Do you remember the screams of protest when serpentine belts were dumped on us by the automobile industry? One broken belt and everything's dead? They are an absolute nightmare to replace? They cost a fortune? Now we wonder why they weren't invented sooner. The old "fan" belts were a pain
to replace and tension. Slippage from being too loose was annoyingly common and any one of them would leave you just as stranded when broken.
First of all, do you have a serpentine belt and does it need replacing? A serpentine belt is much wider than the conventional "v" belts and it will have a number of ribs on the inside edge. It will have the distinction of being the only belt under the hood. Don't be alarmed if it has a few cracks on the inside edge. Once these cracks occur in 1/8 inch intervals, it's time for a "pre-emptive transplant".
If your vehicle uses a serpentine belt with five ribs, don't settle for a four rib replacement (even though it will fit and work). Some cheaper brands will consolidate several lengths to reduce inventory and part numbers. It may be wise to pay for a name brand or dealer replacement for the simple reason of getting a better fit.
The single most important step to replace a serpentine belt is to ensure you know the path of the belt BEFORE you remove it. It looks easy to remember but trust me, when the belt is off, it's easy for uncertainty to creep in. The vehicle will have a diagram under the hood. Make sure it's not missing. Make a sketch of the path either in a notebook or in chalk on the shop floor. Better yet, take a couple photos with your digital camera.
Gone are the days of searching for which of those grease encased bolts loosens the belt, prying until your eyes bulge to apply tension and simultaneously re-tighten the bolts. And then do it all over again after determining the belt is now either too loose or tight. These fond memories
can now be left to restoration and vintage car projects. All serpentine belt equipped vehicles will have a tensioner wheel. Whether it's a bolt, hex, or torx fastener, applying quite a bit of force (often 80 pounds or more) in a counter clockwise direction is standard. Just slip the belt off the handiest pulley and release the tensioner.
Before installing the new belt you should check the condition and alignment of the pulleys. They may be out of alignment diagonally (crooked) or parallel to each other. Either situation may have caused premature wear of your belt and will have to be remedied. In some cases, washers can be used as shims, but replacement of the component is often required. Carefully check each pulley for nicks or sharp edges. The tensioner wheel itself is a common source of failure. Make sure that it works and that it spins freely and quietly. There will be at least one idler wheel, which should also spin without noise or sideways movement. The idler wheel is normally smooth and will allow the belt to slip off if it's in poor condition. The bearings on these devices endure a punishing life and will wear out. So do the bearings on the alternator, air conditioning compressor and water pump. Grease and oil are a death sentence to any belt. If it exists anywhere on the serpentine belt path is must be cleaned. Just as importantly, the source must be isolated and fixed.
To install the new belt, start at the lowest pulley and work upwards toward the tensioner wheel. Be extremely careful to avoid dragging the new belt through grease and dirt. Make certain the ribs on the belt align perfectly to the grooves on each pulley. A mistake here will doom your new belt to a premature death. Finally, pull back on the tensioner and slip the belt on. Strictly avoid releasing the tensioner with fingers between the belt and a pulley. Most tension wheels will have indicator marks. Make sure the new belt is within the min and max. ranges. One last thing to check: the new belt will fit tighter and will follow a slightly different path than the old one. Ensure the belt has a clear route to follow. Once in awhile a loose bolt or bent piece of tin will interfere.
Before throwing the old belt out, strongly consider keeping it in your emergency toolbox (assuming you've replaced the belt before it exploded into shreds). A spare belt might really save your day in the future. Or, you can sell it for a small fortune to a less prepared motorist in the middle of nowhere. Just kidding of course.