Viscous fan drive

Hi,

FSM says one should replace viscous fan drive, if it spins more than 5 revolutions when spun by hand on a cold engine. FSM tests for proper engagement, but what if the clutch does not disengage ?

Mine does not rotate more than 30 degrees after I remove my hand.
Does it mean It makes sense to change it for the sake of highway mpg ? How much your spins when cold ?

Thank you,
Andrey

Get a dealership fan clutch, that's all I have to say.

The aftermarket ones are sometimes larger (especially if they have the radiator eating "fins). And they don't work as well.

OEM is always more fine tuned for your particular vehicle!