fan clutch test with cardboard?

[sodafeld1]

Some engine's fan clutch can be tested by getting the engine warm then testing to see if the fan stops by placing a piece of cardboard to stop the fan. If it slows or stops it can mean the clutch is on it's way out. Does this apply to the 2h fan clutch?

 

[pithicus]

Genuine aisin clutch and fan lock hard and really roar when they reach a certain temp if working properly. It's really easy to hear. At least the 2f/3f ones do.

 

[sodafeld1]

mmm, yes it does really roar when kicking in usually. Normally my temp is rock solid stable, but of late towing heavy loads up steep hills over 30c ambient, I get the temp needle moving not to half way but heading there. Wondering if my fan clutch is starting to fade..bit of black gunk building up just besides the altenater on the front of the block, perhaps where viscous fluid may leak. I usually keep engine bay pretty clean. That's a guess though.

 

[pithicus]

Roaring's a good sign. As long as you can clearly hear it, it's probably working good enough. Some cheapo clutches, or fake aisin's, don't produce any roar at all. My 90 degree t-stat for my 3f makes my temp gauge sit exactly half way in any weather. The fan kicks in when just over half, then the gauge drops to 1/3, fan stops, then up to over half ,repeats the cycle etc. If your clutch is leaking, it's not a good sign though.