The replacement of the A/C compressor drive belt of the M73 engine is carried out in the same way as the replacement of the A/C compressor drive belt of the M60 engine (see section Removal and installation accessory drive belts). Below is only the procedure for replacing the alternator drive belt.
If you intend to continue using the belt being removed, mark the direction of its movement.
1. Remember the belt routing pattern on the pulleys.
2. Remove the cooling system fan drive coupling together with the impeller (see section Removal and installation the fan drive clutch Chapters Engine cooling, heating, ventilation and air conditioning systems).
3. Disconnect the cooling system hose from the engine, above the generator.
4. After loosening the nuts (Nos. 1-4), loosen the belt tension and remove it.
5. Check the condition of the belt (see chapter Vehicle settings and routine maintenance) and replace it if necessary.
6. Place the drive belt on the pulleys and rollers and make sure it is positioned correctly.
When installing a belt that has already been used, maintain its previous direction of movement.
7. Move the belt tensioner adjustment plate by the hexagon (5) until it stops and tighten first nuts 3 and 4, and then nuts 1 and 2.
The article was copied from an online resource: BMWMAN.RU