Hey,

I've been reading up on the clutch fan (yes i used search)
I've always had a noisy clutch fan, when I drive down a street people turn around looking to see what the hell that noise is.

So after reading some stuff I'd like more information on how the clutch fan works. Mine makes the same noise and blows the same amount of air whether the engine is cold or hot, day or night. Am I to understand this isn't right?

So:

2 Questions:
1) How does the clutch fan work?
2) Do I need a new clutch for the fan?

Cheers,

renegade334

the clutch fan is a viscus fluid type,,it senses the speed of air moving over it and adjusts the fluid thickness to suite its needs,,IE: if it needs more air it thickens the fluid.

yes a new clutch will be needed.

you will have others tell you to change over to thermo fans,,but while they are good sometimes its just not worth the time and effort.

shame your in Melbourne,,i have two complete fans including blades ready to fit,,,

hope this helps

you are half right

viscous fluid yes it does not sense the speed of the air ffs

when the rad heats up the air flowing over the clutch fan hub is warm and warms the fluid inside it allowing the fan to spin
hence when the rad is cold the air over the clutch fan is cold and slows down the speed of the fan

well half right ffs

i said that hahaha

I'm not sure that there's even been half right yet. Viscous couplings have the unusual property of generating more friction the hotter the fluid gets.

I don't think the heat from the radiator makes much difference in the overall scheme of things, but anyway, the hotter the radiator is, the hotter the coupling will be, and therefore the stiffer you want the coupling to be so it pushs more air. You want it to push more air because the radiator is hot, meaning the engine is hot. A viscous coupling will do this.

The following are what i see as being pertinent:

Scenario 1, You hold the revs at 5500rpm while the car is stationary. The motor will generate some heat doing this, yet there is no natural air flow through the radiator and engine bay. So you need to the fan to flow heaps. So you need the coupling to be stiff. The coupling will be stiff, because the motor is spinning the axle fast and the natural airflow is low providing a lot of resistance, which heats up the fluid and makes it stiff. This scenario is the biggest test of the coupling, placing the most stress on it.

Scenario 2. The revs are steady at 1500rpm while the car is travelling at 100km/h. The motor will generate a moderate amount of heat, and there is a lot of natural airflow through the radiator and engine bay. Because of the airflow you don't need the coupling to do all that much, but you still want it to do some work. Because the revs are low and the natural airflow high, there will be a low amount of load on the coupling, and thus it won't have stiffened up much, and won't overcool the motor or waste energy.

I thought heat is transferred at least in part because the clutch is directly bolted to the pump shaft.. which is stirring your coolant..

we all know that metal ain't bad as a conductor of heat.. and 3 inches of metal shaft between the radiator coolant in the water pump to the clutch has got to transfer a decent bit of heat.

more heat, more friction more spinnies...

Our other car.. (Toyota Surf Hilux turbo diesel) is known for dodgy fans.. though these have a piece of metal that is heat reactive and locks the fan completely at a certain point so there is no slip. The metal fails and the viscous fluid needs a refill and the fan doesn't spin enough.. next thing you know.. cracked head. much pricier on a hilux diesel than a falcon.

if wot im reading is correct mine is noisy and blowing clouds of dust at all times so its stuffed..how much would you charge for one of youres?

about $30 plus postage.

but i'd have to check em again,,there in the in-laws shed..

i'll get back to ya

i got three words... "Thermo Fan Conversion"

exactly. i picked up some EL thermos yesterday. fitting them today

not every one wants to go throught the hassle of thermo fans

at least with the clutch fan its just take radiator out,,undo old clutch fan put new one on,,replace radiator taking advantage while its out to clean it all and reverse flush it.

why is it a hassle
hook it up to a switch in the cabin. done

not quite the right way,,nuff said.

Thanks for the replies guys,

Yeh i'm probably going to get thermos eventually, but I have to wait until the cash flow starts again.