You know that long belt that snakes around the front of your engine? It’s called the serpentine belt. The belt’s driven by the engine as it turns. It powers your alternator, air conditioning compressor, and power steering pump. On some vehicles it also runs the water pump, radiator fan, and power brakes. Sounds like a lot of important stuff doesn’t it? If your serpentine belt were to break, your battery would die in a few miles. If it runs your fan or water pump, your engine could overheat. And steering and braking could be more difficult. Obviously, the best thing is to replace your serpentine belt before it breaks. Check your owner’s manual for when it’s recommended to replace your serpentine belt – or just ask your service advisor. He can inspect the belt as well to see if it’s in trouble. You may have been told to look for cracks in your belt to see if it needs to be replaced. Of course, cracks are still a concern, but modern belt material doesn’t crack as often as old belts did. What we look for these days is the thickness of the belt. We have a special little tool that measures the depth of the grooves in the belt to see if it needs replacing. A worn belt can slip or be misaligned, putting undue stress on the accessories it runs. Now you can imagine it’s important for the belt to be tight, so there’s a tensioner pulley on your engine that puts pressure on the belt to keep it at the right tension. The spring on the tensioner wears out over time so we recommend replacing the tensioner pulley at the same time as the serpentine belt. Replacing your serpentine belt on schedule, or when an inspection warrants it, will keep you from an unexpected breakdown.