The Fan Clutch (clutch fan / fluid coupling) Thread

My fan roars while revving at startup. However, I am not hearing it roar or seeing a change in speed once the van is at normal operating temperature driving around town, immediately stopping and lifting the lid to rev again. New fan clutch in my future?

My engine recently got hot driving up some grades in 95F heat so I have been trying to work on the cooling system. I have replaced the radiator cap and plan on putting in a new Toyota thermostat with AISIN gasket. I also ordered this electric pusher fan: Spal 30101505 12" Straight Blade Low Profile Fan. I think at first I may just wire in a relay and switch directly to the battery so I can turn the pusher fan on and off from the dash for those more extreme situations. I can also use it to cool the engine bay down a little after turning the engine off. Researching the thermostat fan controllers online it seems like they are pretty hit or miss. They either fail often or people have issues getting them to activate the fan at the right temperatures. The flexalite one that seems the most reliable is over $100 and making my cooling system more robust is already going to be a multiple hundreds of dollars ordeal. Not sure if I should dig into replacing the water pump quite yet. Not quite ready to have the van down while waiting for my radiator to be recored or figuring out using the Griffin Aluminum one VanCo used. I am sure it needs it all though.

The clutch fan is not designed to engage at "NORMAL" operating temperatures. Your engine will have to get pretty warm for it to kick in and then it is a varied degree of engagement relative to the air temperature coming off the radiator. According to Haydens website, a thermal fan clutch "Engages at about 170° radiator air temperature, (about 30° lower than coolant temperature)." I believe this would be the temp of the beginning stage of engagement. You likely won't get full engagemnet and roar until 10-20 degrees higher.

That makes sense, though I rewatched Tim's video and tried to replicate it with my van and it seems like I am not getting any roar like his:cnfsd:. I guess I was assuming (wrongly?) that since my cooling system seems to be on the weak side that revving at a standstill would make the fan roar. I ordered an AISIN clutch to replace mine anyway just in case, no idea how old this one is. Also ordered new Gates upper and lower radiator hoses.

You can't go wrong with the Aisin fan clutches. Anymore, if/when I get another van with unknown history, considering the importance of this component, I would replace with a new Aisin and consider it preventive maintenance. I'd also replace the thermostat (just because) as I feel it's cheap insurance and makes me feel more secure about getting to where I'm going. BTW, that Aisin fan clutch I installed (earlier this thread) has over 40k trouble free miles on it now and is still working flawlessly.

Regarding the roar when hot, that will depend upon air temp coming out of the radiator. I'm not sure about actual air temps, but suspect it to be somewhere in the range original claims. Since there is a direct correlation between water temp and air temp, I would expect the fan to be 100% engaged @ around 200 deg F coolant temp. You can either put an aftermarket temp gauge on the van (to monitor) or you can put a meat thermometer in the coolant fill neck. Just remember that you're dealing with potentially dangerous stuff here. Keep your hands out of the belts and fan blades! Also be aware that removing the fill cap can result in scalding injuries. So please take appropriate precautions to protect yourself..........or just don't risk it! Tim

Glad to hear that AISIN fan clutch you put in is still going strong. I am excited to tear into replacing mine when it comes in the mail. Perhaps the roar will change after replacement or I need to more accurate temp monitoring like you say to really tell what is going on. I have been meaning to at least get an IR laser thermometer thing. Either way good insurance putting a new one in like you say.

On the topic of aftermarket temperature gauges I have been doing research on what to install in my van. I will post some things I have come across over in the Cooling system Mods thread so I don't muck this one up too much.

I just got my van out of the shop after a lot of work to cooling system. Had my radiator sent up to Ability Radiator in Yuba City, CA for high efficiency core rebuild, new filler cap and housing, new head gasket replacement after that was confirmed as failed. Just driving the van from the shop to my place. Definitely did a lot better than before, but not quite cool enough on the temp gauge to make me 100% happy. My overheating problems before were an absolute nightmare. I would be driving 17 minutes to work, climbing up a hill towards the end, and then getting off the exit and almost as soon as I came to a stop light, my temp would creep up pretty quick and if I didn't shut it down right then and there, it would redline. It actually did redline a few times, hence my burned out head gasket. I was loosing way too much coolant through that breach, so the pattern was, temp would creep up, and then when I came to a slow section of road or got caught in traffic, it would just rise to the redline. It was a fast death for my headgasket.

Now I've got a lot of my ducks in a row on this one. The normal day driving temp in San Diego now is just barely below half (9/20ths I'd say), and when climbing larger hills, it creeks up to a little above half, but not quite a full 2/3. Maybe like 3/5ths. Only difference now from before is once up on top of that hill and turning off the highway and getting caught in traffic, is it makes a recovery back down to just below half. I have definitely seen this needle down to the 1/3 or 2/5ths mark at normal operating temperature in this van's prior life. So although a lot has been fixed and I'm feeling kind of good about that, I've had too many overheating experiences to not be cautious of failing in a different area. I looked up fan clutch and it brought me to this thread. Do you think based on these symptoms, it would be beneficial for me to replace it? I was thinking of getting the Aisin as Tim pointed out after having good luck with it. It may be almost twice the cost of the Hayden, but if it's half the headache, than it's worth it :thmbup: I also plan on attempting to replace the clutch myself. I've never done this before, but I'm pretty mechanically inclined. Is there anything special to know about this particular one, or does anyone have a tutorial on how they did this? Would it be beneficial to look up how to replace fan clutches on various car models, or is there something about this one that makes the directions very specific?

Personally I don't trust the water temp or oil pressure gauges. IF it were my car, I'd invest in an actually gauge to read coolant temp, then go from there. I realize you have a history w/this van and experience watching the temp needle in different environments but I'd first make sure you know where you are at currently.

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Originally Posted by Usaviator

[...] fan clutch [...] Do you think based on these symptoms, it would be beneficial for me to replace it?

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Based on your initial symptoms (before HG replacement), YES.

But, based on your recent issues, perhaps not. I would still replace it if it's history is unknown (especially if it's possibly original). They're affordable and they do wear out.

Quote:

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Originally Posted by Usaviator

I also plan on attempting to replace the clutch myself. I've never done this before, but I'm pretty mechanically inclined. Is there anything special to know about this particular one, or does anyone have a tutorial on how they did this?

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I can personally assure you that it's so easy a girl can figure it out. :lol: Removing the passenger side access panel will allow you to remove the fan shroud and see what you are doing (reassuring if you're a noob), but is not necessary. The fan needs to come off the clutch, then the clutch comes off the water pump. The latter can get interesting because sometimes one or more studs come out of the water pump instead of the nut(s) coming off the stud(s), and you likely will have to grip the belt (careful, don't pinch your hand between belt and a pulley) to break the fan clutch nuts free. But it's all easily addressed.

Gwen

So I lifted up the drivers seat just to get a look at the fan and see what I'm working with here, and I noticed something strange... no fan shroud. Is that a problem? I think it was there before, but now I'm not totally sure if it was there or not or if my mechanic accidentally forgot to put it back on. I understand it could be a problem for sticking your fingers in there, but does it have a purpose to cooling the engine better? Isn't it supposed to hook onto the radiator and direct the air directly through it? Anyways, just wondering your thoughts on this. I'm sure this is a noob question since I'm pretty sure almost every car has a cooling fan shroud, but I never thought as to whether it made a difference in the cooling system or was only there to protect you from sticking your fingers in there.

Yeah you want that fan shroud in there for sure

Since our radiators are up behind our floor boards, the shroud is a critical part on our vans. For the radiator to transfer heat it needs to have air flowing through it. Without the shroud air will take the path of least resistance..........& much of it will bypass the radiator. To exasperate the problem, the fan will be getting cooler air and will not kick-in fully. In short, it doesn't matter how good your radiator or fan is if there's no shroud to direct air through the right places. Tim

Ahhh, thank you for that. Very good news. I think it was running cool enough I can make it back to the shop. And I called my mechanic and sure enough, he had a shroud lying around he was wondering where it went. Between the new fan clutch coming in and the shroud being put on, I'm fairly certain that this will cover all the bases on my cooling system and this will finally run nice and cool.

Changed my fan clutch today. PO had an aftermarket one in there. The finned body part of the AISIN is definitely thicker. Makes me feel better about it.

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Originally Posted by Usaviator

, climbing up a hill towards the end, and then getting off the exit and almost as soon as I came to a stop light, my temp would creep up pretty quick

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Sounds like my commute...

I recommend an external temp gauge, also for the trans.
I would not of fixed the issues had the PO not installed one.
I was able to correct them before the HG suffered.

There are so many things I could think of doing on this van. It's in pretty great shape really, but of course there is an endless amount of work and upgrades I could put on it, but me and my wife are moving cross country in a couple months, so this van needs to sell in the next month. I will be listing it on here as well as craigslist within a week or so.

Ran across this write up on Toyota fan clutches. I'm not sure if it's already on the site someplace or if it's even applicable to the 80s van fan clutches, but it seemed worth a read.

http://neuralfibre.com/paul/4wd/tuni...ous-fan-clutch

That was informative thank you. Gets me thinking on whether I would go to the trouble of adding silicon or to the trouble fabricating a shroud for electric fans and wiring them in. Next time my clutch gets weak that is. Funny that there was person in the comments with an overheating 87 toyota van

I agree that aftermarket brands might not measure up, but come on, do you really think some guy bumbling around in his garage has learned more than the engineers who designed this clutch? I'm sure his "scientific" calculations as to the exact volume of silicone would far exceed theirs....... :yes:. Regarding silicone levels, if you end up with not enough silicone, the fan will slip (won't move enough air). If you end up with too much, it will not disengage. If I had to guess, I'd speculate he has hydraulically locked his clutch. Yes, this would be better than a clutch that doesn't engage, but it would unnecessarily rob power and decrease fuel mileage. IMO opening a working clutch in an attempt to improve is a silly waste of time. I understand these tactics become necessary when things break and parts are NLA, but when you can get a new OEM clutch for ~$90, it just doesn't make sense.

These OEM clutches last about 150k miles. Considering what they do and the extreme environment they operate in, I say replace with a new OEM unit (Aisin) every 150k miles (or when it malfunctions) and forget about it. Tim

Does anyone have any tips for how to actually remove an old clutch? Mine seems pretty helplessly stuck onto the shaft.

Been broken down in Wyoming for a couple days with overheating issues.

*update*
... nevermind, obvious answer is a big enough pry bar

Quote:

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Originally Posted by Kyle

Does anyone have any tips for how to actually remove an old clutch? Mine seems pretty helplessly stuck onto the shaft.

Been broken down in Wyoming for a couple days with overheating issues.

*update*
... nevermind, obvious answer is a big enough pry bar

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ugh,, sorry to hear about the breakdown,,, hopefully you're sorted and rolling now.

Do you need a special wrench (and or any special tools) to remove the fan clutch on these vans? I think mine needs replacing.

Ordinary tool sets probably won't reach it, but, the guy across the street is a Honda mechanic and had 2 really old box-end wrenches that were super long and thin... both were 6-point 10mm wrenches with only a one-sided wrench and just a long shaft on the other end ... about 12" long... the "Honda" brand wrench was close but no cigar, and the "Snap-On" brand wrench had more offset and just barely worked. With it I was able to pull the clutch and fan off the water pump without moving anything else at all. It would be worth buying one long wrench if you can't borrow. The 4 nuts were already a bit rounded from some previous butcher, but, you can reuse the fan-attaching nuts for the "clutch-to-water pump" studs and buy new flanged nuts for the "fan-to-clutch" studs. I was able to wiggle the clutch and fan as one piece in and out of the bottom of my 2wd van... which now makes me wonder if my entire shroud is still in place.

Update:

Wow---it's missing... (The bottom piece of my shroud)

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Originally Posted by Tan Van

Ordinary tool sets probably won't reach it, but, the guy across the street is a Honda mechanic and had 2 really old box-end wrenches that were super long and thin... both were 6-point 10mm wrenches with only a one-sided wrench and just a long shaft on the other end ... about 12" long... the "Honda" brand wrench was close but no cigar, and the "Snap-On" brand wrench had more offset and just barely worked. With it I was able to pull the clutch and fan off the water pump without moving anything else at all. It would be worth buying one long wrench if you can't borrow. The 4 nuts were already a bit rounded from some previous butcher, but, you can reuse the fan-attaching nuts for the "clutch-to-water pump" studs and buy new flanged nuts for the "fan-to-clutch" studs. I was able to wiggle the clutch and fan as one piece in and out of the bottom of my 2wd van... which now makes me wonder if my entire shroud is still in place.

Update:

Wow---it's missing... (The bottom piece of my shroud)
It was 9 degrees this morning so I don't care right now, but, a Spring-project is in the plan...
If anyone has a cool home made shroud-bottom can you post a photo and a "how-to" ?

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Thanks TanVan. Looks like the autoparts store rents fan clutch wrenches. Do people usually replace the water pump when down there?

HISTORY — Just finished fixing all culprit issues associated with overheat, fan clutch, belts, water pump, radi cap, thermostat, hoses. Runs just fine and behaves normally EXCEPT ...In traffic or other warm-running situations, the gauge creeps. In Los Angeles, this is going to be a double-whammy issue as spring/summer approaches, so I want to figure it out right now. My fan clutch very audibly is engaged after a cold start, so I know it CAN work, the thing is, after the temperature gauge gets past half, I never hear it again and a quick test right after I shut it off gives no resistance. Soooo, is it possible that the clutch in there is just a dud? Could I have done something dumb or wrong? is not enough hot air getting to the bimetal tstat? (radiator clogged up?) It's a brand new (less than 500 miles) Aisin clutch from RockAuto.

HISTORY, PART TWO -- I was sitting in low speed traffic, and the thing did come on right after the temp gauge hit halfway --- hmmm. It's worth noting that it's never overheated, but it's gotten too close for my comfort on several occasions, usually at around 25 mph on a congested freeway. Before I did the work, the temp gauge would live at 1/4 of the way up (presumably from a stuck open thermostat.) Any thoughts? Am I just being scared over nothing? My next step is to blast the front of the clutch with a heat gun and see if the bimetal moves predictably.

RESOLUTION — I did learn a bit about fan clutches and, at least in my case, the Aisin FCT-37 I had (with the red mount) never worked in my 2WD auto application.

I discovered this after being (again) hyper sensitive about the van cooling, and noticed that no matter the situation, the red back clutch never activated unless it was a cold start situation, when the oil viscosity locked it on regardless. While idly online shopping, I saw that there was another AISIN clutch fan listed as fitting the van, the FCT-19, which has a black mount and seemed slightly smaller. I did some research and saw that it was listed as stock for the very early (2.0, likely) motors At the time, it was somehow listed on amazon for $15 (whoa!!) so I grabbed one just to experiment.

After days and days of garbage heat and me relying on the A/C, the new clutch fan works exactly as it should. It comes on post freeway drives, in stop and go, and when heat from the condenser gets to it. The FCT-19 is definitely physically smaller and less heavy duty (see side by sides below) but it works perfectly, so it's a keeper for me.

Has anyone else had this experience, used both, or did I really just end up with a weirdly defective AISIN product? It seems highly unlikely, but I can't explain it otherwise.

https://i.imgur.com/aRnS6BS.jpg?1

https://i.imgur.com/jwCqITr.jpg

https://i.imgur.com/2Z795lZ.jpg

my aisin fan clutch seems to engage more often at a lower temp than needed, i thought at first maybe it was the aluminum radiator dissipating more heat onto it but that doesnt seem to make sense, i thought about trying to tweak the bimetal valve but decided to leave it alone as at least its erring in a safe direction...
the fan clutch in my 85 which doesnt get driven often is always engaged...i believe its an aisin as well, so i guess they fail in different ways...

Quote:

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Originally Posted by boogieman

my aisin fan clutch seems to engage more often at a lower temp than needed...

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I bought 2 separate brand new Aisin clutches ,(red), that both ran way too long after startup-- sometimes for 2 miles or more in the dead of winter on every startup even when the engine was already warm...

I opened it up and drained about 5 or 6 cc's of the silicone fluid out of it and tried again. The new (RED) Aisin clutch just had too much fluid in it from the factory. I got lucky with my estimated quantity to drain because, now, the clutch fully engages only at startup -- it stops howling after about 15 or 20 seconds -- and, most importantly, I clearly heard it re-engaging this summer during really hot drives (high 90's and high humidity--freeway + street)!

This saved me from the "crap-shoot" of exchanging it and trying a 3rd new clutch all within 4 months.

(and, for reference, the van cooling system has no negative issues of any kind... and the front and rear heat also both work splendidly ---- the original clutch was always "locked on" which is why it was replaced ... and I expected the new aisin clutch to "fade out" after startup like it's supposed to, and it almost never did...and the replacement they sent was even worse... so, I saw the "silicone fluid tweaking" on a 4-runner site ---- and it worked.).

Quote:

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Originally Posted by timsrv

Use Toyota #90916-03046 180° F T-stat. The gasket you need is #16325-63010.

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is Aisin OEM Toyota? or is Aisin aftermarket? ordering a few things from rock auto, but am confused on what's aftermarket or not. is toyota OEM only available from toyota?

getting the aisin fan clutch and figured it'd be a good idea to replace some things that haven't been done while I have the chance to. (i have very limited mechanic experience.. which is probably obvious haha) should i replace the coolant hoses or anything else just for good measure or inspect them first? or since the fan clutch is confirmed not working, should i do that first and then see where my temp gauge is at before replacing anything else? i don't really have time to waste as this is already effing up my plans, but I want to be thorough so i'm not having ANY overheating issues since I'm heading to the south.

Toyota buys parts from several outside manufacturers. Denso and Aisin are two of the big ones. Denso and Aisin make parts for other manufacturers as well (not exclusive to Toyota). In many cases, when you purchase parts from Toyota, The only difference is you'll get a red box that says "Toyota" AND you'll likely pay much more $$$. For this reason, whenever I can purchase OE equivalent parts at discount prices that's what I'll do. In the case of this clutch fan, Aisin was the original supplier to Toyota, so Aisin/Toyota are essentially the same.

IMO, if you still have any original hoses they should be replaced. It's your risk though and also your budget, so use your best judgement. Good luck. Tim

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Originally Posted by dirtritual

as this is already effing up my plans,.

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If I don't want anything effing up my plans, I make sure to plan around a thirty two years old appliance:roflmao:

Can anyone who has driven both a TV and a Previa confirm for me that the fan on the TV should sound, at startup, like that of a Previa? B/c I have never heard that fan roar from my new-to-me TV. I recognize it from the fan-clutch-related YouTube videos, though.

Due to several variables the sound would be a bit different, but yes, both are clutch fans and should have a roar at start-up that goes away after a few good revs.

Attachment 10226

decided i wanted to play around with a dead aisin fan clutch and did some research, land cruiser guys are using what called diff fluid for rc cars/trucks, its silicone and comes in many weights, and sold at hobby stores..most of the guys were using 10,000 cst weight oil, this ofna brand was the cheapest ($10 delivered for 4oz), looked of similar vicosity to a video i watched a guy using the actual toyota fluid...anyway i used about 2oz half the bottle, my clutch was pretty dry when i split it. fortunately all my clutches are working well at this time so ill have to get back on a report, but i think this could be a lifesaver if you were over heating out in the baran desert and needed to have the fan do more for you...

Yes, having hope of a spare fan clutch would certainly be on the list for a longer trip.
Wish I had one when I realized the mechanic had been wrong to assure me mine had been 'fine'. <;~l

For anyone that needs to remove/install the fan clutch for whatever reason, the extra long 10mm 12-point box wrench I picked up works wonders. No more worrying about rounding the four fan nuts if they're on tight and then having the fear set in about not being able to get the fan off. :LOL2: Also makes getting the nuts back onto the water pump pulley bolts a snap too. May very well be the best tool I've bought solely for my TV, so thought I'd share. Happy wrenching!

GEARWRENCH 10mm 12 Point XL GearBox Double Box Ratcheting Wrench - 85910 https://www.amazon.com/dp/B002V037SY..._3WgZEb1G0JW5Q

Did a first start today, after doing a head gasket job, and it all looks sounds good so far,,, though brand new Aisen fan clutch seems continuously engaged....

I noticed even with engine cool, just starting up, the fan clutch seems to be engaged, and doesn't shut off.

...20 minutes at about 3,000 RPM, temperature gauge is at a quarter and the fan clutch is still engaged.
Median operating temperature usually shows the guage at center.

I don't remember seeing this before, seems odd. https://static.xx.fbcdn.net/images/e...1/16/1f610.png

Red base, if that makes a difference.

VIDEO...
https://photos.app.goo.gl/wyp8DnQYkyhtyLH29

It's in the nature of fan clutches to be engaged when cold as the silicone inside is too viscous to slip. There are variables as to how long it will engage cold depending on how hard you are revving the engine, but ~ 30 seconds of high revving should warm it sufficiently to slip/quiet down. After that it should stay disengaged until hot air from the radiator rotates the by-metal coil enough to change the internal valving. Many useful posts in this thread. Be sure to see post #19. Tim

I'll give it a try again today, but really seems like mine is waayy off.
Reminds me of the time I did a full rebuild, installed an OEM thermostat... which didn't open!! :dizzy:
It's important to be wary, whether we bought the best, or not.

How 'bout 20+ minutes @3000 rpm. Engine never managed to get above half of operating temperature.
I tested an older one as well. Got up to operating temperature no problem, and kept on going up, up, up. Doesn't function.


Parts Avatar in eastern Canada accepted a warranty return, but they told me they'd ''get back to me within 24-48 business hours'' with details for return... whaaat does that even mean! 4 daze, and tumbleweeds so far. 48 'business hours' over an 8 hour day,not including weekends,, and it could be 9 days before it starts it's 2 week trek across country.. then another 2 weeks for return post of a replacement. Glad I've got another vehicle. :dizzy:

Quote:

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Originally Posted by timsrv

It's in the nature of fan clutches to be engaged when cold as the silicone inside is too viscous to slip. There are variables as to how long it will engage cold depending on how hard you are revving the engine, but ~ 30 seconds of high revving should warm it sufficiently to slip/quiet down. After that it should stay disengaged until hot air from the radiator rotates the by-metal coil enough to change the internal valving. Many useful posts in this thread. Be sure to see post #19. Tim

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Yeah, sounds like you got a bad one. Usually when they fail they don't engage at all, and the result is overheating. At least you didn't have that issue. Good luck with the next new one. Tim