What Does the Fan Clutch Do?

[Bambikiller240]

The fan will ALWAYS SPIN. It should do so. The viscous fliud inside it allows it to operate like Mark B indicated. It is engaged more when cooling is needed and less when cooling is already sufficient. It will NEVER be stopped unless the engine is not running.

There is an article in the Tech Forum describing rebuilding and if I remember correctly it also has a bit of info on the operation.

[TomoHawk]

Ok, so then how do you know if the clutch is working right? Can you spin the blades with the engine off or something?

[sblake01]

You can spin the blades with the engine off. Also, the fan locks up when the engine is cold because the oil is cold. As soon as the oil warms sufficiently, the fan will slip until lock up is needed based on temperature. I don't really get the gist of this thread. Is your car overheating?

[sblake01]

Originally posted by Zrush

The fan clutch keeps the fan from spinning to fast so it won't break up into a million pieces.

Vicky

That really isn't true. My 320 has no fan clutch. Nor did the roadsters as well as other non-Datsun cars I've owned.

[TomoHawk]

Originally posted by sblake01 Is your car overheating?

Nope. I thought I could free up some Hp if the fan was free-wheeling until needed to cool the radiator, like while stopped in traffic.

On the highway, there should be enough air through the radiator to keep it cool, so airflow from the fan isn't needed.

[Bambikiller240]

"Lock-up" is a relative term in this discussion. The fan never "locks up" solid so that you cannot spin it by hand.

If you want to "try" to free up some horsepower ( I doubt you'll notice any difference unless you really "flogg" the car around an autoX or racetrack), remove the fluid coupled fan and go to an electrically operated fan.

[Bambikiller240]

Originally posted by TomoHawk

Ok, so then how do you know if the clutch is working right? Can you spin the blades with the engine off or something?

READ!

[Gee]

What is a clutch-type fan?

[tanny]

For those of you worried about fan vs horsepower: You actually can get more power at high rpms if the fan clutch is defective and locks up. The fan then acts like an airplane propeller and helps with thrust.:classic: Victor.

[Gav240z]

I took this from Zgarage easier than retyping it and pretending I'm the all mighty know it all :cheeky: .

ENGINE FAN CLUTCH IS LOUD

This is when you car sounds like a hovercraft when accelerating. The round, finned viscous fan clutch is seized.

But rather than spend bucks on a new or rebuilt one, fix it yourself. Simply take the fan and clutch off the car, unbolt the two halves, tap them apart, spray it out with brake cleaner, and refill the deeper half with 90 weight gear oil. The original oil dries/leaks out over the years.

But don't worry, it's not full of springs or anything, it a simple design and bolts back up easily. Did it on mine and it went from almost seized to spinning freely. A better fix is to simply take the whole assembly completely off. You can then add electric fans on the radiator. This will free up a couple of horsepower, and make the engine rev much more quietly.

http://www.geocities.com/zgarage2001/probs.html

[TomoHawk]

My (fan) does sound like a 'hovercraft' when the engine runs. I kinda thought it was partly engine noise. I gave mine a wing just now and it did spin just a little. I would take it that mine could use an overhaul, but isn't like new.

Also, I read somewhere that you should use "toyota silicone oil"? Don't remember where or which oil tho.

[mdbrandy]

Also, I read somewhere that you should use "toyota silicone oil"? Don't remember where or which oil tho.

If you read the tech article that Carl (Bambikiller) posted a link to a couple posts ago, you'll know exactly which Toyota silicone oil, including the part number.