Located at the front of the vehicle, the drive belt(s) are essential accessories for the function of the engine, by rotating various parts, including the alternator, power steering pump, water pump, an air conditioning compressor, and supercharger for the ZL1 models. There are different layouts according to year of engine, from one to several belts, for which it is necessary to monitor the degree of wear due to their operational purpose and material. One is self-adjustable and by observing wear indicator marks on the tensioner body adjustments can be done visually; if the indicator mark is outside the working range then replacement is required. To look through all the length of the belt it has to be rotated by turning the engine and with this movement checking for cracks, fraying and glazing of the belt surface as well as to check for damage on the pulleys. Minor cracks on the ribbed belts are allowable in essence as long as the cracks are not intensive or overly deep in this case; the belts have to be replaced. For V6 engines, this means having to remove not less than the air intake duct and the resonator in order to release tension on the drive belt and replace it. V8 engines are the same as the above, with different procedures for 2011 and earlier models, and 2012 and later models including the supercharger drive belt. The air conditioning compressor drive belt can only be unbolt since it has to be slit so as to emplace the new conveyor belt into proper position and must fit the pulley grooves correctly. The drive belt tensioner can be removed by unbolted from the engine; conversely, installation is done by the reverse of removal while making sure that all bolts are tightened to the recommended torque.