It seems my fan is always turning when engine is running. Engine off it seems to take a lot of pressure to move fan by hand. Should it turn easy by hand when not running or not?

 

No, it will be stiff when it's sitting. Usually it will turn and be locked when you first start the truck, and as the fan spins, the fluid moves to the correct places and it unlocks. Even though it is unlocked, it will still turn with the engine. The way you know that it's locked up and not working is it sounds like a 747 under the hood when you are driving down the road. If it's really noisy, then you have a problem.

 

Franklin's right, a loose fan clutch is a sign of a dead one. They usually loose their oil when they die; look for oil and dirt on the fan blades.

 

If there are questions about this clutch, and the fan is roaring, just replace the thing. I replaced the original on my '83 351W, and the underhood noise dropped drastically.

Good luck

 

Well okay seems mine is still good then. Thanks to all for answer.

 

There are two types of fan hubs, thermo and non thermo!! thermo of course uses heat
to engage. non thermo is always turning at about 60% slip. so if you have that one it
will always be making noise. Feel the center of the front of the hub if it has a little coiled spring it is a thermal unit if no then non thermal. I would change it to a thermal
unit when you get the cash to do it it will save some HP and be quieter, or you could
cut off the cat and run straight pipes.