Yes, I plan to do that to see what temps are like.

However, I want to:

• Know more accurately with some specific data whether fan clutch is good or not, and that can be verified by seeing how much coupling it has when cold (upon first starting up in a San Diego morning - BRRR- LOL!) and at normal operating temp, And
• Verify, after I replace fan clutch, is it any better than original? (FSM method is pretty impractical I think.)

Nice method but still does not give us more or less exact figures at cold-start and at normal operation temps.
Yep, that's why an after-market gauge makes sense. (I'm still researching for one that has contacts that will close at certain absolute limit to trigger buzzer and/or flashing light- that might have to be an industrial controls caliber gauge.)

Below is what I have in mind...
A major safety concern is could there be 100% coupling (absolutely no slippage) that the fan will yank the gauge out of my hand or from where it is mounted? WOuld appreciate your thoughts.

 

Hey RAD, could you accomplish the same thing with a hand-held tachometer? I have a little laser one that reads a piece of shiny tape that you put on a pulley or shaft. If you know your fan pulley speed then you can watch your fan speed and see how much it is slipping.

 

Thanks for that idea! Yes, that's another good measurement method. Too bad I don't have that tool.

 

Here's what I've got:

 

You're Da Man! Now, that's the safer way to go. Ordered Thank you, Rustbucket!

 

Does the FSM specify a test for the fan clutch?

 

Nope; Just says to inspect for damage and/or silicone oil leakage.