Does anyone experience a fan clutch that is not locked when idling? Such as they do in big rigs ans whatnot; the fans just kinda sit there or turn very slowly like the clutch is FULLY disingaged. When our clutches are unlocked, how fast do they turn?
Kevin, I did some testing about a year ago. Here's some notes I wrote down:
The temperature measured below was from between the radiator and fan using a digital thermometer. RPM was measured with a optical tach. Ambient for both tests was ~67 F.
Ford-Eaton (22 years young):
Full engaged 180 F air with 1550 RPM @ pump and 1505 RPM @ fan
Full disengaged ~115 F air with 1600 RPM @ pump and 405 RPM @ fan
Note that disengagement temp was significantly lower then the newer model. It may actually have a slower reaction time and some delay.
4 Seasons 36963 (the $53 special)
Full engaged 177 F air with 1590 RPM @ pump and 1535 RPM @ fan
Full disengaged 145 F air with 1710 RPM @ pump and 415 RPM @ fan