electric fan

Hey guys
I would like to fit electric fans. Please can I get some advice on what fans to get and if its worth doing the conversion... Could I do the job myself and what else other than the fan needs to be done and purchased??

Any advice will be appreciated
😀

http://www.200sx.za.net/phpBB2/viewtopic.php?t=33&postdays=0&postorder=asc&highlight=fan&start=0

Search and ye shall find

IMHO if the std stuff is working fine then leave it alone. Changing to electric fans just for the sake of it is a waste of money and leads to other issues.

I'm going with "The Calibrator"

On this, I have had nothing but sh$t with my electric fan swap.

let me be the one to start the argument again!

my electric fan swap has been nothing but fine. i've installed two 12 inch electric fans, they are switched by a bmw switch (available from spares dealers) that switches at two temperatures - 91 and 99.

originally i had one fan switched at 91 degrees, and the other at 99 degrees. then i had one switched on at 91 degrees, and the other by the aircon switch. now i'm switching both fans at 91 degrees.

BUT - i've removed my aircon system. thats the aircon radiator, piping and compressor. so my car seems to be running about 10-15 degrees cooler than it used to with that stuff installed.

however, mine is a different case study, and i've heard of other members not having enough CFM on the fans to cool sufficiently. so others have definitely had problems with this mod.

i've also modified my water housing to accept the BMW switch and the temp gauge sender unit. so things are different to standard when it comes to my engine!!!

Okay let me add my 2cents worth.
The thing to consider is that the viscous fan runs continously & the temperature of the car is controlled via thermostat.
So if you are adding electric fans, I suggest you ran the fans continous anyway.

Another thing to consider is that the standard fan is designed to shift a certain amount of air, so the electric fans should be able to shift more or the same.

All the eletric fan does, is really add more to the throttle response. The power is increased, but by a very slight fraction.

I had electic fans on my old SX without a problem & now I have the viscous fan on my current SX without a problem.

WooHaa wrote:

Okay let me add my 2cents worth.
The thing to consider is that the viscous fan runs continously

the viscous fan shouldn't be running continuously. it is connected to a viscous coupling. the material that fills the coupling gets more viscous the hotter it gets. so the temperature under the bonnet controls the amount that the fans turns. its basically a clutch!!! one that engages more the hotter the engine gets.

when its cold, it shouldnt be running much at all. i've seen cars that barely spin when the viscous coupling is cold, and you can stop the fan blades with your bare hands!!!

mine was running all the time, and that is why i replaced it with electric fans!!! its not supposed to run like that.

as for throttle response, unless your "butt dyno" is tuned way better than phinx's, you probably wont feel the difference... unless you're one of those guys that immediately thinks that the improvement in sound that their drilled airbox now makes, is a definite 10 - 15kw's on their little FWD slopel or golfie wheels!!!!!!!

hehehe - now that should summon a myriad of response!!!

O!!
My fans spins all the time. Even when it's very cold, & not slowly either.

You are worrying me a little here. The car has always been like this. I have seen other cars like mine as well (SX's) when you start the car from cold it spins quite fast...Don't think I wanna put my hands there.

Is anybody else's like mine as well? Maybe I should record a video & show you guys.

The fan is very quite but spins fast, The bearings don't make a noise & the fan doesn't wobble.

What you are saying is correct about a clutch & all that, but the SX does'nt have that. It should spin all the time as the temp of the engine is thermostat controlled. If you want to drop the engine temp, you don't spin the fan faster, you change the thermostat.

yeah my sx did that too... that's why i changed it to electric fans.

but my experience with other vehicles is that a VISCOUS coupling does just that. as it gets hotter it offers more resistance between the plates(?) so the fan starts spinning more.

it may not be the case with the sx, but as far as i know, a viscous coupling is what i just described. otherwise they shouldn't call it that.

also a thermostat is there to control temperatures, yes... but its there only to get the engine temperature up to operating specs quickly. it stops water flowing to the radiator at low temps, so that the engine warms up quickly, then it opens to allow water to the radiator, to keep the operating temperature constant.

thats also why you dont need the fan(s) to operate at low temps. because at low temperatures, if you have a correctly operating thermostat, the water wont even be running through the radiator!!!

a good test is to remove the thermostat and see at what temperature it opens. you can do this by placing it in a pot on hte stove, with a thermometer in it!!! check the temperature at which it opens. chances are its between 80 and 90.

so why bother using a fan to cool a radiator that isnt even involved in the flow of water until the engine temperature gets to between 80 and 90 degrees???

You are 100% correct VC, but the reason that Nissan & other cars like the 230 Kompressor run the fans continuosly, is because the water is used to cool the oil as well.
The themostat just controls water temp to the engine.
If the fans are used to control water temp only, then the oil temp gets to high.

I have had the oil get so thin it leaked through the seals of my turbo on my previous Nissan...Luckily no damage was caused.

I have noticed higher performance cars, run fans all the time, just for the above reason.

LOL - yeah you're also right.

actually this is quite constructive, cos i forgot about that totally. guess i'll go out and buy that oil cooler now!!! forgot that the nissans have that highly effective oil "heater" on our CA18det's!!!

but that also brings me to another mod that i wanted to do. and thats install an LED in dash to let me know when the fans are on, and install an override switch to turn the fans permanently on when i am drifting.

I have had electric fans for about 6 months and they work wonderfully. I have to add that my old fan got stuck in the on position, so the electric fans made a performance diff since it spun with up to 7000rpm where it is supposed to start slipping at about 2500-3000rpm.

I have seen a few of these fans mods with the switch in the thermostat housing and its a fuckup.
How can you possibly control the engine temp when you are using the COLD water from the radiatior to switch the fans?
If you are switching at 91deg on the cold side how hot is the inlet into the radiator?
Yes I know that BMW's switch on the cold side but that is because they only want to use the electric fan when the viscous is not coping

the viscous fan shouldn't be running continuously. it is connected to a viscous coupling. the material that fills the coupling gets more viscous the hotter it gets. so the temperature under the bonnet controls the amount that the fans turns. its basically a clutch!!! one that engages more the hotter the engine gets.

I beg to differ about this complicated explanation.I have heard this theory before but in 25 years in the motor industry and I have NEVER seen a viscous bhave in this manner.

A viscous coupling can transmit a certain amount of force before the silicone paste "shears".
This allows the fan to turn when the car is driving slowly but lets it slip at hway speeds when it is not required.

If you rev the engine up slowly you will see and hear the fan start slowing down at about 2500 to 3000 rpm.

i agree with cal... all you have to do is make sure your temp senser on the intake side of the radiator.

interesting stuff, but then at what RPMs can I stick my fingers into it?

or is it the difference between the engine power and the force of the incoming wind at speed battling it out?

still seems like a loss of power to me... 😕 maybe we just shouldn't drive slowly and take the fan out completely 😈
what about using an oil temp sensor instead?

hmmm...

@ calibrator... i guess that my experience in the IT business obviously counts for shit-all then!😉

i am obviously also taking from experiences that i've had in the motor industry, and i was trying to repeat an explanation that i got from an established mechanic once.

i also did a quick search on Wiki, and i got a response exactly like the one i tried to explain:

Wikipedia wrote:

A fan clutch is an automatic device frequently used in automotive cooling systems. When the engine is cool or even at normal operating temperature, the fan clutch partially disengages the engine's mechanically-driven radiator cooling fan, generally located at the front of the water pump and driven by a belt and pulley connected to the engine's crankshaft. This saves power since the engine does not have to fully drive the fan.

However, if engine temperature climbs beyond the clutch's pre-determined setting, the fan becomes fully engaged, thus maintaining or lowering engine temperature.

Most fan clutches are viscous or "fluid" couplings combined with a bi-metallic sensory system similar to that in a thermostat.

regardless - here is where i am coming from:

1. you're right about the fluid in the coupling being silicone. and one property of THAT silicone is that the hotter it gets the more solid it becomes. in fact, it gets very close to being a near complete solid. so it makes sense that when the silicone between the coupling's plates is cold, the plates slip over each other. when it gets hotter, the silicone basically glues those plates together as it gets closer to becoming a solid.

2. it was a mercedes benz, if i am not mistaken, that i was describing. that was the car where the fan was barely spinning while things were cold. at that stage you could stop the blades with you hands and the engine would carry on idling. in fact, the fan would barely spin even if you revved the engine. but the hotter the engine got, the faster the blades would spin. so unless it was some drug that someone had slipped into my drink, that is what i experienced. but perhaps the germans do things differently to the japs.

3. i had never actually thought that deeply about the direction of flow of the water, but now that you mention it - it makes sense (i guess) to switch on the fans based on the temperature of the hot side. it also makes sense that the radiator fills from the bottom and runs towards the engine from the top. however...

4. i have never had any problems with the running temperatures of my ca18det. NEVER. so i wouldnt go as far as calling it a FUCKUP. my engine used to run at halfway on the stock temp gauge. which is what is recommended by the FSM. since i removed the aircon system it now runs ever so slightly below that halfway line??? go figure!!! i hope thats not to much of a fuckup either.

5. i would assume that when the water temperature switch turns the fans on, that the water flowing into the engine would be about 91 degrees celcius. i assume this because i hope that the thermostat is working properly, and at that temperature would therefore be open about 10 degrees prior to this. my assumption leads me to believe that the engine is operating at roughly the right temperature, which i believe to be about 100 degrees. i hope that is right, because i'm not about to go to my garage to get out my FSM now!

6. lastly, even on the drift track, my stock water temp needle stays just below the half mark. the water temp guessometer i have installed barely ever reads over 100 degrees. but dont forget thats on the cold side!

1st fact
You have heard one explanation and seen one car. I have seen hundreds all doing the same thing maybe that should count for something.

I have heard these rumours of locking viscous units but I have yet to see one and it makes absolutely no sense at all as I will explain. You must realise that there are various kinds of silicone pastes some slip as in a viscous fan drive and some lock with heat as in a LSD. You will also find that when a viscous is tired it doesnt transmit drive so you will get the effect that the fan is not turning very well.

After working for 15 years in dealerships I would well advise you to ignore what most mechanics tell you of a cars functioning.

Now if you would take the trouble to step up a car with a functioning viscous you will more than likely see exactly what I have described.

Why have cars been equipped with electric fans? To remove a power sucking device from the engine ie: a permanently engaged fan.

Why do cars have viscous fan drives? To allow the engine to be cooled at low engine speed which more than likely coincides with low road speed. As engine speed rises so does road speed and so does the power required to drive the fan. Hence the need to disengage the fan.

You will also find that most of the vehicles that have a viscous drive unit also have a electric fan as a backup and for use when the aircon is engaged.
Now a simple test
Start a car with a viscous fan.
Rev it up gradually and watch the fan it will start slowing down at some point.
Now get the car up to operating temperature and do the same test and you will observe the same thing.
Now switch the car off hold the fan with your hand or something and start
the car. The fan will attempt to turn but will happily stand still while the engine is running.

End of discussion untill you can produce a car and prove me wrong in which case I will admit I have seen something new.

i dont consider it the end of discussion if you say it is?

also, i mentioned one car that i had seen behave this way. and you just assume that its the only one i've ever seen.

i would love to find the car that behaved that way, but the chances are unlikely and we both know it.

but let me get this right:

you think a viscous fan should be running fully at low engine speeds?
you think a viscous fan should begin disengaging as the speed of the engine increases?

that correct?

this discussion led me to do more research, and everything i've found so far is nicely summarised by this little article:

The thermal viscous fan drive is a silicone-fluid-filled coupling used to connect the fan blades to the water pump shaft. The coupling allows the fan to be driven in a normal manner. This is done at low engine speeds while limiting the top speed of the fan to a predetermined maximum level at higher engine speeds.

A thermostatic bimetallic spring coil is located on the front face of the viscous fan drive unit. This spring coil reacts to the temperature of the radiator discharge air. It engages the viscous fan drive for higher fan speed if the air temperature from the radiator rises above a certain point. Until additional engine cooling is necessary, the fan will remain at a reduced rpm regardless of engine speed.

Only when sufficient heat is present, will the viscous fan drive engage. This is when the air flowing through the radiator core causes a reaction to the bimetallic coil. It then increases fan speed to provide the necessary additional engine cooling.

Once the engine has cooled, the radiator discharge temperature will drop. The bimetallic coil again reacts and the fan speed is reduced to the previous disengaged speed.

so there are obviously different designs out there. i dont remember seeing the little bimetallic coil, but then i dont always pay so much attention to detail. and i was wrong in saying that it depends on engine temperature. it seems fan operation is related to radiator discharge air temperature!

compared to the car i mentioned seeing - that car was cold when the fan wasnt engaging at all. perhaps it wasnt working properly. i dont know.
when it got hotter the fan speed at idle was significantly higher.

dude, without trying to offend you at all, is there a particular reason you're so aggressive when it comes to your own opinions???

Damn, to much to read. If you are looking for a decent electric fan, get the BMW Aircon fan, its from a 5 series, not sure what exact model, its a 2 stage fan, first same as regular fan and second, very strong. If I remember correctly, its a sucking fan.