Scotty, I have a 2007 Nissan Frontier, 4Cyl, 2.5L. I am trying to find out whether the alternator pulley is an OWC (One-Way Clutch pulley) or an OAD (Overunning Alternator Decoupler pulley). From what I understand, the OAD has an additional spring which gives it a kind of shock absorber effect. I could try to figure it out by trying to turn the shaft, but that would require that I pry off the dust cap and I'm affraid I would probably destroy it in the process.
Well even I couldn't tell without asking the parts department at a dealer you give them your VIN number and they can tell you exactly what that vehicle came with.
Thanks Scotty. Unfortunately, the dealer only sells the whole alternator(rebuilt) with the pulley included and the pulley is not even broken-out in the parts diagram. The "mechanic" that I talked to at the dealer didn't really know for sure how the pulley worked. I ordered what is supposed to be a "new" alternator with included pulley from Auto Zone.
But it looks rebuilt to me and and the pulley is different in appearance and there is no identification on any of it except a stick-on paper label from Taiwan with AZ part number. So, I'm a little uneasy about putting it on. From my research, I understand that using the wrong pulley can be disasterous.