WARNING: This page is about a different car, the 2004 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.
Check for badly rusted or corroded water pump body assembly.
Fig 1: Checking For Badly Rusted Or Corroded Water Pump Body Assembly
Courtesy of NISSAN MOTOR CO., U.S.A.
Check for rough operation due to excessive end play.