Why did automakers go from V-belts to a serpentine belt? The serpentine belt has a few advantages over multiple V-belts. A single belt to drive all accessories means better space efficiency underhood since there's no need for the alternator, AC compressor, water pump, and other accessories to be offset from each other. The serpentine belt also means less parasitic drag on the engine.
How can I tell when a belt is wearing out?
Your serpentine belt or V-belts will start to look frayed at the edges, cracked, or glazed when they're starting to wear out. These tough belts are fabric-reinforced and can last 60K miles or so, but it's still a good idea to check their condition regularly. Newer vehicles use belts made of EPDM and this material doesn't crack or fray as easily, but wear will occur in the ribs. To check this type of belt, there is a tool that is used in the ribs to determine if a belt replacement is necessary. The tool has notches that fit into the ribs of the belt to determine if there has been material loss that would cause noise, belt slip and a potential failure.
How hard is it to replace the serpentine belt?
Serpentine belts are a little tricky, but most vehicles feature a routing schematic under hood that shows the proper path the belt should take. The belt is designed to work with a tensioner, which is like a spring-loaded idler pulley that goes against the belt's back side. There's no lubrication point on the tensioner, and it can seize up and fail over the years. When replacing the belt, it might be a good idea to replace the tensioner as well. It can be difficult to get the right kind of leverage on the spring-loaded tensioner to move it out of the way when replacing the belt. You can tools borrow a loaner tool kit from your local store that will have a flat bar that can fit into tight clearances, with a special fitting for the tensioner.
To install a V-belt, you'll need a large screwdriver or pry bar to put leverage on the alternator in order to bring the belt to the right tension. You can then tighten the bolt for the alternator in its sliding bracket (some alternators feature an adjustment bolt to make this job easier). The belt should have no more than about ½ of deflection in either direction.