Viscous Fan Clutch

[mestalla]

Hi. Anybody knows how to test the right fucntion of the Viscous Fan Clutch. I had an over heating episod last week when I was driving my Disco 1. Coolant seems to be running on system so I think there is no problem with radiator clogged or water pump damaged. I have my doubts about fan cluch is working properly. How could I test it?
Thanks in advance for your help!

 

[LRflip]

stick a piece of stiff cardboard in the fan while it's running.

If you can stop it, its probably bad.

I think Ive seen a gatorade bottle work too.

 

[bmn1965]

Rolled up magazine works well!

 

[ptschram]

Let the truck run to op temp. Shut it down. If the fan freewheels, it's toast.

 

[CandiMan]

Most viscous fan will engage in lockup when a cold engine is first started. You can hear the fan turning. Both my Disco and Chevy did that. About 30-40 seconds after start up, I can hear the fan disconnect. That's just a FYI

As PT mentioned, you will have to check the turning resistance of the fan compared to a cold and hot engine. Before you start the engine in the morning, turn the fan blades and try to remember how hard/easy (resistance) it is to turn the blades. Drive the truck on your daily routine and re-check the fan as soon as you shut it down. Not 10 minutes, as soon as you shut it down. If the resistance of the fan is harder compared to a cold engine, it's probably safe to assume your fan is working.