Put the car on the hand brake so it does not budge when you will do the job. Check whether the engine is muted and removed if the ignition key. Also don't forget to disconnect the negative cable from the battery terminals. Then carefully lift the hood and find the belt of the generator. First, check it for cracks, tears, or excessive elongation.
Grab a caliper or a ruler and hit on the belt in the direction of its contraction. Much pressure is not necessary, normal stress in three-four kilograms, which can be achieved, if you press your thumb to the average power.
Holding the belt in the pressed state, measure the distance at which took place deviation. If this value exceeds 10 mm, it is necessary to perform a tightening of the belt. Other indications of the normal belt tension is his turn only 90 degrees, which is performed with just two fingers. If it can rotate to a larger angle, then it is necessary to tighten the belt.
Take the Allen key 17 mm and use it to gently loosen the nut, which attaches the generator to a tension lath. Now, using an Assembly shovel or conventional pry, slowly remove the engine from the generator to such an extent that the belt is not enough stretched. Then, without changing position of the alternator, tighten the nut you just unscrewed.
Ensure that at commit time, the load remained the same, and the displacement of the belt from the desired position. For best result tighten the fixing nut with a torque which shall not be less than 30 N/m. Remember that it is recommended to check the belt tension after every 10 thousand kilometers, and if necessary before.