How to test fan clutch?

[Troy P.]

I used to know how to test to see if the fan clutch on my '63 360hp was working correctly But age has taken its toll on the greymatter. Can someone refresh me on this?

Seems to me the fan should spin freely when the engine and radiator are cold and the fan is not needed to pull in cool air. But then I seem to recall it should spin freely when hot at high RPM to save horsepower and reduced noise.

[Zigmont M.]

Re: How to test fan clutch?

I have the same question and was wondering if someone could chime in?

[Tim T.]

Re: How to test fan clutch?

Should spin freely when cold and add'l cooling not needed. Should nearly lockup when hot to force more air through radiator.
OEM fans have asymetrical design to minimize noise

[John D.]

Re: How to test fan clutch?

I prefer to drive my 67 small block with the former GM part number 3916141 replacement clutch whick looks very close to the original.
I have the original Schweitzer bar type in a box for judging.

[Dino L.]

Re: How to test fan clutch?

What is the current GM available replacement part number for the clutch? for C2 small block

[John H.]

Re: How to test fan clutch?

What is the current GM available replacement part number for the clutch? for C2 small block

Dino -

It used to be GM #3916141 (Eaton), but it went out of production about two years ago; most of the vendors carried it, but they appear occasionally on eBay these days.

[Edward J.]

Re: How to test fan clutch?

What is the current GM available replacement part number for the clutch? for C2 small block

Troy, I don't have a part no. but you may still find a corvette vender that has one they where recently discontinued by GM and starting to get scarce.