This part has been discontinued by Nissan and is no longer available.

New OEM S14 Fan Clutch.  Fits all 1995+ Nissan 240SX models

The OEM S14 fan clutch uses a viscous coupling to control fan speed based on engine temperature.  It's a good design but after 20 years of use, most are simply worn out.  Some fail by becoming too loose resulting in the fan spinning slower, often eventually resulting in overheating and catastrophic engine damage.  Others fail by locking down and spinning at full engine speed all the time.  When this happens the increased drag will rob considerable power and you will hear the sound of a lot of air rushing at idle and low speed.