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Actual factory fan clutch test

RichP

NAXJA Forum User
Location
Effort, Pa
I was looking for something else and they acutally do have a test for the fan clutch.
It involves drilling a 1/8" hole in the top of the fan shroud and sticking an 8" long thermometer, with a range of 0-225F, in the hole BEING CAREFUL TO CLEAR THE FAN WHEN IT TURNS. :D
Blocking the air flow with plastic or other obstruction in front then starting the engine, running it at 2400RPM for 10 minutes and observing and listening for the increased sound as the fan clutch kicks in and out. It is supposed to engage at 88C/190F and disengagement at 57/79C or 135/175F. Never noticed that section before. OH, and it should not spin more then 5 times when cold and spun by hand :D
 
Yeah, my FSM talks about that test. I decided that, given the price of a clutch, I wasn't going to mess around with somewhat dangerous practices like trying to measure exhaust air temp on the rad.

In practice, I wonder how many dealers actually do this test, versus how many just throw a fan clutch on the car and see what happens. I would bet the latter practice is almost universal.
 
I had also seen this test in my FSM and my fan clutch passed. You can also see it increase in speed when using a timing light pointed at the fan blades. However, while this test will tell you if if the fan clutch is engaging at the correct temperature, it will not tell you the VOLUME of air that the fan is pulling through - so it's not a 100% fool-proof test. I would recommend sealing the sides of the fan shroud with weather-stripping to increase the air-flow through the radiator.
 
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