[jschiller]

I am curious about the utility of running the fan when the engine is off.

My feeling is that you will receive only a minimal benefit of running the fans after shutdown since the only coolent circulation will be a small amount of cooler water in the radiator flowing from the bottom hose back to the engine block.

Or is it the hot water flowing from the engine to the rad via the upper hose thus cooling the heads a little that justify using a fan after shutdown?

I have always been puzzled why the car makers bothered with it. Now, fans and an electric water pump would be a different story.

John