remember the fan clutch

[harry3]

Defective fan clutches are a common and often overlooked cause of overheating. The shear characteristics of the clutch fluid gradually deteriorates over time, with an average loss in drive efficiency of about 200 r.p.m. per year. Eventually, slippage reaches the point where effective cooling is no longer possible and overheating results. (On average, the life of a fan clutch is about the same as a water pump. If one needs to be replaced, the other usually does too.)
If the fan clutch shows signs of fluid leakage (oily streaks radiating outward from the hub of the clutch), spins freely with little or no resistance when the engine is off, or wobbles when the fan is pushed in or out, it needs to be replaced

a faulty fan clutch may cause air cond problems too, by allowing the compressor to overheat and be turned off automatically, due to not enough air being drawn thru the air cond radiator

[vlv8vic]

another excellent post from harry3. Positive feedback posted buddy.

[jimrichards1964]

tossed mine put in a thermo out of a mazda, been fine since

[rb26dett]

I had a 16inch thermo and went back to a clutch fan

[ucwepn]

Hmmmm very interesting I have 2 spares so I might change it over. Are there any telltale signs of a worn clutch fan?

[harry3]

there will be noticibly less air being blown back if its not working properly, someone suggested poking a rolled up newspaper in the blades, a working clutch should cause the paper to be cut, if the fan stops, the clutch has had it

[vlv8vic]

can also work the other way, the clutch is there so the engine can rev up quicker without the fan spinning at the same rate, the clutch allows it to catch up with time.

You should be able to turn the fan with your hand (engine off!) without too much effort, but should not be able to free spin it.
sometime when you shut the engine down they might give a bit of a turn, only because they get warm and the fluid becomes less viscious. (sp?)

on the other hand, if they wont turn, or take alot of effort to turn with your hand then they are probably screwed as well. another tell-tale sign is fluid leaking from the fans clutch.

when mine died there was an almighty roar as i accelerated, the fan was spinning at the same rate the engine was revving because the clutch had lost its bearings, then fluid, then seized up.

[mag]

There are brilliant thermo fans on the market and theres some that couldn't blow enough air to cool even in a gale wind....

[mag]

The only way to check a clutch fan is to spin the fan (Engine off and Hot) mark a blade with tape or , give it spin by hand and it must not spin more than 1 an half turns!!! thats it, and as the clutch has a thermal spring in the middle it senses heat and adjusts to suit conditions....

If anyone's interested there's a thing you can do to feel and hear it working....