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Thread: Radiator Fan Question

  1. #1
    Join Date
    Nov 2010
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    Virginia
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    My Cars
    2009 E82 128i ZSP

    Radiator Fan Question

    I did multiple searches on this and was unable to find any answers.

    I have an 09 128i with about 899xx miles

    Stopped at the store today on my way home from work and once parked I noticed a little bit of smoke/steam/whatever coming from the front of the engine. Not a lot - but enough to make me look. It was also about 35 degrees (F) outside, but again, enough to make me look. Popped the hood, and the first thing I notice is that the fan was not spinning. No smoke or anything, but the fan was not spinning. The engine bay was not hat, I had no CEL and no other indicators of anything wrong.

    Went into the store for about half an hour, came out, popped the hood, started the car, and the fan was spinning.

    Honestly, the first thing I did was scratch my head and wonder if this was some sort of BMW thing that I didn't know about, but the more I think about it, the less I like it.

    Now I'm thinking that it may be a wiring issue or maybe the fan motor is starting to go?

    I will add that the belt blew up about six months ago and of course some of it got caught up in the fan, but it was still spinning with no issues.

    Any help is appreciated or if I missed some thread on this, please point me in the right direction.

    Thanks!
    2009 E82 128i ZSP, Space Grey
    2001 E46 330ci ZSP, Topaz Blue (Gone but not forgotten)
    1995 FZJ80 Toyota LandCruiser, White

  2. #2
    Join Date
    Nov 2010
    Location
    Virginia
    Posts
    12
    My Cars
    2009 E82 128i ZSP
    I got another reply in another forum:

    "Smoke was probably moisture evaporating off the Radiator, steam.
    The Cooling Fan doesn't run all the time, it's as needed.
    So long as the car is maintaining temperatures, you're fine. And it'll throw a light if it's not."

    Seems legit. Anyone else?
    2009 E82 128i ZSP, Space Grey
    2001 E46 330ci ZSP, Topaz Blue (Gone but not forgotten)
    1995 FZJ80 Toyota LandCruiser, White

  3. #3
    Join Date
    Jul 2011
    Location
    Arlington, VA
    Posts
    5,713
    My Cars
    2018 BMW M240i
    The fan’s operation is controlled by the engine computer (DME). The fan has power at all times, even when the ignition is off. If you look closely at the fan’s wiring you’ll see 3 wires. One wire (brown) is the ground. The other wires that’s the same gauge as the ground wire is 12VDC. The third wire is much smaller in diameter. That’s the wire that’s connected to the DME. The DME controls the fan by “pulse width modulation.” That is, the DME sends the fan controller signals (pulses) of varying duration. The DME tests the fan atvevery start up. Pop the hood and have someone start the car. Observe the operation if the fan. It should spin for a few seconds at about 20% if its top speed.

    Now, I’d definitely check the coolant level.

  4. #4
    Join Date
    Nov 2010
    Location
    Virginia
    Posts
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    My Cars
    2009 E82 128i ZSP
    Quote Originally Posted by MarcoZandrini View Post
    The fanís operation is controlled by the engine computer (DME). The fan has power at all times, even when the ignition is off. If you look closely at the fanís wiring youíll see 3 wires. One wire (brown) is the ground. The other wires thatís the same gauge as the ground wire is 12VDC. The third wire is much smaller in diameter. Thatís the wire thatís connected to the DME. The DME controls the fan by ďpulse width modulation.Ē That is, the DME sends the fan controller signals (pulses) of varying duration. The DME tests the fan atvevery start up. Pop the hood and have someone start the car. Observe the operation if the fan. It should spin for a few seconds at about 20% if its top speed.

    Now, Iíd definitely check the coolant level.
    Awesome and thank you! This is great info!
    2009 E82 128i ZSP, Space Grey
    2001 E46 330ci ZSP, Topaz Blue (Gone but not forgotten)
    1995 FZJ80 Toyota LandCruiser, White

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