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Thread: Fan Clutch Testing and Repair

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    Registered User mdbrandy's Avatar
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    Default Fan Clutch Testing and Repair

    I'm starting a new thread, since the other one discussing cooling kind of went off on a science tangent....

    I drove home tonight (about 10 minutes, 7 miles), and the engine temp gauge indicated that the coolant was up to temp. Upper radiator hose hard and hot. Open the hood with the engine still running and look at the fan. Spinning, but kind of seemed to be slower than it should be. Turned off the engine and immediately tried to turn the fan by hand. I could spin it with one finger. Sound bad? The factory manual is useless for this - gives you the theory of operation and then just says to check for oil leaks and bent bimetal, and replace as a unit. Is this thing really repairable?
    Mark Brandyberry
    1970 240Z (11/69) HLS30 00215
    1978 280Z (05/78) HLS30 466356
    IZCC #802 & CZC#4028

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    Yes, you can take it apart and refill it with oil... and I'm still looking for the tech article that tells all about it.

    Sounds like the oil has leaked out and it isn't locking up like it should.

    FWIW, the tech article isn't in any of the Z mags, so I'm not sure where I saw it, I'll go back and look some more tonight... I know I just saw one recently...
    "If it weren't for fools, the rest of us could not succeed." Mark Twain.

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    Default

    Originally posted by 2ManyZs
    Yes, you can take it apart and refill it with oil... and I'm still looking for the tech article that tells all about it.................FWIW, the tech article isn't in any of the Z mags, so I'm not sure where I saw it, I'll go back and look some more tonight... I know I just saw one recently...

    Keith:
    When/If you find it, could you post it to the Technical Articles section, or if it's a link to a website, email the link to me and I will rewrite it, if needed; so that it can reside in our club database.


    Howz your camera? Hint, Hint!

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    Default Heres what I found

    Pics can be seen here http://www.pbase.com/bronte/fan_clutch

    Here are the instructions:

    A fan clutch is supposed to be a fluid coupling device that allows the fan to rotate less than the engine speed.

    Unfortunately, a fan clutch can slowly empty it's coupling oil overtime and often seizes. (the oil also can gel/thicken and grab). This means that it turns as fast as the engine! It results in:

    extra wind
    extra cooling
    false temp sensor readings (they are in the high velocity wind stream)
    delayed thermostat opening (it is cooled too much as it is in the high velocity wind stream)
    lots of noise
    possible damage to water pump due to unbalanced fan and torque on the water pump shaft


    Check for a seized fan clutch it by opening the hood with engine running in neutral.

    Rev the engine and listen/watch fan. If you get a wind storm and windy sound from fan area then your fan is seized.


    There are three solutions:

    1. Replace Fan Clutch with new one (~$70)

    2. Recondition Fan Clutch (~$5)

    3. Remove fan clutch + fan and replace with 12V electric fan (~ $50-$200)


    I just reconditioned mine. It went pretty easy. Here is what you need:

    10mm, 12mm, 13mm wrenches
    Knife
    Rags
    Brake/TB/Carb Cleaner or other solvent
    Oil
    Lacquer Thinner


    Here is how to do it:

    loosen alternator (13mm and 12mm bolts on mine)

    remove four 10mm nuts holding fan assembly to water pump pulley

    remove fan assembly

    Remove four long 10mm bolts that hold fan to clutch (note the old oily dirt in center ring of plastic fan.

    Wash fan in soapy water (paint it if you feel spanky)

    Remove four short 10mm bolts from rear of fan clutch

    Use knife to pry front and back halves apart (they are stuck together with suction)

    Drain remaining "honey" oil inside

    Remove O-ring and recondition with lacquer thinner

    Clean/flush aluminum halves with brake cleaner or similar

    Refill back half with oil and a few cap-fulls of lacquer thinner.

    Reassemble

    Check for leaks

    Reinstall

    Check for leaks and proper operation

    Hope this helps you out.

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    Default

    Well, I can't find it.... I've gone through every issue of SportZ and ZCar magazine page by page for the second time and don't see it....so now, I don't know where I saw it....

    What ZMeCruise posted is pretty much what I was looking for, except the article I read told which viscosity oil was the best to use....
    "If it weren't for fools, the rest of us could not succeed." Mark Twain.

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    Default Re: Heres what I found

    Originally posted by ZmeFly

    Check for a seized fan clutch it by opening the hood with engine running in neutral.
    As if you'd open the hood with the engine running in gear?
    -Mike
    Add your Z to my online spreadsheet registry

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    Not strictly relevant here but I understand that the really early fan clutch ( that goes with the metal fan) cannot be rebuilt as it doesn't have 2 halves that are bolted together and therefore doesn't come apart.


    FWIW


    Andrew

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    What's the process for reconditioning an o-ring with lacquer thinner? Victor.

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    Default

    Just a little something to add to ZmeFly's excellant response. Before you go to the bother of dismantling, cleaning and re-assemblying the fan clutch, make sure that the shaft connecting the blade assembly to the clutch assembly is still tight.

    If your fan 'wobbles' (check only with the engine OFF!!) and is unusually noisy, even at idle, then the internal non-replaceable bearing is worn and the unit will need to be replaced. All the cleaning and oil replacement in the world won't make it work any better. Been there, done that .

    Cheers,
    Peter
    1972 240Z Resto almost finished
    1983 280ZX This winter's project

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    Default

    ZmeFly, thanks for the tutorial. I'll jerk the fan off my '78 parts car and see what I can do to rebuild it. If that goes well, I can swap it out with the problematic one on the running '78. I like $5 much more than the costs for the other solutions!
    Mark Brandyberry
    1970 240Z (11/69) HLS30 00215
    1978 280Z (05/78) HLS30 466356
    IZCC #802 & CZC#4028

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    Wish we could find out what viscosity of oil to use for this purpose. I'd think that there would be significant performance differences between the various multi-wieghts, and straight weight oils that could be chosen, especially if they are "watered down" with lacquer thinner.

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    Originally posted by Bambikiller240
    Wish we could find out what viscosity of oil to use for this purpose. I'd think that there would be significant performance differences between the various multi-wieghts, and straight weight oils that could be chosen, especially if they are "watered down" with lacquer thinner.
    Very true. Obviously, the "normal" fix for this is replacing the clutch. I have the factory manual and about 5 other manuals of various types on Z's, and NONE of them even gives a good diagnosis section for the fan cluch, much less how to repair it or any actual data on it. They all have the same very nice drawing, and a description of the theory of operation, but nothing else. Oh well, unless the real data surfaces, then using the wrong oil weight can't hurt it much, since it doesn't work anyway! Just a waste of time to rebuild if it doesn't work after...
    Mark Brandyberry
    1970 240Z (11/69) HLS30 00215
    1978 280Z (05/78) HLS30 466356
    IZCC #802 & CZC#4028

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    great post guys , getting ready to remove my electric fans that are horrible , got a fan/clutch from ebay , now I know how to rebuild before installing , well let you know how it goes , thanks Jeff P.S. anyone have much luck with the fan shround from msa? in florida here need all the cooling help I can get

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    I found a web page that describes a fan clutch rebuild and it gives a specific product (w/ part number) to use for the fluid in the fan clutch.

    Here's the Link to the Information

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    Default Ive seen that one

    Its from a toyota forum.

    I dont see where though you got the oil would be thinned out by laquer thinner???

    Its an old trick to add some life to worn or dried oring type gaskets to give them some life. You just give them a quick soak and clean in some laquer thinner.

    I wouldnt be putting it in my oil for the clutch fan.

    Most people that I know that have done the clutch fan rebuild usually use a 20/50 oil in the clutch fan.

    If you could contact Nissan maybe they have a specific oil that goes in there? Who knows

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    Default Re: Ive seen that one

    Originally posted by ZmeFly
    Its from a toyota forum.

    I dont see where though you got the oil would be thinned out by laquer thinner???

    Hi James:

    I quote from the instructions previously posted "Refill back half with oil and a few cap-fulls of lacquer thinner".

    I've also found on a Porsche forum a recommendation to use the same Toyota fluid for rebuilding 928 Fan clutches.

    RENN List

    For myself, I'd rather spend a few extra bucks and get something (Nissan or Toyota, or whatever brand) that was meant for the purpose, rather than trust me to mix up a home brew, that may or may not match the viscosity, and thermal charectoristics of the original fluid.

    Just my $.02
    Last edited by Bambikiller240; 12-03-2003 at 03:58 AM.

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    Originally posted by Bambikiller240
    I found a web page that describes a fan clutch rebuild and it gives a specific product (w/ part number) to use for the fluid in the fan clutch.

    Here's the Link to the Information
    The factory manual for my '78 mentions silicone oil, so the description in the link is consistent as well. Thanks for the link!
    Mark Brandyberry
    1970 240Z (11/69) HLS30 00215
    1978 280Z (05/78) HLS30 466356
    IZCC #802 & CZC#4028

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    Default Huh

    I didnt notice that, it is from anothe forum, hes a good member and has posted several good how to's and tutorials. Thats something that I missed.

    I surely wouldnt as I said before though put that in my oil irregaurdless.

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    Just a question

    Does the viscous coupling on the Z have the same bimetallic strip on as some fans or is a straight "dumb" coupling relying purely on the viscosity of the oil and not any form of temperature reaction

    I have seen both used on differant vehicles thats all (non Zeds)
    Quickest NA L6 engined Z in the UK 13.19@102.02 mph for the 1/4....on a non bored/stroked 2.8

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    Originally posted by SteveK
    Just a question

    Does the viscous coupling on the Z have the same bimetallic strip on as some fans or is a straight "dumb" coupling relying purely on the viscosity of the oil and not any form of temperature reaction

    I have seen both used on differant vehicles thats all (non Zeds)
    It uses a bimetallic coil that opens and closes oil passages depending upon temperature.
    Mark Brandyberry
    1970 240Z (11/69) HLS30 00215
    1978 280Z (05/78) HLS30 466356
    IZCC #802 & CZC#4028

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    The link provided says to use "50mL of 3000Cst. silicone fluid " to refill the clutch. Do they sell this stuff at autozone?
    Drive it like you stole it.

    '75 280Z (my baby)- '07 350Z (daily driver)- '86 944 Turbo (Track Car)

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    Originally posted by venom42
    Do they sell this stuff at autozone?

    I have not found any parts store that carries it. Use the part number provided and order it at your local Toyota Dealership.

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    I've been going through the same delima. I bought a Z afew months ago and the fan blade had about a 25% carve off I guess it came in contact with a radiator. I had a 75 parts car and I took the clutch and blade off and installed on the new Z. First of all the car ran like it just had an engine overhaul or something....fricken fantastic! And whole lot quieter because before it was making a sound that kinda made it sound like IRL car (I thought it was the muffler making the noise). Anyway, the car ran much better but I noticed that the temp guage creeping up on prolonged idles. So it turned out that the new clutch and fan that I put in was just the opposite in that it wasn't catching like it should. Even hot the fan spun freely. So I yanked it off again and did the 20/50 fill up (I didn't put the thinner) and I used a sythetic oil. I did this today but after a test drive the clutch still doesn't seem to be catching.

    The clutch and fan are pretty cumbersome on the water pump and can reek havock should they sheer off. I was so impressed with the power and noise reduction that now I'm wondering if going electric is such a sin?
    Shallow Ed's 76-280z

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    You can get electric fans off eBay for about the cost of a new fan clutch if I remember correctly.

    I have a spare set of fans off my parts car for the Talon, wonder if one of them would fit? Would you wire them directly to the battery (they have a thermostat on them)? I just do not know if I want to go that route though. I wanted to try and keep her pretty close to orginal.
    Last edited by venom42; 06-10-2004 at 06:57 PM.
    Drive it like you stole it.

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    I'm a little aprehensive about wheter the fan would be too much on the 30yr old electrical system. Is there somewhere on the radiator to install the sensor?......geeeez iduno if this is a good idea!
    Shallow Ed's 76-280z

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    I just want to add that the silicone oil needed when rehab-ing one of these fan clutches proves to be pretty easy to find at hobbyist stores where they sell radio-controlled cars. I just bought a 50-ml bottle, which is somewhat more than I needed, for $6.50 in the 3000 weight. 5000 and 10,000 are also commonly available. The 5000 might be preferable to the 3000, which seemed a little thin to me (although no thinner than 20-w-50). It is used in radio-control car differentials, so you might mention "diff oil" as well as "silicone."

    This compares pretty favorably to buying 3 of the 18-ml bottles from a Toyota dealer, particularly in that neither of my local dealers had any of the three weights in stock.

    This clutch behaves really nicely now.

    Steve.

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    I printed an article from the Atlantic Z Car Club that I have used while putting my Z back together. It is "Z Tech Tips - Fan Clutch Refresh. I just looked at their web page nd the article has been removed.The recomended oil in the article was GOO -any thick anti-smoke oil additive such as Lucas, STP, Bardahl, etc. The author also recommended using lacquer thinner to refresh the o-ring.
    Wally Dill
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