Six-cylinder engine: Insert a hex key into the tension roller bolt. If available, first remove the cap from the tension roller bolt. Slowly turn clockwise to compress the hydraulic tensioner "1". Remove the ribbed V-belt.
Four-cylinder engine: Place a wrench on the tensioner pulley bracket and press it to the left. Remove the belt.
Apply a new V-ribbed belt according to the diagram shown, moving the tension roller all the way to the right, as when removing. Pay attention to the position of the grooves on the pulleys.
Unload the tension roller. The tension is determined by the tension element and is not adjustable.
(Read the original source on the website BMWMan.ru)