Viscous Fan Coupling

[GlennW]

I've got the stock cast water pump pulley & metal fan. Viscous coupling is original as far as I know, with the "Patented in United States Patented in Canada 1961" cast into the front hub. Without the unit mounted to the pump and no fan on it for leverage, it turns smoothly by hand but with decent resistance. Is there any definitive measurement on how it should "feel" ? I have no idea what a new one feels like, should it turn really easy by hand and only have resistance from the inner fluid at higher RPM? No cooling problems with it-rock steady 180° withing normal driving conditions, but I have the water pump off for replacement so if there's a need for a new coupling it'll only take maybe 10 minutes to swap it out so I'd rather do it now if deemed wise based on some actual tactile spec. Thanks.

[Gunslinger]

It doesn't sound like you have a problem. Basically...if it ain't broke, don't fix it.

The best way to tell if a fan clutch is operating properly is in the car. When the engine is up to normal temperature, shut the engine down. The fan should stop spinning almost immediately...after a few revolutions. If the fan keeps spinning, then you know there's a problem.

[GlennW]

Yeah, that makes more sense, the unit was at about 75° when I took it out of the car so of course it won't feel like it does when at operating temp. Good catch, thanks. It does spin down pretty quick when shut down after normal driving and it has no signs of leakage so back in it goes ☺