Fan Clutch Service

Discussion in '79-95 Toyota Truck Tech' started by Bear80, Jul 22, 2007.

  1. Bear80

    Bear80

    Messages:
    2,951
    Servicing the fan clutch seems to be nothing new for many. I picked up the idea after LandTank wrote up how to adjust the temperature for an 80series LC fan clutch (this is NOT possible on a Truck/22RE fan clutch).

    The fan clutch problem steems from shearing the fluid over time, even just a 10yr period. At 20yrs, like most of our mini trucks, the fluid is pretty much doing nothing. Fresh silicon is the key! Just ensure there is no seeping of the fluid and that the rear bearing turns free without noise.

    I've serviced four 22RE fan clutches this way with great results. Most noteably the A/C keeps blowing cold at idle and low speed 'wheeling. Previously when I'd be out creeping along in low gear, the A/C would only blow ambeint air untill I got moving again. Now I creep around in cool comfort! Not to mention I hear a slight roar when the clutch engages vs. nothing before, and there is noticeably more air being pulled across the radiator now.

    Three of the clutches came off two '86 4x4 trucks, an '87 4Runner and the other off an '85 Celica. All of them appeare to be the same physically inside and out. However, each of the top covers have different numbers. Numbers on the oposing side of the spring mounts ranged from a 4k to 6F. While there is another number on the covers such as 10ck or 7ck. I'm not sure what these stand for. After doing some reading, it seems Toyota only used 3, 4 or 10k fluid regardless of market area. So then the 10ck and 4k could represent the fluid, however the numbers are in opposing areas and on opposing clutches.

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    I chose to use 6k fluid on my refills due to the hotter temps here in South Texas. I would guess that nothing less than 4k should be used and nothing more than 8k unless you're in 100+ areas like AZ. Then maybe 10k fluid might be open for consideration, but I wouldn't do a full fill of just 10k fluid. The fluid is mixable to make any range of weights, ie. 10ml of 6k with 10ml of 4k fuild will yeild 20ml of 5k.
    Last edited: Jul 24, 2007
  2. Bear80

    Bear80

    Messages:
    2,951
    Here is the fluid I used, it is R/C diff fluid and carried at any specialty hobby shop. The Toyota fluid is harder to come by (other than CruiserDan here on the forum) and been discussed to be under par of the R/C fluid. There is also other weights at the hobby shop and most are made in Japan.

    [​IMG]
    Last edited: Aug 23, 2007
  3. Bear80

    Bear80

    Messages:
    2,951
    Be careful with the four phillips head screws. I recommend that the proper phillips driver be used, however a phillips #3 will work. I used my impact wrench to break the screws, otherwise it can be easy to round the heads when using a hand driver.

    Also the rubber o-ring is NOT replaceable and must be reused! So take note.

    Open and ready for a drain:

    [​IMG]
    *this picture was taken after all the fluid was drained*
    Last edited: Aug 23, 2007
  4. KLF

    KLF Frame waxer

    Messages:
    5,451
    Location:
    Southern NH
    Ineresting. Do you have any long-term results? I've read about doing this project in a few places, but never tried it. I do know that several people have tried it on the 3FE Yahoo list that I'm on, and it's never lasted. They always end up just getting a new clutch.
  5. Bear80

    Bear80

    Messages:
    2,951
    I've found that it takes about 48 hours to get all the fluid to drain out. It is some slow thick fluid. Putting it in the oven for an hour or so at 200* or "warm" will help speed things up. I drain it into an old pyrex tray, this also helps when I pour it out for measurment. Also I try to tip the bottom up and position one of the three disk holes at the bottom to help it drain. Then later I set it flat in the tray. I also highly recommend that anyone doing this measure how much fluid drained out.

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    After a good draining, they've all come to be right around 25ml and this is the amount I put back in. I've also found that a good way to judge if all the fluid has drained is to spin the clutch by hand. I left one to drain overnight and asumed all the fluid was out, but the clutch still spun with some resistance - pretty much how it felt before I drainded it. When all the fluid is drained the clutch will spin freely by hand and you should only feel the resistance of the bearing. This usally takes two full days or putting it in the oven for an hour or two will speed it up to just an overnight thing.
    Last edited: Jul 22, 2007
  6. Bear80

    Bear80

    Messages:
    2,951
    Now for the fill. *Note* the o-ring is back into the top cover. It takes some patience to get the o-ring back into the grove so doing it before filling is best.

    [​IMG]

    25ml of new 6K fluid:

    [​IMG]

    Also there was discussion about how much to fill the clutch with, which is why I measured it. I know exactly how much came out and put that exact amount back in. I pour the new fluid into each of the three holes untill I see it flowing around the edges of the disk:

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    [​IMG]

    This will only get in about 15ml of fluid. For the rest I just pour it on top of the disk and then quickly put the clutch back together.
    Last edited: Jul 22, 2007
  7. Bear80

    Bear80

    Messages:
    2,951
    Watch the screw heads when tightening the cover down. I use the same #3 phillips head from my impact wrench set on the end of a standard wrench. This way I can get it torqued tighter than with a hand driver.

    [​IMG]
    Last edited: Jul 22, 2007
  8. 2ndGenToyotaFan

    2ndGenToyotaFan Ice-Bound Moderator

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    8,928
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    It's complicated....
    Good stuff Bear! FAQ'd :D
  9. Bear80

    Bear80

    Messages:
    2,951
    Nothing more than a few months. I don't forsee how there could be any issues other than a bearing going bad. I've done my truck, my sister's truck and my dad's 4runner -- all doing fine and blowing cold A/C at idle. The other clutch was the first "test" unit and it also is doing fine. I plan to do this on my 80series.
    Last edited: Jul 22, 2007
  10. Tools R Us

    Tools R Us

    Messages:
    17,946
    Location:
    Chandler, AZ
    If the clutch is in good condition, new fluid will restore it to like new performance or if you upgrade to a thicker fluid better than new performance. In the rust belt areas the thermostat spring can rust making the clutch junk, also inspect the bearing for play and look for leaks, ether will make it not worth refilling.

    I have done many over the years with very good success. The early clutches from Toyota came empty and you ordered the fluid type that was needed for how hard the motor was operated. For most here we use 10,000 cst fluid and it makes a big airflow performance increase.

    If the clutch that your refilling has little/no drive, then the fluid is shot, if you mix the new with bad fluid, it's life and performance will be reduced, so try to get all that you can out. Solvents aren't very effective on silicone fluids and can become trapped in some areas of the clutch, contaminating the new fluid, so the slow gravity, heat, wipe, compressed air blowing, etc methods are best.

    IIRC on the mini clutch the "factory fill" is 2 tubes of fluid, 36 ml. Less fluid means that it's sheared more often, reducing fluid life. More fluid can be added, but it must all fit in the reservoir, or it will always be "on", never freewheel. If it's overfilled simply drain a little. My normal refill amount on the mini clutches is 40 ml.

    If the clutch is good or new and you want to improve it's performance, simply adding thicker fluid to the factory fill works well. On the new 80 series clutches I add ~20 ml of 30,000 cst to the factory fill greatly increasing performance.
  11. Bear80

    Bear80

    Messages:
    2,951
    36ml really and a total of 40ml on a re-rill? I got out an average of 25ml pretty evenly from the four of mine. Think Toyota put too little in and adding more will help prevent excessive shearing?

    Any input on the numbers molded into the top?

  12. Tools R Us

    Tools R Us

    Messages:
    17,946
    Location:
    Chandler, AZ
    Toyota put in enough to work, I have found that adding more makes the fluid last longer. You drained and measured, good plan, but think about it. A ml. is very small, how many of them are still in the tray, on the utensils, soaked up in the rags, on your fingers, etc?:D I have tried measuring the drain a few times, it's sticky, thick, nasty stuff and it's hard to account for all of the fluid removed, so there has to be a "fudge" factor.:D

    When the clutches came empty they came with 2 tubes, 18ml ea to fill them with, so that's the number that I use for the factory fill. Have seen some that looked like they had very little in them, so maybe the fill amount has changed over the years. I have put 3 tubes (54 ml) in them and only a couple of times had them stay "on" and had to drain a bit out, so settled on 40 ml for my fill amount on the mini clutches. It's just about imposable to get all of it out, so the number needs to be adjusted slightly depending on how good of a job you did on draining, cleaning.

    The only drawback to adding more is a slightly longer fan roar at startup, takes slightly longer to pump the fluid into the reservoir.

    They are manufacturing marks, probably for quality control, date, mold that it was made in, etc?
  13. yeah, its very good stuff!

    i was gonna FAQ submit this!
  14. Bear80

    Bear80

    Messages:
    2,951
    Always good stuf Kevin!

    I agree with the slight fudge factor. I'd say in my draining measurments I lost 1-2ml. I was very careful not to be wasteful or slopy. With it being around 25ml each time I figured it was a good round number for Toyota to use. That makes sense for Toyota to supply the clutch empty and filled with your preference of weights in the past.

    I think being meticulous with the measurments and factoring in a slight fudge factor will still yeild excellent results. However, Kevin is a great knowledge source and would take his recommendation about filling in the 36-40ml range.
    Last edited: Jul 24, 2007
  15. LeftCoast

    LeftCoast

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    205
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    I smell Mons Venus!
    Nice job. Thanks!
  16. robinhood4x4

    robinhood4x4

    Messages:
    200
    Location:
    PHX AZ
    Anybody know if the 3.0L V6 fan clutch can be rebuilt and upgraded too?
  17. Bear80

    Bear80

    Messages:
    2,951
    yep comes apart just like above. I'd really suggest a good few days to drain. I've had one open for over a week and it's still got some comming out, like maybe an extra 1 or 2 ml.
  18. Tools R Us

    Tools R Us

    Messages:
    17,946
    Location:
    Chandler, AZ
    All of the factory original and replacement Toyota clutches that I have seen can be refurbished and/or tuned. Some aftermarket clutches are riveted, swaged, etc, permanently together and most are poor quality, making them not worth your time.
  19. robinhood4x4

    robinhood4x4

    Messages:
    200
    Location:
    PHX AZ
    Kevin, would you still recommend the 10k cst for the 3.0L here in phx?
  20. Tools R Us

    Tools R Us

    Messages:
    17,946
    Location:
    Chandler, AZ
    Yes, depending on the fan type. If you have that exploding, POS ring type fan, replace it with a new non ring type before doing anything with the clutch.

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