bolt where the adjuster comes through a flat base. Now loosen your adjuster. Have a buddy help you here. Have your friend pull the adjuster up while you slide the belt off. That was the easy part. The no so hard part is putting on the belt. Remember how you took it off is how you put it on. Place it around your crankshaft pulley and the pulley towards the back. Then while your friend continues to hold he adjuster up you snake your hand down and loop it around the front pulley. Friend lets go you tighten the adjuster to your mark and tighten the pulley. Spray the inside of the belt with dressing. Crank and listen for squeeling at startup and running. If either happens your belt is either to tight or to loose. I prefer to start intentionally loose and tighten until whine or squeel goes away.
I know this was a novel. But I changed my v-belt, at work, on the clock and in less than 30minutes. good luck

 

If you cant reach the idler pulley bolt from the top, remove the right wheel, remove the inner fender splash guard, and the crankshaft and idler pulley will be right in front of you. Removing the inner fender splash guard sounds complicated, but it is not. It is made of plastic, and there are only 4 screws to remove. You have much better access to re-install the new belt this way also. Jusy make sure you have good jacks to support the car. Dont work under there while the wheel is removed and the vehicule supported by the flat tire change jack delivered with the car. Time : 30 minutes as well.