On my 76 280Z when I have the AC fan on #4 which is high, after about 10 minutes the motor starts whining. If I hit a bump in the road or turn it down to #3 it will stop whining for awhile.Does this sound like the bearings in the motor going out? If so should I stick to a Nissan replacement or an aftermarket. I don't even know if I can still find a new Nissan. Thanks

I'd try removing it and cleaning/lubing it first. 74-78 motors produce a pretty good air flow compared to the earlier ones. 27175-U0100 is the number. I purchased one in 2000 from Nissan but I'm not sure if they would still have them.

Yep your bushings are dry/worn. Lube then and that will take carof the noise for a while. Depending on how long this has been happening and how ;omg the fan has run while howling, it may be time for a new one, or to take the motor to an ALternator/Starter shop fpr a bushing replacement.bearing upgrade. The last time I had one done it was $30 to have bearings put in. the fan was less noisy and put out noticeably more air(even over the output of a non howling fan) as well.

Will