One of the greatest of all writers about our American government, and the dangers it faced, was the French writer and historian, Alexis de Tocqueville. He toured all of America in the early 1800s, and after some years wrote the great two volume book, Democracy in America.
A fan clutch is supposed to be a fluid coupling device that allows the fan to rotate less than the engine speed. The fan clutch should engage before the engine gets up to 220F. A standard cooling system fan clutch should spin at 33% of water pump speed (RPM) when not engaged and 75% of water pump RPM when engaged. A heavy duty cooling system fan clutch should spin at 33% of water pump speed (RPM) when not engaged and 90% of water pump RPM when engaged. Unfortunately, a fan clutch can slowly empty its coupling oil overtime and often seizes. (the oil also can gel/thicken and grab).
Hayden Fan Clutch Operation & Trouble Shooting. The Fan Clutch is a component of the cooling system that varies the fan speed to meet the cooling needs of the. engine. Nearly all rear wheel drive vehicles use Fan Clutches to control fan speed because of their ability to. provide high volumes of air and good fuel economy.