The drivebelt(s) are located at the front of the engine, and their good condition and proper adjustment are critical to engine operation. Due to their composition and the high stresses they endure, drivebelts stretch and deteriorate over time, necessitating periodic inspection. With the engine off, open the hood and locate the drivebelts, using a flashlight to check for separation of the adhesive rubber, core separation, severed cores, cracking, or worn ribs. Inspect both sides of the belt by twisting it to check the underside and feeling for any damage. For four-cylinder engines from 2001 to 2006, check the tension by pushing on the belt halfway between the pulleys; it should deflect approximately 1/4-inch, while other models have a self-adjusting tensioner. To adjust the alternator belt, loosen the lower mounting bolt and upper tension bolts, then carefully tension the belt and tighten the bolts. For power steering pump and air conditioning compressor belts, loosen the lock bolt on the tensioner assembly and adjust the tension using the adjacent bolt before tightening the lock bolt. When replacing belts, remove any interfering components, release tension, and slip the belt off the pulleys. For engines with a self-adjusting tensioner, use a breaker bar to release tension before removing the belt. Always take the old belt to the parts store for comparison and ensure the new belt fits properly in the ribbed grooves of the pulleys, adjusting as necessary. It is advisable to replace both belts simultaneously if they tend to wear out together, marking each belt and its corresponding pulley groove for proper installation.