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Thread: 'lectric fan?

  1. #1
    Join Date
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    'lectric fan?

    OK, I've seen a lot of reference to replacing the stock belt driven fan with an electric. My questions are WHY and HOW? I'm a dunce when it comes to electrical systems (and plenty of other things- just check my previous posts or ask my wife) is this a relatively easy swap? I assume that there has to be a thermostat and switch to start and stop the fan... But my real question is this: why do it in the first place?
    Jayhawk

  2. #2
    Join Date
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    a lot of guys like the electric fan cause the engine will spin freely..it will actualy add more hp on the engine if you take the original belt fan off.

    there is so many ways to do it. you can make a switch. hook it to the thermostat thing..do it that it is running all the time..

    i like it beter with electric fan..

  3. #3
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    May 2009
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    bmw 325i

    Post

    id like to know too,,, and how hard is the conversion from belt to electric fan?

  4. #4
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    More power! That's why. I found that it made a noticeable difference.

    I just wired a toggle switch to control the fan. I don't have the stock thermoswitch anymore so using it wasn't an option. My switch just closes the stock fan circuit where the thermoswitch in the radiator would have. If you keep the thermo switch you can wire up an OR circuit so you can manually turn it on or if you forget the it comes on when the thermoswitch closes

    as to how hard: you have to remove the stock fan (easy), remove the radiator (easy), install the fan (easy), put it all back and do the above wiring. I should also point out that I don't have AC so there is plenty of room in front of the radiator for my fan
    Last edited by txmatt; 11-14-2009 at 11:28 AM.

  5. #5
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    Quote Originally Posted by charbel View Post
    a lot of guys like the electric fan cause the engine will spin freely..it will actualy add more hp on the engine if you take the original belt fan off.

    there is so many ways to do it. you can make a switch. hook it to the thermostat thing..do it that it is running all the time..

    i like it beter with electric fan..
    So the electric fan would be mounted in FRONT of the radiator? I haven't taken out the one that's there for the A/C yet (met a guy at the SoCal Vintage meet that has installed a Sanden compressor to make the original A/C system work again, and I'm considering that before I pull ALL of the A/C stuff out). Would that fan, if it's running all the time do the trick?
    Jayhawk

  6. #6
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    I think the 16" fans from summit can be used on either side of the Rad (in the front they'd replace the stock high heat fan). If you run it all the time that'd be fine but in the winter it would take longer to get up to operating temperature which is not so great. You could wire it to a switch that is interrupted by the ignition so that in the on position the fan is on while the car is on and in the off position the fan is off all the time, then just turn it on in the summer and turn it off in the winter.

    Milo

  7. #7
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    but how much hp or drag are we talking about here? not that i think its a bad idea (my a/c is gutted anyway) but is it worth the cost?

  8. #8
    Join Date
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    Eugene, OR USA
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    '81 323i, 97 540i
    The conversion is very straightforward. I have a spare electric fan with harness, adjustable thermostat and new mounting kit available. If someone wants it, let me know and I'll PM pix.

    4 cyl cars should have plenty of room to mount the fan behind the rad. 6 cyl cars pretty much require the fan be mounted in front - for lack of space.

    In either case, we're talking about a small power gain. Should be noticeable on the dyno, but in terms of feel on the road... well, we're all optimists, right?

    In my view, the real advantage is greater control over fan operation, which is advantageous with a marginal cooling capacity to begin with. ...and things are a bit cleaner under the hood.

    Blair
    Eugene, Oregon

  9. #9
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    Fan harness is universal so the new fan plugs in where prior Aux fan was and is controlled by existing thermostat.
    See thread:
    http://forums.bimmerforums.com/forum....php?t=1293279
    Last edited by pommeree; 11-14-2009 at 03:11 PM.
    Eric P.

  10. #10
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    Hey'a Eric,

    My 323i came with an engine driven fan only - no 'lectric fan [primary or aux...] Anyway, the setup I have is a Hayden fan and it comes with everything needed to install on a car with no previous electric fan.

    FWIW...

    Best,
    Blair in Oregon

    Blair
    Eugene, Oregon

  11. #11
    Join Date
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    I'm reviving this thread from the dead. I am also thinking about removing the belt driven fan and going electric. Mostly because I think the engine should be quieter, and make a little more power. I have never done anything like this before.
    Is there a kit or can anyone recommend components they like?
    Last edited by typhoon320i; 09-12-2018 at 09:27 PM.
    My Car Blog:
    http://motoluvr.blogspot.com

    My current cars:
    '16 Fiat 500e (electric)
    '92 Honda accord
    '05 Scion xB
    '81 BMW 320i
    '12 Toyota Prius

  12. #12
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    I dont know if this is all E21's but I have an e-fan setup and I am using the e21's internal wiring for the auxiliary fan, which wasnt used in my e21. The aux fan relay, the temp switch on the radiator, fuse 13 and 11, etc. The auxiliary fan is powered directly to fuse 13 under the fuse box.

    Very simple set up. I overcooked it once trying to do a 2 speed fan setup with the volvo relay and its just not necessary. Someone can say otherwise...


    edit: I did pick up an E36 radiator for my M42 swap and used this switch. https://www.ebay.com/itm/M14-14mm-Ra...72.m2749.l2649

    Not 100% when the e21 temp switch opens but this opens just before the thermostat opens. A bit early but its what I found in a pinch, works well.

    edit 2: It's all laid out in the ETM, page 4-7.
    Last edited by jaredmac11; 09-12-2018 at 10:13 PM.

  13. #13
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    I use a electric fan for a few reasons. More power is not the main reason but welcome. The engine runs without the the bladetype fan much more silent. When placing the temperatur switch near the upper outlet the electric fan runs for a short while after switching of the ignition when the car is very hot. It then pushes so much heat out of the engine bay that i was really surprised about that.20180729_142240.jpgIMG_1334.JPG
    “Speed has never killed anyone. Suddenly becoming stationary, that's what gets you.”

  14. #14
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    So your e-fan is powered when the ignition is off?

  15. #15
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    Just out of curiousity, does every e21 have the wiring for an aux fan? Is it used for other components? I know the AC compressor is tied to the circuit

  16. #16
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    Only on cars that have A/C installed. it was designed to run continually when the A/C was turned on, in order to keep air flow through the condenser.

  17. #17
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    Hi, my fan is working without the ignition on to cool the engine down after shutting it up. It has been said:´´ 4 cyl cars should have plenty of room to mount the fan behind the rad.`` In my opinion it is not such an easy change. Going with the the wider and in my case thicker three row autotransrad requires the shorter 2002 m10 waterpump and waterpump pulley. There not enough space to mount an electric fan thicker than a little about 2" ! Andreas
    “Speed has never killed anyone. Suddenly becoming stationary, that's what gets you.”

  18. #18
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    Con
    it is quite difficult for the standard four cylinder fan to fail whereas any electrical might do so at the most inconvinient time

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