Task: Changing Alternator/Water pump/AC compressor (serpentine) belt and Power Steering/Oil pump belt
Time: About 30 minutes
Tools Needed/Supplies Needed:
1. Jack/Jack stands/Ramps/Wheel chocks (some guys have stated they can change both belts from above, I changed the longer one from above and the smaller one from below) YMMV
2. 10 mm socket and socket wrench: to remove the lower engine cover/tray and upper air intake piece
3. 12 mm socket, to remove small canister for more room to maneuver upper belt on (see pics)
4. 14 mm socket and longer handle socket wrench to pull back (rotate COUNTERclockwise) on the belt tensioners to release pressure off the belts
5. (2) 6 mm allen wrench to insert into hexagonal holding bosses to lock the tensioners in place
6. Belts: Alternator/Water pump/AC compressor belt is the longer one (Infiniti part number: 11720AR010-57) effective length is 77"
Power steering/Oil pump belt is shorter (Infiniti part number: Product Code: 11950AR00A-56) effective length is 37.25"
I used Goodyear Poly-V Gatorback belts that I bought from Rockauto.com
Alt/Water pump/AC belt (part #4060770): $7.97
PS/Oil Pump belt (part #4040372): $14.10


Process:
1. Overall Diagram


2. Place front of car on jack stands/ramps and chock rear wheels
3. Remove engine covers and upper air intake piece. Remove lower splash shield/tray.


4. (Optional) Remove this canister - gives you a little more room when you're putting the belt back on (Tools needed #3)

5. Use 14 mm socket to turn pulley nut COUNTERclockwise to release tension on pulley. WARNING: DO NOT turn the nut clockwise, because you will loosen the pulley and the entire auto-tensioner assembly will have to be replaced.
The red arrow points to the pulley nut


6. As you release tension on the belt, the holding boss holes should line up and you can insert the 6 mm allen wrench in to lock the tensioner in place. (you can see the end of the allen wrench sticking out in the picture below)

7. Remove the Alternator/Water pump/AC compressor belt
8. Use 14 mm socket on the hexagonal protrusion part on the lower pulley and turn COUNTERclockwise to release tension on pulley

You can see the hexagonal protrusion part in the middle of the lower pulley assembly in the pics


9. As you release tension on the belt, the holding boss holes should line up and you can insert the 6 mm allen wrench in to lock the tensioner in place. (The holes on the RIGHT hand side of the lower pulley assembly)
10. Remove the Power steering/Oil pump belt
11. Install new belt making sure all the ribs and grooves are aligned. You can get a little more slack in the pulleys by turning the hexagonal protrusion nut COUNTERclockwise. You will also have to turn the nut COUNTERclockwise to get the allen wrench out once the belt is back on.
12. Back on top, install Alternator/Water pump/AC compressor belt, again making sure all the ribs/grooves are aligned. You will probably need to turn the pulley nut COUNTERclockwise again to release tension on the pulley so you can slip the new belt on. The new belts haven't been stretched, so it is a TIGHT fit and you'll need that extra slack. Once again, you will need to turn the nut COUNTERclockwise to remove the allen wrench out of the holding boss holes to unlock the tensioner.
13. Double check all the belts are on straight and lined up...you're DONE!!
14. Comparison of OLD belts vs. NEW
New on RIGHT, old on LEFT

New on TOP, old on BOTTOM

Ilya, will you put this in the DIY section?
thanks,
Craig