Thermal fan - Great Lakes XJ

ingin

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Posts: 9

Date: Oct 14, 2011

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My thermal fan is quite stiff to turn when cold, but at operating temperature, it spins very easily ie. there is virtually no resistance when hot. I thought it should be the opposite, easy to turn when cold (spins) and when hot should be resistive or stiff to turn. Can anyone advise if I am correct . Thanks Ian __________________ Ingin

Comet #2

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Date: Oct 20, 2011

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Initially the fanclutch will be stiff to rotate for the first few revolutions ,,,

Once the oil has dispersed inside the clutch due to rotation ... the clutch action is reduced.

Proper operation of the fan clutch is dependant on the air temp behind the radiator ... The thermal spring requires an air temp of about 170*f / 75*c to fully engage the clutch at its 50 to 70 percent of engine revs.

Expect the fan to be easier to spin once the vehicle is stopped with the hood/bonnet up .... as no air is flowing/being drawn thru the rad ... and the engine bay temp lowers toward the ambient.

Section 7 in the FSM covers general operating and testing procedures ... but a look at info on some of the fanclutch manufacturer websites ... fills in some of the blanks.

Fanclutches fail .... its a fact of life .... so a new one every few years is a good plan unless you dont do many miles.

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ChevelleSSLS6

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Date: Oct 30, 2011

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I run 2 factory electric fans just fine. Get the 1996 and newer ones (curved blade moves more air, older ones look like normal fans) __________________ My Fleet 1996 XJ "Snowball"- 3.5" lift, bunch of little mods. I hate pegleg rear axles! 1974 AMC Javelin "Jade Grenade"- 360v8, 4sp, green inside and out. Underfunded Project. 2009 Kawsaki Vulan 900 "Rocket III"- Summer DD

Topic: Thermal fan