That explains why when I 1st start my car in the morning the fan runs for about 30 seconds & then disengages. Obviously the fluid has been trapped & has to flow back to the reservoir 1st.
Based on this video: ua-cam.com/video/N_GkuTgJr3w/v-deo.html Looks like the bimetal plate links to a piece of sheet metal that acts like a piston to suck the fluid back in. OR what I was thinking - the drive side has a specific geometry that acts as a pump all the time. so that's two possible solutions.
@@ddjohnson9717 The fins in the clutch act as a pump overcoming the centrifugal force - pumping the oil back. The bimetal thermostat is opening and closing the oil entering the clutch and gets pumped back from turning. If it gets warm enough it opens for the oil and engages the clutch and keeps it engaged until the valve is closed and the oil is pumped back into the reservoir.
@@MrKnutriis yeah so like what i though: drive side has a specific geometry that can pump oil back. The fan side will have drag, and when the valve is open oil stats flow back. Very hard balancing act it looks like. Thanks for clearing up!
The narrator tells us that as long as the valve is open there is a continuous circular flow from the reservoir to the outer body and back to the reservoir. Once the valve is closed the circular flow stops and the reservoir is filled up and the outer parts are emptied. It's all driven by the centripetal force from the rotating parts.
Basically, once the central valve is shut, and the remaining fluid is spun to the outer, a smaller diameter pipe runs from the outer, back to the tank on a slight angle.The remaining air is spun out replacing the fluid, pushing the remaining fluid back to the tank, not all is sent back, some remains but not enough to drive the fan.Hope this helps.
@@nssherlock4547 I said the same thing just without adding things that aren’t there. I can tell you really don’t actually know but not everyone needs to that’s why we all know different things others don’t know. I know exactly how it works I’ve been doing this for 37 years. They also use the same principle for all wheel and 4 wheel drive within the transfer case. As the clutch assembly rotates it has no choice but to spin the fluid from the center outward and that’s what pumps it back into the center it has nowhere else to go
This technology is actually quite genius. I replace my electric fan because there were too many problems with one of these clutches and it has not failed me once so far
I actually did the reverse as my fan clutch failed lol. Initially didn’t set out to remove the serpentine belt-driven fan but after replacing the water pump, radiator, hoses… and not bothering to put the mechanical fan back on, I noticed a 40+ miles increase when running without a fan. At first I thought this is impossible, a 10% increase in MPG just by removing a 15lbs fan?? I kept driving for almost a year without a fan and consistently got at least 40 more miles per tank which has a 400 mile range, sometimes as high as 45 additional miles. Now that it’s summer in TX and I can no longer drive without a fan without the motor running very hot borderline overheat, I ended up putting in a dual electric SPAL fan setup. I was a lot of work because you have to make custom mounting brackets and run wiring.. but it gets better gas mileage and is kinda cool to have an older truck with e-fans.
Ok, so I understand all of that except one thing. How the hell does centrifical force manage to pump the fluid back to the centre? shouldn't it just fling it out to the outside and keep it there?
Shear plate works as impeller of a pump. Shear plate's rotation is a bit faster then its housing, so it causes fluid to flow following plate's rotation. There is a small plastic part inside the housing next to(after) return hole, obstructing the flow. As flow is blocked by the plastic part, its pressure rises and fluid goes through the return hole.
I just found that only some fan clutches have the plastic part. Others without the part seem to using fluid's viscosity itself for making the pressure.
fargeeks I figured out how the fluid returns. The fan always spins slower than the hub, so the centrifugal force is less hence the pressure on the fan side is less so the higher pressure on the hub side pushes the fluid back to the center. Not well explained in the video.
I knew that it had its own fluid that self contained but I never understood the principles in which it acts. Very simple system. No wonder fan clutches last for years before needed to be changed. Still going to convert my Tahoe to electric fans but now I understand how the mechanical clutch works. Thank you for this. Very informative.
I guess I have a seized fan clutch in my truck, sounds like a huge vacuum, "windy", I was gonna try to oil n shimmy the coil get it loose if possible make it last more but na , 23 years working Is enough, it's time to change it
Also worth mentioning these things last forever. Ive rebuilt several engines in vehicles from the 70s 80s with over 150k miles. Have not once replaced the fan clutch
Had one fail recently on my 2005 Ram 5.7. The problem presented as a high pitched whistle of all things, when the fan was supposed to engage. Took months to figure out after replacing the EGR, PCV, water pump, with no luck. Replaced the fan clutch with the water pump (and the radiator after nicking it.. oops) and voila! Noise gone and I can clearly hear the fan engage and disengage. It's actually a pleasure to hear the fan come on and off as it's a more aggressive pitch die to tow package. Also, the truck roars for a second when I start it as the fan spins before it disengages.
3:15 how does the fluid get pumped back into the reservoir? I don't get it...I would have thought that the centrifugal forces are so high, that the fluid only comes back into the reservoir, when you switch off the engine?
Anyone with an 05 Aviator. If your car roars and revs high all the time change your fan clutch because it’s stuck. Four Seasons makes a great one that will give you some extra mpg.
I just drill holes in the clutch, run a tap and then insert some bolts. When you live in the desert Southwest it seems okay to have the fan on all the time after it breaks anyway.
I cut even pieces from the fan blades when i did that because the fan would run at a higher speed and take too much power. Still sounds loud. I might cut off of a bit more.
@@aminecatalyseur8281 the fan clutch is sealed, no way to change the fluid inside. my original fan is still working good and it has 190k miles. a new one is cheap, it's best to buy a new one if yours goes bad
That explains why my friend twisted that piece the spring is connected to.. the fan quit working so he twisted that part and now it’s always working lol.. i know he’s coming up my street because i can hear the fan going from 2 blocks away
The Humvee has a hydraulic activated fan. An extra hydraulic line comes from the power steering pump and goes to a solenoid. When the solenoid opens the hydraulic fluid pressure flows to the fan clutch and engages the clutch. It's really interesting and pretty simple.
My 1989 toyota celsior had the power steering fluid driven fan too. It worked well, 46°c outside, both air conditioners on, temperature remained optimal
Not so accurate description of the functionality... Centrifugal force alone can not return the viscous fluid back to center located reservoir. And viscous clutch never works on full engagement it has always to slip even with "fully engaged" (=> 95% of input speed). Rotational speed difference is actually the "pumping force" making the viscous fluid return back to reservoir. And it can never fully disengage too... There will always be some fluid left between those rotational elements creating small amount of drag for the clutch making the blade always spin. So no points for this explanation.
This is a better option than electric option with sensor,especially when is too hot ,often electric sensor can failed and he can't engage the electric motor in the fan,big buses often have that problem,and bus engine could overheat when that happened ,because there is not enough fan cooling power to cool the engine.
hostilityy it can be ,but i didn't have any problems with this kind of cooling system on the buses ,i work in the bus company on maintenance.We had some big troubles with sensors ,they often fail,here in Europe,main producer of the cooling systems and fans is a German company Behr,many trucks and buses have their parts.
I disagree quality electric fans will greatly reduce drag on your engine thus reducing heat and friction and it being it's own independent function from the motor reduces time and money spent working on your vehicle also clutch fans have a sensor it's usually connected close to your thermostat housing.
+Kike Croatia This can fail just like electric fan / sensor. Temperature sensor is extremely simple device, it should not be prone to failure and if it is prone to failure, as a cheap component the car manufacturer could put many of them for redunancy. There probably has been some manufacturing or design error or if a lot of them have been failing at your area. When done properly, it should not fail very easily . . . Indeed this is a good system too. But difficult to say what is better. Electric has some advantages in the way how the ECU can easily control it.
I don’t understand how the oil goes back to the center reservoir when the valve closes centrifugal forces would keep it to the outside and keep the fan engaged even if it has a clear path back ???
They look super technical on the outside but inside they are all cheaply made in China devices. The internal fluid regulation is controlled by a cheaply made piece of galvanized folded tin connected to the spring on the outside.. They try to make out they are this super technical device so they can charge you lots of $$$ to buy them when in reality they are really just smoke and mirrors.They only have between 18mm to 27mm of silicone fluid in them too, any more than that and they stay engaged or locked on.
Thank god an actual video that exspains how they are supose to work I hope ford's have watched this Mr Ford man there not supose to spin when radiator is cold ie engine coolent temp passing through rad and when they roar when cold and spin when cold there goosed I wished all the deisel engineers and garages would have watch this it would have saved me 5 rads and stats and pumps
All of the viscous fluid settles to the bottom of the clutch when it sits overnight. This causes a brief engagement (depending on the outside temperature) before the fluid can work its way back to the center of the clutch and begin to operate normally.
When the engine is cold, should the fan be spinning at all? Should I be able to stop a viscous fan by hand when the engine is cold? I know I shouldn't be able to stop it when it's hot, as the clutch is engaged, but what about when it's cold?
Complicated peace of sh1t ....why simple when it can be complicated ....What is wrong with normal radiator fans ,fixed type like on vintage cars and trucks ?,they worked just fine.
Mercedes diagnosis question. Visco fan clutch is attached to water pump pulley. When motor is shut off and hot, fan should still be engaged and difficult to turn because belt tension is holding water pump pulley. When motor is cold, fan clutch should free wheel with little resistance. Is this correct?
wait I still dont understand, why is when you start your engine cold, the fan spins or engages and blows wind strongly then after 5 minutes or if the engine heats up, it just freely spins then after a few minutes of driving, it engages again and blows so much air?
It could be because when the engine was hot and you switched it of, the hot liquid fell to the bottom of the friction plates because gravity. Then when you start it cold, it's thick and not viscous until it warms up and starts the cycle. What I don't get is I've had new fan clutches on a hot day and a hot engine and you can stop it with a rag and it's just doesn't seem to be doing any thing useful.
Poor design...and even worse is the 1 piece shroud.....could be a 15 minute fix if they engineered it better....a 6 year old could have done a better job
When I have viscose fan clutch go bad I just drill and tap a few holes in it then put in a few bolts to lock it up. It's not going to get much more broke. That will work temporarily till you can get it fixed.
I guess if you lived in a really hot climate, that would make sense. You're gonna lose a lot of power and MPG, tho. They are pretty damn cheap, tho, or they used to be, and changing it might even take less time than your temp fix.
Electric fans do cause additional heat beeing generated by the inverter which needs to provide the power. If you think of a large engine, that's quite significant, since the fan is large. Turning the fan with a clutch is much better.
@@RubenKelevra interesting. Good point now that i think about it. I always thought electric fans for smaller engines are the way to go. That could be why after modernization throughout the years, almost all manufacturers switched to electric instead of clutch based fans like they had back in the day for small engines. I do remember seeing a BMW with a fan clutch, a pretty modern one too. I was quite surprised that it didn't have an electric one for cooling. I suppose there will always be a debate between one or the other.
@@jstkyoshi the reason why manufacturers started to use electric fans is simple: You can run them when the engine is not running. Most cars have start/stop automatics, but in hot climate in stop and go traffic the engine needs constant additional cooling. Additionally you can run the fan after the engine was shut down to make sure it cools down more evenly when it was under high temperature stress. This ensures the longevity of the engine. On trucks on the other hand you barly run into such troubles, since you usually don't park after a long stop and go inside a city. You don't shut off a truck engine in stop and go and you most likely drive around slowly to park it after that. Also diesel engines have much more "meat", so the heat conductivity inside the motor is larger, so they tend to cool down much more evenly.
@@RubenKelevra Seems like the newer air clutches on fans have to work with 30 or 35 h.p. because the fan pulls so much air. They even work with the engine brake in the retarding process so that's why the air operated fan clutch. The computer kicks it on or off..
Seems like a touchy balance between the pumping of the fluid and the centrifugal force. Once it is spinning why would any of the fluid ever make it's way back to the reservoir if it was being held by the centrifugal force? There would have to be an imbalance of pressure between the fluid moving out and the fluid returning. I don't see how that imbalance is achieved.
Nice! Having mostly worked on motorcycles and VWs I was wondering what that spring was for. I was told that the viscous fluid was temp sensitive, activating the drive by thickening to transfer the power (as viscous couplers work in some all wheel drive systems).
Now explain how my fan exploded
😂
HAHAHA!
Well I'll be damned. Always been curious about this and now I know. Thanks a bunch!!
That explains why when I 1st start my car in the morning the fan runs for about 30 seconds & then disengages. Obviously the fluid has been trapped & has to flow back to the reservoir 1st.
Yes - and the oil is very viscous when it is cold so it tends to drag the fan initially.
It all makes sense now lol
@@MrKnutriis Particularly more noticeable on a colder day vs warmer ambient temp day.
Fans not moving on car
Incredible Engineering 👏😮
Impressive engineering for a $25 part.
What kind of car uses a viscous fan clutch that only costs $25? I'm looking at around $400 for one for my 2003 Nissan Patrol.
@@GarySchiltz factory Nissan parts are ridiculous. Last one I bought for my keep was $25 at O'Reilly. Lol
@@GarySchiltz if your still looking to buy one check rockauto they usually have the cheapest prices. I buy all my parts from them
@@GarySchiltz thats ridiculous
@@GarySchiltz I just purchased and installed a brand new water pump and fan clutch assembly on my 1995 Nissan D21 for $48 brand new lol
How does the fluid flow "uphill" or against centrifugal force in the return lines?
Based on this video: ua-cam.com/video/N_GkuTgJr3w/v-deo.html
Looks like the bimetal plate links to a piece of sheet metal that acts like a piston to suck the fluid back in.
OR what I was thinking - the drive side has a specific geometry that acts as a pump all the time. so that's two possible solutions.
@@ddjohnson9717 The fins in the clutch act as a pump overcoming the centrifugal force - pumping the oil back. The bimetal thermostat is opening and closing the oil entering the clutch and gets pumped back from turning. If it gets warm enough it opens for the oil and engages the clutch and keeps it engaged until the valve is closed and the oil is pumped back into the reservoir.
@@MrKnutriis yeah so like what i though: drive side has a specific geometry that can pump oil back. The fan side will have drag, and when the valve is open oil stats flow back. Very hard balancing act it looks like. Thanks for clearing up!
a small valve
@@ddjohnson9717 Well, it's not that difficult
I still wonder, why????? Just why
🔵 I'm still not quite clear on how the fluid is "Pumped" back to the storage-chamber when the temperature drops below the 'On' set point.
The narrator tells us that as long as the valve is open there is a continuous circular flow from the reservoir to the outer body and back to the reservoir. Once the valve is closed the circular flow stops and the reservoir is filled up and the outer parts are emptied. It's all driven by the centripetal force from the rotating parts.
Centrifugal force makes it go from the reservoir in the center outward towards the clutches and creates a drag between them
@@wb3161 And.. now explain what the OP actually asked.
Basically, once the central valve is shut, and the remaining fluid is spun to the outer, a smaller diameter pipe runs from the outer, back to the tank on a slight angle.The remaining air is spun out replacing the fluid, pushing the remaining fluid back to the tank, not all is sent back, some remains but not enough to drive the fan.Hope this helps.
@@nssherlock4547 I said the same thing just without adding things that aren’t there. I can tell you really don’t actually know but not everyone needs to that’s why we all know different things others don’t know. I know exactly how it works I’ve been doing this for 37 years. They also use the same principle for all wheel and 4 wheel drive within the transfer case. As the clutch assembly rotates it has no choice but to spin the fluid from the center outward and that’s what pumps it back into the center it has nowhere else to go
Want to see a vicious fan? Go to the coliseum in Oakland, after the Raiders lose to Seattle!! 😂😂😂😤👻🤯
This technology is actually quite genius. I replace my electric fan because there were too many problems with one of these clutches and it has not failed me once so far
I actually did the reverse as my fan clutch failed lol. Initially didn’t set out to remove the serpentine belt-driven fan but after replacing the water pump, radiator, hoses… and not bothering to put the mechanical fan back on, I noticed a 40+ miles increase when running without a fan. At first I thought this is impossible, a 10% increase in MPG just by removing a 15lbs fan?? I kept driving for almost a year without a fan and consistently got at least 40 more miles per tank which has a 400 mile range, sometimes as high as 45 additional miles.
Now that it’s summer in TX and I can no longer drive without a fan without the motor running very hot borderline overheat, I ended up putting in a dual electric SPAL fan setup. I was a lot of work because you have to make custom mounting brackets and run wiring.. but it gets better gas mileage and is kinda cool to have an older truck with e-fans.
Changed mind 3 time and each time freon is released NO A/C 😢
Ok, so I understand all of that except one thing. How the hell does centrifical force manage to pump the fluid back to the centre? shouldn't it just fling it out to the outside and keep it there?
Shear plate works as impeller of a pump.
Shear plate's rotation is a bit faster then its housing, so it causes fluid to flow following plate's rotation.
There is a small plastic part inside the housing next to(after) return hole, obstructing the flow.
As flow is blocked by the plastic part, its pressure rises and fluid goes through the return hole.
I just found that only some fan clutches have the plastic part.
Others without the part seem to using fluid's viscosity itself for making the pressure.
Kelly Larsen .
Better for you to play with jumping jacks than with machines.
Centrifugal...😎
@@carlosmejia5728 Centripetal. Centrifugal force is imaginary. :p
WARNING WARNING!!!!! DONT OPEN UP AN OLD ONE,THE SMELL WILL MAKE YOU VOMIT
I don’t see how the fluid gets returned against the centrifugal force.
Perhaps so but i can see how these can go bad after years of use
fargeeks I figured out how the fluid returns. The fan always spins slower than the hub, so the centrifugal force is less hence the pressure on the fan side is less so the higher pressure on the hub side pushes the fluid back to the center. Not well explained in the video.
These is the best description of how the fan clutch works. Thanks for explain it.
I knew that it had its own fluid that self contained but I never understood the principles in which it acts. Very simple system. No wonder fan clutches last for years before needed to be changed. Still going to convert my Tahoe to electric fans but now I understand how the mechanical clutch works. Thank you for this. Very informative.
I guess I have a seized fan clutch in my truck, sounds like a huge vacuum, "windy", I was gonna try to oil n shimmy the coil get it loose if possible make it last more but na , 23 years working Is enough, it's time to change it
Also worth mentioning these things last forever. Ive rebuilt several engines in vehicles from the 70s 80s with over 150k miles. Have not once replaced the fan clutch
*Sprinter owners look over suspiciously*
Had one fail recently on my 2005 Ram 5.7. The problem presented as a high pitched whistle of all things, when the fan was supposed to engage. Took months to figure out after replacing the EGR, PCV, water pump, with no luck. Replaced the fan clutch with the water pump (and the radiator after nicking it.. oops) and voila! Noise gone and I can clearly hear the fan engage and disengage. It's actually a pleasure to hear the fan come on and off as it's a more aggressive pitch die to tow package. Also, the truck roars for a second when I start it as the fan spins before it disengages.
3:15 how does the fluid get pumped back into the reservoir? I don't get it...I would have thought that the centrifugal forces are so high, that the fluid only comes back into the reservoir, when you switch off the engine?
Works almost like a torque converter!
Yeah.. almost..
No!
@@ghenkhoash2440 Tell us the difference Ghen
@@ethics3 Torque converter uses fluid kinetic to transfer power, But this one uses fluid viscosity.
@@ghenkhoash2440 elaborate please
Anyone with an 05 Aviator. If your car roars and revs high all the time change your fan clutch because it’s stuck. Four Seasons makes a great one that will give you some extra mpg.
It works the same way as anything else vicious. It gets angry and bites.
I just drill holes in the clutch, run a tap and then insert some bolts. When you live in the desert Southwest it seems okay to have the fan on all the time after it breaks anyway.
Mine had gone bad and I just epoxied it in place until I could replace it.
I cut even pieces from the fan blades when i did that because the fan would run at a higher speed and take too much power. Still sounds loud. I might cut off of a bit more.
@@nairdacharles9492 Yes, or even better; replace the clutch. It's a $25 - 5 minute job - or 25 minutes if you're really slow.
true until you use the highway.
I've always wondered how the viscous fan clutch on my E39 worked, this video was quick and made it simple to understand, thanks!
I want to change this oil to make it strong did u try it i have 525 tds e39
@@aminecatalyseur8281 the fan clutch is sealed, no way to change the fluid inside. my original fan is still working good and it has 190k miles. a new one is cheap, it's best to buy a new one if yours goes bad
@@busterscrugs really thank u so much..
e39 owner here also lol
Your BMW can drive just fine without the fan as long your electric fan for the radiator works.
One of the more amazing overlooked parts.
Perfectly explained. Thank you.
WOW, I learned something new today, THANK YOU !!!!
Interesting! I used to think it was just a plate being pushed closer to another plate and always filled with thick oil.
"bi-metallic strip" Technology Connections has entered the chat
I removed the clutch fan. And install electric fan. No more belt slip.
How much did it cost$$??? I own a Sierra 1500 with clutch fan n don't like it at all.
That explains why my friend twisted that piece the spring is connected to.. the fan quit working so he twisted that part and now it’s always working lol.. i know he’s coming up my street because i can hear the fan going from 2 blocks away
The Humvee has a hydraulic activated fan. An extra hydraulic line comes from the power steering pump and goes to a solenoid. When the solenoid opens the hydraulic fluid pressure flows to the fan clutch and engages the clutch. It's really interesting and pretty simple.
Salty Steel some Toyota’s had that too. Hydraulic fans are cool tech.
@George Vinson I can imagine. It’s a complex system.
@@TheShamiester Yeah, I think some early '90 Camrys with the V6 had them.
@@glennfrancis9031 I know the ones we got from Japan had them as well on the diesel version.
My 1989 toyota celsior had the power steering fluid driven fan too. It worked well, 46°c outside, both air conditioners on, temperature remained optimal
Not so accurate description of the functionality... Centrifugal force alone can not return the viscous fluid back to center located reservoir. And viscous clutch never works on full engagement it has always to slip even with "fully engaged" (=> 95% of input speed). Rotational speed difference is actually the "pumping force" making the viscous fluid return back to reservoir. And it can never fully disengage too... There will always be some fluid left between those rotational elements creating small amount of drag for the clutch making the blade always spin. So no points for this explanation.
This is a better option than electric option with sensor,especially when is too hot ,often electric sensor can failed and he can't engage the electric motor in the fan,big buses often have that problem,and bus engine could overheat when that happened ,because there is not enough fan cooling power to cool the engine.
Wrong. this junk can fail too.
they've been replaced by modern electric fans with separate sensors because of more reliability.
hostilityy it can be ,but i didn't have any problems with this kind of cooling system on the buses ,i work in the bus company on maintenance.We had some big troubles with sensors ,they often fail,here in Europe,main producer of the cooling systems and fans is a German company Behr,many trucks and buses have their parts.
Daver G very smart,but you must connect that switch by relay,because that fan need a lot of current.
I disagree quality electric fans will greatly reduce drag on your engine thus reducing heat and friction and it being it's own independent function from the motor reduces time and money spent working on your vehicle also clutch fans have a sensor it's usually connected close to your thermostat housing.
+Kike Croatia This can fail just like electric fan / sensor. Temperature sensor is extremely simple device, it should not be prone to failure and if it is prone to failure, as a cheap component the car manufacturer could put many of them for redunancy. There probably has been some manufacturing or design error or if a lot of them have been failing at your area. When done properly, it should not fail very easily . . .
Indeed this is a good system too. But difficult to say what is better. Electric has some advantages in the way how the ECU can easily control it.
I don’t understand how the oil goes back to the center reservoir when the valve closes centrifugal forces would keep it to the outside and keep the fan engaged even if it has a clear path back ???
🔵 Yeah!.... how exactly is that made to happen?....I was wondering that myself!
They look super technical on the outside but inside they are all cheaply made in China devices. The internal fluid regulation is controlled by a cheaply made piece of galvanized folded tin connected to the spring on the outside.. They try to make out they are this super technical device so they can charge you lots of $$$ to buy them when in reality they are really just smoke and mirrors.They only have between 18mm to 27mm of silicone fluid in them too, any more than that and they stay engaged or locked on.
Or just have an electric motor driven fan and a temp sensor done
The exact point of this clutch is to avoid what you suggested.
Many thanks for such a great demonstration ...
Why even have a fan clutch? I doubt my 1970 RR has a fan clutch!!!
Thank god an actual video that exspains how they are supose to work I hope ford's have watched this Mr Ford man there not supose to spin when radiator is cold ie engine coolent temp passing through rad and when they roar when cold and spin when cold there goosed I wished all the deisel engineers and garages would have watch this it would have saved me 5 rads and stats and pumps
Thank you. Clear and to the point. Nice job.
So when i start my van in the morning. It's like the clutch fan is in-ganged for a minute. Then it's normal.. Why's this??
All of the viscous fluid settles to the bottom of the clutch when it sits overnight. This causes a brief engagement (depending on the outside temperature) before the fluid can work its way back to the center of the clutch and begin to operate normally.
@@KitMastersInc very helpful.. thank you.
Ah that's good !! I ready change my fun clutch 😊 now it's work great!
When the engine is cold, should the fan be spinning at all? Should I be able to stop a viscous fan by hand when the engine is cold? I know I shouldn't be able to stop it when it's hot, as the clutch is engaged, but what about when it's cold?
Extremely useful, thanks sir.
harmonics ?? I was taught keep it fluid my whole town is gelled up
That's a very comprehensive explanation, simply put yet well said.
Complicated peace of sh1t ....why simple when it can be complicated ....What is wrong with normal radiator fans ,fixed type like on vintage cars and trucks ?,they worked just fine.
How did the UA-cam know exactly what I want to know?
Just in process of change fan clutch on 2011 Dakota. Question does cold temp affect the clutch fluid? This morning the outside temp is -20C.
Mercedes diagnosis question. Visco fan clutch is attached to water pump pulley. When motor is shut off and hot, fan should still be engaged and difficult to turn because belt tension is holding water pump pulley. When motor is cold, fan clutch should free wheel with little resistance. Is this correct?
wait I still dont understand, why is when you start your engine cold, the fan spins or engages and blows wind strongly then after 5 minutes or if the engine heats up, it just freely spins then after a few minutes of driving, it engages again and blows so much air?
It could be because when the engine was hot and you switched it of, the hot liquid fell to the bottom of the friction plates because gravity. Then when you start it cold, it's thick and not viscous until it warms up and starts the cycle. What I don't get is I've had new fan clutches on a hot day and a hot engine and you can stop it with a rag and it's just doesn't seem to be doing any thing useful.
Poor design...and even worse is the 1 piece shroud.....could be a 15 minute fix if they engineered it better....a 6 year old could have done a better job
How does the fluid return to the center housing when the entirety is spinning?
I have a 96 Tacoma with 300k miles and the engine fan runs all the time, even when it is 20 below zero.
The return part of the fluid is what does not understand. The centrifugal force works on the return fluid too, so where is the "pumping" efect??
Why not a direct drive ? Because in low rpm not enough Flow ?
No explanation of why this design is used, or what it's initial reason was for. Why did we change from the fixed blade fan ?
Well the fan on my car runs every time.......does this mean , there is a malfunction? 😅
So that is why my shit (03 dodge durango rt) is so loud when i 'm not hauling ass Or when i am hauling ass. Damn!!!
That was very well explained.
When I have viscose fan clutch go bad I just drill and tap a few holes in it then put in a few bolts to lock it up. It's not going to get much more broke. That will work temporarily till you can get it fixed.
Shawn Travels The World I have did the same thing. It sounds like an airplane under the hood though
I guess if you lived in a really hot climate, that would make sense. You're gonna lose a lot of power and MPG, tho. They are pretty damn cheap, tho, or they used to be, and changing it might even take less time than your temp fix.
@@l337pwnage cool story bro.
Answer to the question, How does a viscous fan clutch work? They don't.
What's going on if the fan its always engaged?. Even if the engine it's turned off it's tight to move by hand.
the fan is faulty and needs to be replaced. it should spin freely by hand if the engine room/ambient temp is cold
In my experience most of them don't work that great. Better to have electric fans
For big heavy duty diesel engines, fan clutches i find work best for me. Small engines, i'd say electric fans are a better option.
Electric fans do cause additional heat beeing generated by the inverter which needs to provide the power. If you think of a large engine, that's quite significant, since the fan is large. Turning the fan with a clutch is much better.
@@RubenKelevra interesting. Good point now that i think about it. I always thought electric fans for smaller engines are the way to go. That could be why after modernization throughout the years, almost all manufacturers switched to electric instead of clutch based fans like they had back in the day for small engines. I do remember seeing a BMW with a fan clutch, a pretty modern one too. I was quite surprised that it didn't have an electric one for cooling. I suppose there will always be a debate between one or the other.
@@jstkyoshi the reason why manufacturers started to use electric fans is simple: You can run them when the engine is not running. Most cars have start/stop automatics, but in hot climate in stop and go traffic the engine needs constant additional cooling. Additionally you can run the fan after the engine was shut down to make sure it cools down more evenly when it was under high temperature stress. This ensures the longevity of the engine.
On trucks on the other hand you barly run into such troubles, since you usually don't park after a long stop and go inside a city. You don't shut off a truck engine in stop and go and you most likely drive around slowly to park it after that. Also diesel engines have much more "meat", so the heat conductivity inside the motor is larger, so they tend to cool down much more evenly.
@@RubenKelevra Seems like the newer air clutches on fans have to work with 30 or 35 h.p. because the fan pulls so much air. They even work with the engine brake in the retarding process so that's why the air operated fan clutch. The computer kicks it on or off..
No wonder why engine fans have chunky metal centers everytime is work around engines...
What is wrong with simply an electric fan? Why all these mechanical stuff that is prone to fail over time.
How many ml do we need to replace the silicone oil thanks
Growing up, I heard the term viscous used for the fan clutch. Being young, I thought it was vicious and I thought why would a fan be that?
Stick your hand in it and find out.
This clutch fan is additional money making of car manufacturer
Sorry I am challenging to understand this animation video need slow and long mean no cut separate each.
So fan clutch without cord cheaper then corded fan clutch 🤷🏻♂️
Seems like a touchy balance between the pumping of the fluid and the centrifugal force.
Once it is spinning why would any of the fluid ever make it's way back to the reservoir if it was being held by the centrifugal force?
There would have to be an imbalance of pressure between the fluid moving out and the fluid returning. I don't see how that imbalance is achieved.
🔵 Yeah,... I'm havin' a bit of a problem wrap'n my head around that-one to!
He explains that. The thin fins cause pumping action that overcomes the centrifugal force, forcing the liquid back to the center.
What direction does the bimetallic spring in the center turn when its hot?
never had any trouble with type of clutch but really got into a crimp with a newer air operated one. Good explanation and Thanks!
Can i run a bolt thru and lok them up ? Like we did in the 70s and 80s
Ok sir
🎉 Thankx for sharing. I need one that I am sure of.😢
I wonder why after 3 different new ones they stay engaged on a 04 Ram
This guy read text - not professionally.
Fan works freely when engine is running hot ????
Thank you so much, this gave me all the info I could have hoped for!
I had no idea this was a thing. I thought the fan somehow just had some resistance and soun willy nilly with the crank
There are ones that are just friction based and not temperature controlled. Those don't have a spring temp sensor on them.
Can you stop Viscous fan's when the fan clutch is engaged or will you injure your hand?
What temp would the clutch engage on a gm truck?
Do you need replace/add the fluid regularly?
Should a cold fan/engine free spin? Should a cold engine fan still spin on start up?
It will a little bit just because it is still on a rotating assembly.. there is some drag to the fan even when not engaged.
So then a simplified version could be made like the tesla turbine with a oil? since the turbine behaves in the same manner
I don’t understand why such a thing is needed.
The deadpan teleprompter read is unsettling.
Great Video!
Hey!!
Greetings from Colombia 🇨🇴 South America!!
Nice video and l explanation !!
Thanks
What will those eggheads think of next.
Is nothing simple nowadays?
I just replaced mine in my 2004 Suzuki Grand Vitara, it finally stopped working after 16 years and almost 200 thousand kilometers.
Mate, this is one of the best educational videos I have seen. Well done, animations were amazing!
Fucking bi- metallic strips
Very cool, Big Fan.
Every single Toyota truck / body on frame SUV is fitted with these clutches, making that signature whoosh even in 2022.
Nice! Having mostly worked on motorcycles and VWs I was wondering what that spring was for. I was told that the viscous fluid was temp sensitive, activating the drive by thickening to transfer the power (as viscous couplers work in some all wheel drive systems).
So kind of like a torque converter?
Part 2 what causes them to fail????