If an Infiniti engine exhibits an apparent drive belt noise, follow the flow chart (seen here) to determine the cause.
AUTO TENSIONER INSPECTION
Example: Max angular pulley movement (mm)
FX45, M45 VK45 (Alt) 7
FX45, M45 VK45 (P/S) 13
FX50 VK50 (Alt) 7
FX50 VK50 (P/S) 13
QX56 VK56 7
EX35, FX35, G35, M35 VQ35HR 16
G37 COUPE, G37 VQ37 16
1. With the engine running at idle and the AC turned on, observe pulley angular movement (side-to-side). Visual comparison of movement with a known good vehicle is recommended. Refer to Figure 1.
2. With the engine running at idle and the AC turned on, observe the pulley axial/lateral movement (back and forth). Maximum movement specification is 1mm. Refer to Figure 2.
IDLER PULLEY/MANUAL TENSIONER INSPECTION
No more than 1mm of pulley rock should be visible. Refer to Figure 3.
ALTERNATOR ONE-WAY CLUTCH PULLEY INSPECTION
NOTE: The following steps can be performed while the alternator is installed on the engine if the drive belt is removed and the alternator electrical connections are disconnected.
1. Secure the rotor using a medium size screwdriver and a rolled shop towel.
2. Turn the pulley clockwise when viewed from the front. The pulley should be locked. If it rotates in both directions, replace the alternator.
3. Turn the pulley counterclockwise when viewed from the front. The pulley should turn with some dragging. If it locks or has unusual resistance, replace the alternator.