By now, we all should know what could happen if our timing belt snaps, but what about the timing belt's partner in crime, the serpentine belt? Serpentine belts are the overachievers of the engine bay. One long rubber loop can control everything from your alternator to the air conditioning compressor to the power steering pump. It's basically the multitasking intern of your engine -- doing a dozen jobs, never complaining, until it snaps and suddenly you're the one sweating.

Despite doing so much, most of us forget the serpentine belt even exists -- let alone that its tension matters. But it does. A lot. Too tight and it'll grind bearings to dust. Too loose and you're listening to the high-pitched scream of rubber slipping. That's why even a faint squeal or mysterious under-hood smell deserves your attention before your engine accessories go on strike. However, how do you diagnose the problem, and even more, how do you prevent any issues from happening?