Does anyone know how to check the silicon clutch on the mechanical fan of my "7,,928? Do you just observe if the fan speeds up when the engine warms up?

 

The fan should stop quickly when you turn the engine off when hot, and have some resistance to manual turning when stopped, depending on temp. If it freewheels readily, it needs silicon.IMHO its cheaper to go straight to electric fans. If you must, buy some Toyota silicon, do a search here on how to get it inside the clutch.
jp 83 Euro S AT 52k, BTDT

 

Toyota silicon fluid cost me about $20.

Its also possible to fill them with a less expensive silicon fluid. Its used for the gearsets on radio control model cars.

 

With the engine warm, open the hood and use the throttle cable on the front corner of the engine to raise the engine RPM to about 2,000 - 2,500 and hold it there for ten seconds. If you do not get a very noticeable blast of hot air after a few seconds, the clutch needs attention.

 

Thanks gents. Fan has checked out to be OK.

 

I replaced mine with a new fan clutch recently, and it's made a world of difference this summer.

If it's original, it's pushing 30 years old, and it is doubtful it is working correctly. I had a hard time telling from the tests . . .

 

Thanks, will keep in mind.

 

Isn't hard to refill one. I did it a couple weeks ago. Made a very significant difference in lowering my operation temperature at 40mph and lower. Should be some pictures here somewhere.