Thread: Viscous fan hub How tight

Jase
The theory is that there should be a large degree of slippage when the engine is cold and that the slippage reduces as the coolant temperature increases. That doesn't however mean that the fan spins absolutely freely when cold. If you try and rotate it when cold there will be some drag from the fluid in the coupling. If you give it a good hard push in the direction that it should rotate then it will probably continue to spin for a half second or less before comimg to a halt.

Russell

see below

Originally Posted by rjhjstr

Jase
The theory is that there should be a large degree of slippage when the engine is cold and that the slippage reduces as the coolant temperature increases. That doesn't however mean that the fan spins absolutely freely when cold. If you try and rotate it when cold there will be some drag from the fluid in the coupling. If you give it a good hard push in the direction that it should rotate then it will probably continue to spin for a half second or less before comimg to a halt. no way mine would continue to spin on for a millisecond
you can turn it ok (with a little effort) but it dead stops when you let go no matter how hard you try to spin
Jase

Russell

Mine's not particularly stiff to turn, but it certainly doesn't freewheel, stopping when there's not enough pressure to keep it turning.
When refitting the fan after removal, the nut is screwed-on by turning the fan without the need for a spanner, so there's not much slippage.

You can wait for Richard (Kie4) to respond. It'll be fresh in his mind because he replaced mine this very morning.

We are hoping it was the source of my overheating under load problem.