Given its importance in the smooth and reliable running of your engine, it's worth taking a look at the timing belt every now and then. Even a simple visual analysis should be enough to give you ample clues on whether you need to replace it anytime soon. Start off by looking at the surface of the timing belt. Then, check to make sure that there are no oil, grease, grime, or other contaminants that could eat away at the rubber. Also, ensure that there aren't any cracks on the belt itself. Once you're done doing that, look at the underside of the belt, and inspect the timing belt's teeth. See if any of the geared teeth are missing or have been damaged in any way.