1993 240sx: What is the theory behind fan clutch?

[surreybc]

I have no idea how the stock clutch works? does it respond to temperature? thanks.


My fan will only spin 6 inches when I rotate it as hard as i can. My last water pump lasted 6 months. I hear crazy belt squealing below 1500 rpm. never seen the fan stationary. i cant be this stupid.

[airhead]

might be a wire or somethign in the way thats not letting it spin look around

[SexPanda]

get rid of that shit, get some electrics from an altima or soemthing... Easy fix.

[!Zar!]

get rid of that shit, get some electrics from an altima or soemthing... Easy fix.

You're kidding me...right?

Stock clutch fan with shroud works better than efan setups.

The stock clutch fan isn't supposed to stop moving one the engine is started.

It starts just how it's name implies...

Pretty much once the engine starts the clutch fan starts.

Nothing wrong with that.

If the fan STOPS spinning, then something is wrong.

[SexPanda]

You're kidding me...right?

Stock clutch fan with shroud works better than efan setups.

The stock clutch fan isn't supposed to stop moving one the engine is started.

It starts just how it's name implies...

Pretty much once the engine starts the clutch fan starts.

Nothing wrong with that.

If the fan STOPS spinning, then something is wrong.

lol i was kidding. You should be able to move the fan when the car is off though. It should more or less spin freely. If you cant spin it with the car off, which is what I THINK your getting at, then you might have a problem.

IDK about the s chassis clutch fan, but most are viscous. If you cant turn it with the car off, its seized, putting alot of stress on the water pump. You should be able to stop the fan with your fingers with a proper working viscous clutch fan, when the car is running.

does the car stay cold too long? And if you hear a squeeling... Im almost positive its your fan cluch seized. Its squeeling because the fan is running at full engine speed, not a fraction of it like it should when its working properly.

lol super edit.

[g6civcx]

I have no idea how the stock clutch works? does it respond to temperature?


Come on, guys. Some clutch fans rotate with engine speed regardless of temp. Others have a temp switch that will disengage the clutch and allow the fan to freewheel to help bring the engine up to temp.

I do not believe your car has a temp switch unless it has been modified. The stock fan clutch is just a one-way clutch that forces the fan to rotate with engine speed, but also allows the fan to overrun the engine speed if you're on the freeway.


Some of the comments are outside of the scope of your question, but deserve a response.

I recommend leaving the stock clutch fan and shroud if possible for better cooling.

[surreybc]

lol i was kidding. You should be able to move the fan when the car is off though. It should more or less spin freely. If you cant spin it with the car off, which is what I THINK your getting at, then you might have a problem.

IDK about the s chassis clutch fan, but most are viscous. If you cant turn it with the car off, its seized, putting alot of stress on the water pump. You should be able to stop the fan with your fingers with a proper working viscous clutch fan, when the car is running.

does the car stay cold too long? And if you hear a squeeling... Im almost positive its your fan cluch seized. Its squeeling because the fan is running at full engine speed, not a fraction of it like it should when its working properly.

lol super edit.

The idle acts like it is not getting enough air on cold mornings but only after the air regulator cuts out. It does seem to take too long to warm up but that might just be my impatience. It will be interesting to see what happens when I change clutch. thanks.

[projectRDM]

Come on, guys. Some clutch fans rotate with engine speed regardless of temp. Others have a temp switch that will disengage the clutch and allow the fan to freewheel to help bring the engine up to temp.

I do not believe your car has a temp switch unless it has been modified. The stock fan clutch is just a one-way clutch that forces the fan to rotate with engine speed, but also allows the fan to overrun the engine speed if you're on the freeway.


Some of the comments are outside of the scope of your question, but deserve a response.

I recommend leaving the stock clutch fan and shroud if possible for better cooling.

Bingo. End thread.

[murda-c]

It's a viscous clutch, when it heats up it gets stiffer.

At low temperatures the fan clutch will allow more slip, allowing the fan to spin slower than engine speed, as it heats up, the clutch transmits more torque, spinning the fan faster. If the clutch is seized, you will get belt squeal and excess water pump wear.

[surreybc]

Thanks for the replies . Here is a video on testing the viscous clutch. DONT DO THIS. DANGER. I think it should spin about half way around when spun manually. spinning might depend on if engine is hot or cold. viscous clutches are themostatically controlled. have to look up thermostatic

YouTube - e34 m5 viscous fan clutch test (http://www.youtube.com/watch?v=YJXtYZeyED0&feature=related)

[Slidin240Wayz]

I have a sr clutch fan for sale if your interested.

PM me

[ZX88]

clutch fan > electrics any day especially on the track. i don't overheat and im not even running a fan shroud.

[SoSideways]

Do all of you that are throwing the banter "clutch fan is best!!!" even have any scientific proof that it works better?

SR20DET Radiator Test (http://home.satx.rr.com/nissanweb/RadTest/RadTest.htm)

The clutch fan's sweet spot is 3000rpm, after that, it pretty much nose dives into "it doesn't do jack shit", especially if you're in an environment where you have poor ducting on the car, and aren't going particularly fast, like drifting.

A properly ducted and installed electric fan setup would be cooling your car even if you were at 7000rpm and going like 30mph.

Bet you if you put the clutch fan equipped car in a situation where it's just sitting there at 7000rpm and going 30mph, that the temp would start to rise pretty quickly.

[civilized_drifter]

f-a-l ftw
http://i78.photobucket.com/albums/j91/STidragster/black%20hatch/DSCF1629.jpg

[Slidin240Wayz]

Do all of you that are throwing the banter "clutch fan is best!!!" even have any scientific proof that it works better?

SR20DET Radiator Test (http://home.satx.rr.com/nissanweb/RadTest/RadTest.htm)

The clutch fan's sweet spot is 3000rpm, after that, it pretty much nose dives into "it doesn't do jack shit", especially if you're in an environment where you have poor ducting on the car, and aren't going particularly fast, like drifting.

A properly ducted and installed electric fan setup would be cooling your car even if you were at 7000rpm and going like 30mph.

Bet you if you put the clutch fan equipped car in a situation where it's just sitting there at 7000rpm and going 30mph, that the temp would start to rise pretty quickly.


I had e-fans last year and would hit 110 nearly every time out on the track and I would spit alot of coolant.

I had clutch fan this year and I hit 110 a handful of times.

I also upgraded to a Nismo t-stat, so that had something to do with it, but I still prefer the clutch fan.

No burnt fuses, wires, etc. It's always working.

[surreybc]

I tested it when it was cold and it only would spin 6 inches. Put a rolled up newspaper on fan as it rotated at idle and fan was going fast enough to cut through plywood.
Ill make a video with old and new clutch. need to stop reinventing the wheel.