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Fan Clutch-afaik the proper testing procedure

Discussion in 'E39 (1997-2003)' started by ViolinARC, Jul 8, 2011.

    ViolinARC guest

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    OK...if you start searching on this subject, you'll get several different versions of the "proper" way to test your fan clutch. My favorite was that you can't test your fan clutch unless you go to an automotive shop and the most stupid was to use your HAND for testing a spinning fan blade...RIGHT!!

    Anyway, from my research and q/a session with Derek, a tech at BimmerSpecialists, the proper troubleshooting procedure is:

    A: Engine COLD and running. Small amount of rolled newspaper (please...NOT your hand) should stop the spinning fan easily when applied. I just touch the tip of the paper to the tip of the fan blade because of the next test...

    B: Engine WARM/HOT and running. Same amount of rolled newpaper will NOT stop the fan from spinning as the clutch is engaged, which causes the fan to spin with the engine RPM from my understanding. Remember to only touch the tip of the paper to the tip of the blade!

    If you experience the opposite reaction in either of these tests, you probably have a bad fan clutch. Two other items mentioned are a wobbly fan (moving laterally), which could also indicate a faulty water pump and/or excessive noise, which was one of my symptoms.

    I hope this helps someone else and that the subject isn't viewed as stoopid...LOL! Anyway, I'm less confused about the subject for sure and welcome any additional info. Thanks for reading...

    DISCLAIMER: I assume no responsibility for the information given here nor for the failure to properly diagnose or repair your car. I'm just sharing information that I had to spend time digging up to hopefully save someone else the same effort. Peace...
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    The fan blades are known to

    The fan blades are known to become fragile on the E39-E38 V8's, typically around 100k, yes? Did whomever broke their fan blade with the newspaper test offer up the age and mileage? It's one thing if somebody broke a brand new, or, let's say... sub 75k-85k fan blade, vs a higher mileage. Anyone offer up any comment on whether it's age related vs. just mileage? Would a '95 or '97 V8 with low mileage (say, under 50k) still be susceptible to having the fan blade, radiator neck, or expansion tank failures just because of the age, or is it a running-time factor? Of course, any risk of having a piece of shrapnel flying off a fan blade towards oneself at high speed and risk of injury probably isn't worth taking the chance.

    ".... Hey, Ya'll!! Watch this!!", comes to mind! :-p

    ViolinARC guest

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    Yes, I do believe that the plastic fan is only slated for a limited life but mine appears to be very solid after 150k. I have had the opportunity to install and uninstall the fan clutch several times as I was testing the new vs. old unit so I inspected the fan very carefully for any signs of cracking or weakness. All seems to be well...'fingers crossed'!

    I didn't actually state that anyone had fractured their fan with a newspaper but rather had a tech express his "concern" at my placing the object to the tip of the spinning blades. Just to clarify...it's just as easy to apply the newpaper closer to the hub.

    As for the experiences of having the fan blade "explode", that seems to be related to an already cracked fan, the fan clutch seizing or a bad fan clutch allowing the fan to spin at high engine rpm's, which will cause the plastic fan to fracture and fail as well. I've seen what can happen under the hood because of someone sharing the info at bimmerforums.com and it ain't pretty!

    Anyway, I'm afraid to post much more info due to the fact that it appears management is looking into a different forum solution, which will probably mean ALL the new posts will also be lost to the internet ether...

    ViolinARC guest

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    Testing Procedure Revision and great link...

    OK so I've been told that the newspaper test as it was described to me could be dangerous. Do NOT put the newspaper to the tip of the fan blade as it could cause the blade to break (that was my idea but I take it back...LOL). Instead, try to place the rolled newspaper as close to the hub as possible and ONLY after the engine is at operating temp as described here.

    Here is a link to a very detailed procedure...

    I would edit my op but it doesn't appear to be an option so I guess I just have to look like an idiot...ARGH!

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