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Nissan still used a clutch fan on the Z cars, and probably on some of their trucks (not sure about the trucks).
One thing to consider on the clutch fan is when it is not needed the airflow over the fan could actually reduce the load on the engine to drive the water pump amd the fan, to the point where there might not be any losses at higher speeds (speculation).
I have seen cars driven with broken water pump belts, where the clutch fan was actually providing enough coolant circulation to keep the engine cool. One time on my Z car the water pump belt broke and I limped home using pulse and engine off glide to get 6 miles back to my shop to replace the belt. When I got there the coolant temperature was actually lower than normal.
The clutch fans are controlled by a valve actuated by the small bimetallic spring on the front of the fan, which changes the valve restriction inside the fluid coupling depending on the temperature of the air flowing through the radiator.
I used to demonstrate to customers when their (clutch fans) were worn out by wrapping my hand in a shop rag and stopping the fan blades from spinning and actually spinning them backwards while the engine was running (definitely not recommended).
When they were worn out the customer complaint was overheating at idle.
On a lot of cars, like my 95 Riveria the radiator is angled at about 45 degrees to the vertical and you almost never heard the electric fans come on. I would attribute this to the fact that the angle of the radiator would allow air flow to increase when the vehicle was not moving and reduce the necessity for any fan operation.
I never heard of the electric fan creating electrical current from the air moving across it and turning the blades, making it a generator. Thats neat. I wonder if it actually happens on a regular installation, but I doubt it.
regards
Mech
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