Fan Clutches and how they really work

[ShaggyRV]

Hello all:

I have had problems with my Granville running hotter than normal since purchase. Here is my story.

The RV would get up pretty high near the top mark below the red on the highway or climbing hills. I was ready to head to Key West back in August so I went down to Autozone and picked up a Fan Clutch. Took off on my trip with no real improvement. When I got home I put in a new Radiator, Thermostat, Water Pump, belts and hoses. I take her out for a spin and same problem. I start reading up on Fan clutches online and everybody says fan clutch would not cause it to run hot on the highway, Blah Blah Blah. So I put the original Aisin Fan clutch back in and it runs cool down the highway, Up hills etc. The only problem was it was howling all the time. fully engaged which was eating up power and MPG. Well I finally ordred a new Aisin brand replacement and all is well. Its a little cold out now but even at 45 deg with the autozone clutch it would almost overheat climbing some of the small mountains here in eastern WV. The new one is working great!! So my advice is to only buy an OE type as its hit and miss with the aftermarket crap. i've seen where some guys have gone through 3 before they get a good one. Some folks replace theirs and then say well thats not the problem so they refuse to believe they might have got a bad one so they head down the road of wasting tons of money replacing everything else. for me I planned to replace all the other stuff anyhow so no harm no foul. I am attaching a link to an interesting link that talks about how our fan clutches work including instructions on how to refill/calibrate them. Enjoy!!!

http://neuralfibre.com/paul/4wd/tuning-and-understanding-your-toyota-viscous-fan-clutch

[Riverman77]

You are spot-on about these fan clutches, ShaggyRV!

Ever since I had the fan clutch installed at a repair shop (using whatever brand X they used), I have never been satisfied with the high temps that I run. I have a 1988 Dolphin with a 22RE. When climbing the mountain passes, I manually put the shifter into 2nd and don't exceed 45 mph. By the time I hit the top of the passes, I'm usually gritting my teeth because the temp guage is dangerously close to the upper line. Before my next trip, I will have been to Toyota and get the correct OEM fan clutch.

Thanks for the reminder of that little, overlooked item in the cooling department and the "cool link" that you had included!

P.S. Has anyone ever used "Water Wetter" additive to add to the anti-freeze? It is supposed to cool the system up to some big (?) % more.

-Riverman77

[ShaggyRV]

You are spot-on about these fan clutches, ShaggyRV!

Ever since I had the fan clutch installed at a repair shop (using whatever brand X they used), I have never been satisfied with the high temps that I run. I have a 1988 Dolphin with a 22RE. When climbing the mountain passes, I manually put the shifter into 2nd and don't exceed 45 mph. By the time I hit the top of the passes, I'm usually gritting my teeth because the temp guage is dangerously close to the upper line. Before my next trip, I will have been to Toyota and get the correct OEM fan clutch.

Thanks for the reminder of that little, overlooked item in the cooling department and the "cool link" that you had included!

P.S. Has anyone ever used "Water Wetter" additive to add to the anti-freeze? It is supposed to cool the system up to some big (?) % more.

-Riverman77

The aisin fan clutches are available online. You don't have to go to Toyota. They are also quite easy to change if you choose. I'm sure Toyota is going to overcharge you. I got mine from carpartsdiscount.com $56 plus $16 shipping. I'm sure you can get one a little cheaper if you look around. I'm sure you can get it installed someplace cheaper or do it yourself its just 4 bolts that hold it on the water pump shaft. There are 4 bolts that hold the fan to the clutch once you get it out. good luck and I think it will solve you problem. I have known some who used water wetter. No real help from what I've heard. Try a new fan clutch and I think you'll be happy.

[zero]

everybody says fan clutch would not cause it to run hot on the highway, Blah Blah Blah.

I now that not "everybody" says that. Most factory engineered cars and trucks need no fan at highway speeds when air temps are 90 F or lower and the AC is not being used. A Toyota minitruck with a motorhome body on it is NOT engineered by Toyota and is fairly overloaded and underpowered all the time.

I've pulled 10,000 lb. trailers with my pickup during the summer and the fan never comes on unless I'm climbing a long hill or stopped at a red light. My viscous driven fan is huge and it sounds like a small helicopter when it engages.

A viscous drive fan clutch is simply a temp sensitive torque converter. Should be spinning your fan at 80% engine speed when coolant temp is over 200 degrees F. Pretty easy to check on some trucks and not so easy on others.

As to bad parts? Many parts sold by part jockeys like Autozone, Advance, NAPA, etc. are generic and often not specifically targeted for just one vehicle. That being said - you bought only one Aisin clutch and it worked well - correct? That is not exactly proof that all Aisin clutches are good and all others are bad.

Yeah, I know - now I'm guilty of what you call "blah,blah, blah.,"

Did you ever stick any of your non-working fans in a pot of hot water and check for lock up and at what temp? It would be interesting to see what was actually different between the Auto-Zone supplied clutches and the Aisin you bought.

[waiter]

Shaggy, Good info. I get the whining on mine also, not all the time, but it seems like its runs when it probably doesn't need to.

I've been considering going electric. (I change my mind every time I get ready to order the stuff)

JOhn Mc

88 Dolphin 4 Auto

[Totem]

I can't wait to see someone in this forum go electric. Posting on their following motor replacement thread will be thoroughly enjoyable told ya so moment for me.

[waiter]

....Posting on their following motor replacement thread....

Totem, thats why I change my mind back every time I decide to do it. :-(

John Mc

88 Dolphin 4 Auto

[Derek up North]

So what's the big 'problem' with electric fans. It seems to me that 100% of new cars on the road manage just fine without requiring frequent 'motor replacement'.

[waiter]

I don't think it would be a problem, Its a matter of taking something that is known to work (maybe not exactly the way I like) and try something that is unknown. Thats why its not real high on my list of things to do.

However, everytime it 20 degrees outside, and I hear the mechanical fan kick in, I say to myself, I wonder if an electric fan would do a better job.

Then in the summer when its 95 outside and the mechanical fan is running, I say to myself, I wonder if an electric would be able to keep the engine cool.

This might be the year to try electric, maybe. :-)

JOhn Mc

88 Dolphin 4 Auto

[Totem]

The problem is your application. As I have mentioned before, you will NOT get the cooling capacity and airflow needed for your application ( a hot as heck overworked underpaid engine ) with an electric fan powered by a crummy 60 amp alt. tell me how many semis, large engine trucks etc are using electric... Now in a light duty application with much larger alternator you can. But at that point the alternator is your engine leech instead of the fan drive. Take your poison whichever way you want; but there is one final thing to remember. Airflow resistance at high speed will require some muscle... And electric motors need a lot of juice to make the same kind of muscle. And what brain will be driving that in a non OBD ii truck? So now you will need a controller and interface for the larger alternators output to govern fan speed, unless of course you just want it to run continuously...

[Totem]

And to waiters comment, your fan kicking in when its 20 degrees outside means its hot enough inside the engine bay to trip the bimetallic thermostat on the fan drive...i'm janitor here....

[zero]

The problem is your application. As I have mentioned before, you will NOT get the cooling capacity and airflow needed for your application ( a hot as heck overworked underpaid engine ) with an electric fan powered by a crummy 60 amp alt. tell me how many semis, large engine trucks etc are using electric... Now in a light duty application with much larger alternator you can. But at that point the alternator is your engine leech instead of the fan drive. Take your poison whichever way you want; but there is one final thing to remember. Airflow resistance at high speed will require some muscle... And electric motors need a lot of juice to make the same kind of muscle. And what brain will be driving that in a non OBD ii truck? So now you will need a controller and interface for the larger alternators output to govern fan speed, unless of course you just want it to run continuously...

I agree 100%. A Toyota 18'-21' RV is underpowered and overloaded. Might even have decreased passive air-flow through the engine bay (not sure about that). I doubt any cost-effective electric fan is adequate. I've got four HD diesel pickups set up for towing and all have very large mechanical fans controlled by viscous cluthes. The new 2013 HD pickups are still using mechanical fans and I suppose there is good reason for it.

[zero]

So what's the big 'problem' with electric fans. It seems to me that 100% of new cars on the road manage just fine without requiring frequent 'motor replacement'.

Where I live most of the electric fan failures I've seen are from road-salt damage. A problem that does not exist in much of the country, I assume. NY and Michigan use road salt summer and winter in some areas. Every electric fan I've had to replace had bad/dried out bearings.

Not an issue on trucks made to work hard since all I've see have mechanical fans and not electric.

[Totem]

If they didn't I would be unemployed. I challenge Mr. Dereck to go electric though. Please post pics and keep us informed of the controller you use,alternator etc. of course, post the costs and finally when you still overheat, post the engine replacement thread, or the tow thread. We will be waiting...:-)

[Derek up North]

What's your coolant temperature gauge showing when it's 20F outside and the fan's running?

However, every time it 20 degrees outside, and I hear the mechanical fan kick in, I say to myself, I wonder if an electric fan would do a better job.

[zero]

There are add-on aftermarket kit to up electric fans on trucks. Around 6000 CFM and they draw near 40 amps with a 12 volt system.

Here's one if somebody really wants it for their Toyota. Better upgrade to a 120 amp alternator though!

http://klmperformance.com/flex-a-lite/flex-a-lite-ford-diesel-truck-fans.html

[waiter]

What's your coolant temperature gauge showing when it's 20F outside and the fan's running?

Its hanging around 1/3. I've never had any problems with cooling. I'll see it creep up a little on a hard climb on a warm day, typicall never seen it above 2/3

Only time I ever seen it start into the red was 6 lanes of I-80 stopped outside Chicago, 95 degrees outside (probably 110 in stopped traffic) and the A/C running. Revving the engine would bring the temp down.

JOhn Mc

88 Dolphin 4 Auto

[zero]

Its hanging around 1/3. I've never had any problems with cooling. I'll see it creep up a little on a hard climb on a warm day, typically never seen it above 2/3

Only time I ever seen it start into the red was 6 lanes of I-80 stopped outside Chicago, 95 degrees outside (probably 110 in stopped traffic) and the A/C running. Revving the engine would bring the temp down.

JOhn Mc

88 Dolphin 4 Auto

I recall when the "fix" for an overheated car stuck in traffic was to rev the engine AND turn on the heater full blast. That makes things real fun on a 100 degree day.

[Derek up North]

Its hanging around 1/3. I've never had any problems with cooling. I'll see it creep up a little on a hard climb on a warm day, typically never seen it above 2/3

JOhn Mc

88 Dolphin 4 Auto

So it would appear that though temperatures under the hood were high, the fan was operating needlessly.

[Derek up North]

I recall when the "fix" for an overheated car stuck in traffic was to rev the engine AND turn on the heater full blast. That makes things real fun on a 100 degree day.

Been there, done that, had the scalded feet to prove it. Not so bad on a nice day in a convertible with the top down (other than the feet). Not so good if it's pouring with rain.

[Totem]

Lol @ coming on needlessly... It's doing what it's supposed to, move air through the radiator and cool things. My electric fan runs "needlessly" too in my Buick. Was 19 this am. If your fan isn't running and your motor is you'd better be worried...even in the cold. If its stuck on full blast then maybe you have a drive problem. We have covered this before, but its very funny.

[ShaggyRV]

Well since I replaced the fan it has not gotten hot enough to fully engage. These fans as you can see from the link I posted have 4 different levels of engagement. I'm sure the autozone clutch I got was bad as I never heard it roar even in 95 deg temps with A/C on. It however was easily stopped by sticking a piece of rolled up paper in there after the vehicle was fully warmed up. That is the sign of a bad fan clutch. I saw many posts online about overheating at highway speeds and almost all replies said there is no way a fan clutch can cause that as they pretty much freewheel at highway speeds. This is far from the truth. The fan once warmed up will be operating at one of the four settings with even the lowest hookup not being a freewheel situation. I am just saying to all just because you put a new one in does'nt mean it was a good one. If you still have the same problem afterwards. I recommend the Aisin replacement that was designed for our engines. I fully expect that all of my high temps at highway speeds and climbing hills are solved for now.

[Derek up North]

Lol @ 'very funny'.

[Derek up North]

I took a bit of time and read the article (only for the 2nd time) about 'adjusting' the viscous coupling. He succeeded in adjusting it so that it started engaging at 45C* (113F) and was at 'Stage 3' at 85C (185F). This sounds great, EXCEPT that the thermostat spec'd for the 22R-E only STARTS to open at 190F (fully open at 212F).

http://personal.utulsa.edu/~nathan-buchanan/93fsm/engine/53services.pdf

So what's the point of using engine power to blow air (especially full blast) across the radiator while the thermostat is still fully closed and there's NO water flowing through the radiator? Sounds pretty 'needlessly' to me. Or the guy's numbers are wrong!

BTW, in my vehicles with electric fans, it's normal for the fans to be not running with the engine running, unless I'm stuck in traffic. Especially when it's cold.

*He also quotes a U.S. spec of 35C (95F)!

EDIT: Must be the difference between the 'under-hood' temperature and coolant temperature.

[5Toyota]

THE AUTOZONE ALTERNATORS ARE JUNK I WOULD NOT EXPT THE FAN PARTS TO BE ANY BETTERI BUY NOTHING FROM THEM. wonder if you took that fan clutch and through bolted it solid put it on see how it cools. but from the des it had to be bad

[waiter]

I have a theory on the air flow thru the radiator. When it gets warm in the spring I'll test it and see if there is any reality to my theory.

Theory.

The fan clutch should never turn on at straight and level highway speeds, there should be plenty of airflow thru the radiator to keep the engine cool.

Because of the oversize frontal area of the Toyhouse, this tends to impede the natural air flow thru the radiator at highway speeds (50 mph) IMHO,

The toyhouse creates a large bow wave in front of the toyhouse that blocks/reduces the radiator air flow that a normal pickup truck would see. The air inside the wave is standing still or at a very low speed. At 50 mph, I would estimate that this wave is approximately 5 ft in front of the truck. To prove this theory, I plan on putting some tufts (small yarn threads used in aviation to test air flow) on the front of the hood and compare this airflow with a standard pickup truck. I also have a couple old airspeed indicators at the hangar, I may run a tube out in front of the radiator and measure the airspeed (pressure) of the air that enters the radiator in front of the truck, and compare this with a standard pickup.

If this is true, this would explain why the the cooling fan cycles a lot at highway speeds. i.e although the truck is moving at 55 mph, the airspeed thru the radiators like the truck was only doing 15 or 20 mph. A reduced air speed thru the heat exchanger (radiator) will cause the air to be hotter, this would explain why the fan cycles more.

More thoughts - I've been thinking of electric. in particular a 2 stage system, one small fan would kick on at 190, another larger fan would kick on at 200. The smaller of the two fans (190) would do most of the highway cooling to help with the airflow. the larger (200) would kick in on hard climbs or hot days sitting in traffic with the A/C running.

This is all still in the dream stage. I talk myself into it, then out of it.

John Mc

88 Dolphin 4 Auto

[Totem]

There is no adjusting a viscous fan drive. They are sealed and non user serviceable . The bimetallic spring turns the reservoir valve , controlling fluid. There is no stage 4 and no adjusting a fan drive. I'm not sure what repair document you have posted here but I don't see anything where any mechanic claims to. If you do have a mechanic claiming to adjust a fan drive you probably got ripped off. Stages? Malarkey .

[waiter]

I agree. mine seems to be all on or all off. When your traveling down the road, there is no mistaking when it comes on, you can defiantly hear it.

JOhn Mc

88 Dolphin 4 Auto

[Totem]

Correct and the noise is raw unbridled airflow! Which is what it supposed to do. When you can hear it really loudly it's clutch plate is fully flooded with fluid similar ATF fluid, which makes the grooves of the clutch bite each other and spin much like how a wet glass can pickup a playing card off of a table. I think Derek is just trying to make me go bonkers here...I don't even think he is serious. It's funny John, that you say on-off , that's exactly what a bimetallic viscous clutch is and what it's street name is also; an "on/off" drive. Now I will enlighten you all on the newest generation of cooling tech which actually talks to a computer and regulates fan speed based on engine needs not just heat expansion of a spring.. Called cool logic...But these drives only benefit highly computerized and large heavy diesel and automotive applications. Being worried about parasitic loss on something that is overloaded and weak as a toy homes motor (4 or 6 cylinder) is really moot; it's a bit like a tortoise wanting .000005 horsepower to be more like a hair that is 6 days ahead. You would reduce far more loss by removing the AC compressors belt anyway as it truly

isn't doing anything to improve fuel economy. cooling a motor improves fuel economy. If you put the

wrong fan drive into an application and it's spring and design characteristics aren't aligned with the

application implicitly you will end up thinking you have a bad drive. The only modicum of truth to this thread is that the aisin stock drive would be the best fit for the application. Another interesting tid bit for you folks is that there s no such thing as a "refurbished" fan drive. You either get new or used. You can call me a liar, it really doesn't matter to me; I will laugh as I watch them being produced, engineered and designed every day. The voodoo witchcraft assumptions postured by some in this thread on fan

drives are just that.

[zero]

There is no adjusting a visvous fan drive. They are sealed and non user serviceable . The bimetallic spring turns the reservoir valve , controlling fluid. There is no stage 4 and no adjusting a fan drive. I'm not sure what repair document you have posted here but I don't see anything where any mechanic claims to. If you do have a mechanic claiming to adjust a fan drive you probably got ripped off. Stages? Malarkey .

I don't know what document was being referred to . . but there are plenty of 2 speed and 3 speed viscous fan drives around. All I've seen are on medium and heavy duty diesel trucks and busses. Some even have complete lock-up ability. The viscous drive on a light-duty Toyota only gets up to a 85% lock-up. Pretty much the same as the torque converter in a Toyota truck (auto trans with no lock-up). I have never seen anything but a "on-off" type visous drive on light-duty trucks. Note "light-duty" is a weight class and not a "feeling" about something being built well. No pickup trucks in the USA are anything but light-duty although a few diesels have medium-duty engines in them. A $60,000 Ford, GM, or Dodge diesel dually truck is still in the light-duty class.

A few companies that make multi -speed fan drives are Horton, Arctis, DM Advantge, etc.

[Derek up North]

Well, both these guys seem convinced that they can be serviced, with photos showing the operation. Shaggy, have you still got any old couplings lying around? Feel like trying to take one apart?

http://neuralfibre.com/paul/4wd/tuning-and-understanding-your-toyota-viscous-fan-clutch

http://www.offroad80s.com/how-to-top-up-your-fan-clutch-and-do-the-blue-fan-clutch-mod-t1160.html

"The Genuine Toyota Blue Fan Clutch is one of the very few that is ADJUSTABLE - however the original one, I am advised can be topped up with oil no problems."

So it appears (to this guy, at least) that there's more than one version.

I also seem to recall reading someone 'adjusting' the viscous coupling by changing the viscosity of the silicone fluid. Never gave it much thought beyond thinking what a PITA it would be trying to track down the different fluids!

[zero]

Well, both these guys seem convinced that they can be serviced, with photos showing the operation. Shaggy, have you still got any old couplings lying around? Feel like trying to take one apart?

Just about anything mechanical can be altered so I guess it's fair to call it an "adjustment." I had problems with my Chevy diesel RV getting hot. It only happened on slow-speed hill climbs so I suspected the fan-clutch. I changed the position of the bi-metal spring to make it come on at a lower temp. Was no big deal - but I didn't really fix anything except maybe lose a little fuel mileage. The fan being off or on made little difference with the problem; it still got hot on hill-climbs. Ended up being a coolant flow problem which I finally fixed. Chevy and Ford have big fans and it's easy to tell when they come "on." They sound like a small helicopter under the hood.

[Derek up North]

"My fan clutch is genuine 2 months old (they are not cheap!) Part code: 1621017021"

From here: http://www.toyodiy.com/parts/xref?s=1621017021&mU=on

it appears to be for a Landcruiser. No idea if the same coupling would (or should) be bolted to a 22R-E or 3VZ-E.

[Totem]

wow so you managed to find one clutch that is serviceable. Mine isn't blue. So much for that applying to me. Even if you can unbolt it you are no engineer and do not have the tester chamber to properly calibrate the clutch. bench testing is impossible without installation even in your article it requires "guesswork". I do yield that you seem to have found a clutch that is not rolled shut; but I would also question the longevity of such a model because of that fact (i.e. thats probably why it leaked in the first place.)

I see folks playing with different fluids and volumes all day. It often results in smoke, failure and one of the most horrid smells on earth. The computer aided engineering that goes into mating clutches to fans to achieve proper application specification requirements is best left to an expert. By the way; did I ever tell you the story about explosions in drives? If you don't know what you are doing you can cause the thing to explode or fan blades to become projectiles. Stick to buying one...

[zero]

I have a theory on the air flow thru the radiator. When it gets warm in the spring I'll test it and see if there is any reality to my theory.

Theory.

The fan clutch should never turn on at straight and level highway speeds, there should be plenty of airflow thru the radiator to keep the engine cool.

Because of the oversize frontal area of the Toyhouse, this tends to impede the natural air flow thru the radiator at highway speeds (50 mph) IMHO,

The toyhouse creates a large bow wave in front of the toyhouse that blocks/reduces the radiator air flow that a normal pickup truck would see. The air inside the wave is standing still or at a very low speed. At 50 mph, I would estimate that this wave is approximately 5 ft in front of the truck. To prove this theory, I plan on putting some tufts (small yarn threads used in aviation to test air flow) on the front of the hood and compare this airflow with a standard pickup truck. I also have a couple old airspeed indicators at the hangar, I may run a tube out in front of the radiator and measure the airspeed (pressure) of the air that enters the radiator in front of the truck, and compare this with a standard pickup.

If this is true, this would explain why the the cooling fan cycles a lot at highway speeds. i.e although the truck is moving at 55 mph, the airspeed thru the radiators like the truck was only doing 15 or 20 mph. A reduced air speed thru the heat exchanger (radiator) will cause the air to be hotter, this would explain why the fan cycles more.

More thoughts - I've been thinking of electric. in particular a 2 stage system, one small fan would kick on at 190, another larger fan would kick on at 200. The smaller of the two fans (190) would do most of the highway cooling to help with the airflow. the larger (200) would kick in on hard climbs or hot days sitting in traffic with the A/C running.

This is all still in the dream stage. I talk myself into it, then out of it.

John Mc

88 Dolphin 4 Auto

You can buy a "ready to install" four stage electric fan kit. It will draw near 40 amps though when at the highest speed. Not something I have any desire for in my Toyota.