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Thread: The Fan Clutch (clutch fan / fluid coupling) Thread

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    The Fan Clutch (clutch fan / fluid coupling) Thread

    Replaced radiator and now gets hot when idling too long or low speeds, have not done thermostat. Fan clutch comes on but not till things seem to be too hot? Any ideas as to next move? Randy

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    Administrator timsrv's Avatar
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    Re: overheating problems

    Hello and welcome to TVT! IMO replacing the thermostat should be your next move. They can and do get stuck (I've seen it many times). If it's stuck in a closed or partially closed position, it could certainly explain your problem. OEM thermostats are a bit unique on these vans. There are aftermarket ones listed, but some of them don't fit quite right and/or the travel of the valve is incorrect. For this reason I highly recommend a genuine Toyota thermostat. It's Toyota Part #90916-03046. You will also need the rubber seal that holds it in place. The seal is Toyota part #16325-63011.

    I suspect your problem may actually be the fan clutch, but the T-stat is cheap and pretty easy to do (just consider it routine maintenance). Llamavan has a good write-up HERE that explains how to replace it. The fact that your fan clutch engages is encouraging, but it needs to engage BEFORE the van overheats. Typically a good working fan clutch will engage when the temp needle hits the center or just slightly higher (about 200F), and should stay engaged until temp comes down to 190 - 195F (needle somewhere under half way). If yours isn't coming on until there's an overheat condition (needle around 3/4 or about 220 - 230 F), then it's got a problem.

    If this is the case you have 2 choices. You can go get a new clutch (again I strongly recommend genuine Aisin/Toyota), or you could try to adjust the one you have. If you attempt to adjust, keep in mind this is not much more than a "hail Mary" and could quite possibly be a waste of time or even make the problem worse. Still, if you are financially challenged (like most of us these days) it could be worth a shot. If you attempt this, the 1st thing you need to do is remove the fan unit and separate the clutch from the fan. When you get to this point, the next step is opening the case. Keep in mind that this is a sealed unit and has a specific amount of silicone goo inside, so keep it laying flat and try not to damage the rubber seal or introduce dirt/foreign material into the clutch. Once open you will have access to the adjustment screws inside. See picture below:



    To make the clutch engage at a lower temp, you will need to loosen these screws and turn the plate counter clockwise. How far to turn is somewhat of a guessing game, but I would think a movement of about 1/8" or so would be a good place to start. Good luck and please report back with results and pictures if you have that ability. Tim

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    Re: overheating problems

    Hey Tim thanks for the info, I am going to replace both so it is hopefully solved. I stopped by this summer with the 4wd silver van that you thought looked so clean and is. After this it will be the 4wd drive locking hubs that have been gutted so I am a little apprehensive.
    Do you have a part # for the fan clutch and where is best place to get these genuine Toyota parts? Thanks again, Randy.

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    Re: overheating problems

    Fan clutch ("coupling assy, fluid") is P/N 16210-73010 (same for all vans EXCEPT 1984).

    Here's a few sources for parts:
    1stToyotaParts.com
    toyotapartszone.com
    LithiaToyotaParts.com

    Because Lithia is local to me (Springfield, OR), I've done all my ordering from them for several years now,. Their internet site is fairly new. They are quick to let me know if something is no longer available, and because I can pick up locally, I don't pay shipping.
    I've had good and not-so-great service from 1stToyotaParts. One problem has been waiting around forever to find out something is discontinued, but they have fast service otherwise. My biggest beef with them is that shipping is always a % of the total order price, even for lightweight parts.
    No personal experience with toyotapartszone.

    Gwen
    1985 5-speed window cargo van set up for llama haulin'; 345K ("Trustyvan")
    1989 4WD 5-speed DLX; 410K and an odd sense of humor ("Skylervan")

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    Re: overheating problems

    Hi Randy! I'm glad you found the forum. Llamavan is correct, the part number is 16210-73010. I see it lists on 1stToyotaParts.com for $94.26.

    My favorite place to buy Toyota parts is Tonkin Toyota in Portland, OR, but sadly they dropped their internet parts site. I purchase enough to be on a 1st name basis with the parts guys there, so as a courtesy they still sell to me using the internet price structure. I'm speculating a bit here, but I'm guessing if you went in there and asked if they could match 1stToyotaParts.com's price, they would probably do it.........even if they didn't, at least then you could avoid shipping charges.

    Like Llamavan, I have had the same exact experience with 1stToyotaParts.com. I've received absolutely awesome service on one order, then got completely forgotten about and screwed on another (usually due to some part that is NLA). I had to call them once about an order that I had waited 2 weeks for. Turned out the whole order got put on a back burner because of a stupid shift boot they couldn't get. All they had to do was email me or call and I would have told them to just ship the rest and forget about the boot. Then there's the 10% shipping with a minimum of $9.95 regardless how small and light the package (it sucks to get charged $9.95 S&H for a stupid $1.00 O-ring they could have put in an USPS envelope for 43 cents. I could almost see it if they did the same for heavy items too, but no, they ding you extra when that happens. Due to these issues, I now only use them as a last resort.

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    Re: overheating problems

    Not sure if parts have already been acquired, but thought I'd at least post my experience with http://www.toyotapartszone.com/. They've been helpful on orders, website is easy to follow (especially when you type in your VIN), and pricing seems to be as good as it gets. My LD usually has no interest in ordering parts for me and quote me the highest price they can and tell me it will take 1-2 weeks (at least) to get parts, and this is after they roll their eyes. Cheers, Adrien.
    "When the power of love overcomes the love of power, the world will know peace." - Jimi Hendrix

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    An unorthodox method for testing the clutch fan

    I was playing around the other day and came up with this method of testing a clutch fan. This won't help you identify one that comes on at the wrong temp, but it will tell you if it is functional. If you try this I'd like to remind you that it's at your own risk. It can be very dangerous getting this close to moving fans, belts, and pulleys. Also, don't overdo it with the heat on the thermostat. This is a bimetal coil and can be damaged by excessive heat.

    That being said, it was a fun experiment and a useful way to evaluate a fan in question. Enjoy

    Click on the image below to view

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    Re: An unorthodox method for testing the clutch fan

    ...haven't seen any method that's quicker or more definitive!
    ...Imagine that-an '80's toyo mechanic doing something unorthodox

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    Re: An unorthodox method for testing the clutch fan

    Here's a safer way to test. Note, it's a hot day & the AC is on.


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    Re: An unorthodox method for testing the clutch fan

    it almost seems like i can see the different speeds in the video, i can tell when it gets hot enough, the blades look faster

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    Cooling Fan Stuck On

    Hello All, a few days ago my cooling fan started staying on all the time. As in, when I start the engine its engaged and it never disengages. Fan clutch issue I imagine, but I am not sure how to diagnose what exactly the problem is. I checked all the sensor plugs around the T stat and they are not loose.
    Any pointers would be much appreciated!
    Thanks,
    John

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    Re: Cooling Fan Stuck On

    Sounds like it's time for a new fan clutch. There is a thermostat coil on the front that rotates a shaft. That shaft is probably stuck. You might be able to lube & free it up, but I would consider this a disposable part and simply replace. These typically last 150k miles. If the old one made it that far it doesn't owe you anything. A stuck fan clutch won't hurt anything except your power and your gas mileage. You can expect to see a 3 mpg or more drop with a stuck fan clutch. Tim

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    Re: Cooling Fan Stuck On

    Thanks Tim..... I will check it out.
    John

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    Re: Cooling Fan Stuck On

    That's really funny. My fan probably started to stay on right about when yours did. I bet the temperature change & contraction has something to do with it.

    I will say I'm not too upset with my fan being stuck on. I haven't had heat soak once in these 90+ temps.... I'm not really noticing a change in gas mileage; I probably burned just as much stomping on the gas pedal every time I had heat soak.

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    Re: Cooling Fan Stuck On

    Went ahead and replaced mine, now that I have a working one I don't think the old one ever turned on since I've owned (3 months) it until the few days before I replaced it when it was stuck on. The old one was packed with dirt in the metal coil from PO's trip to Baja. I am holding on to the old one as a spare in case the dirt was the only issue.

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    Re: Cooling Fan Stuck On

    Is it typical that they get stuck 'on' when they go bad? Do they ever break the other way?

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    Re: Cooling Fan Stuck On

    The typical failure is they won't come on.............which leads to overheating. It's better when they stick "on" but not typical. Tim

    Here's more on clutch fans: http://www.toyotavantech.com/forum/s...g-(fan-clutch)

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    Fan / fluid coupling (fan clutch)

    Noticed my fluid coupling assembly (fan clutch) spins independently from the water pump pulley. Is this normal? Should the fan spin without the pulley moving? May be a dumb question...sorry.

    Thank you.

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    Re: Fan / fluid coupling (fan clutch)

    The fan clutch will allow the fan to spin at a different speed than the water pump. There is a bimetal thermostat coil on the front of it. When it gets hot (around 200 deg F) this coil moves enough to start changing the valving inside the clutch. It's a variable change that's linear to how hot the t-stat coil is. Typically the fan will spin whenever the engine is running simply due to centrifugal force, but unless the thermostat is engaged it will spin much slower than the pulley (freewheeling). When the temp gets high and the valving changes, the silicone goo inside gets restricted (this makes the clutch engage). The more it engages the faster the fan spins and the faster it spins the more air it will move. When more air moves there's more heat transfer from the radiator to the passing air. As the air gets cooler, the valving opens and the fan begins freewheeling again. The purpose here is to only turn the fan on when it's needed. Fans that run 100% all the time rob fuel economy and horse power. They also make a lot of noise. A correctly functioning fan clutch is a wonderful thing

    Due to the placement of the radiator and the air flow characteristics in the engine compartment, the clutch fan is one of the most important parts of the cooling system. Due to the viscosity of cold silicone, it's normal to hear the fan engage for the 1st minute or so when the engine is cold. After the silicone is warmed up you shouldn't hear it engage again until your temperature needle hits about half way on your temp gauge. Then it should run briefly and the needle should return to about 3/8 of the scale. It may not run at all during the winter, but it should definitely see some action in the summer.............especially if you have working AC. Here's some pics of the internal workings of a clutch fan.

    Here's the bimetal coil


    Here's a bimetal coil reacting to heat


    Here's a clutch that's opened up


    The black propeller looking thing is directly attached to the bimetal coil. The coil moves this when temperature changes. Depending on it's position, it can block or allow the silicone's passage through the slots in the disc I'm holding.

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    Re: Fan / fluid coupling (fan clutch)

    Awsome info Tim. Thanks. That clip of the coil reacting is great. I got worried when I noticed for the first time the fan spun without any other mechanics moving. I think I read in other thread somewhere someone was fixing their fan clutch because the fan wouldn't roar on a constant basis. Good to know now, it shouldn't be.

    Any tricks or tips to inspecting while still connected and a cold engine?

    It's going to be several days before engine is running and I have fan and belts back on.. In the past, I haven't had temp issues, I have working AC, & I don't think I have any problems here now. But wanted to check if possible while I have things opened up changing belts.

    Thanks

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