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Thread: Fan clutch

  1. #1
    Join Date
    Apr 2009
    Location
    Houston
    Posts
    95

    Default Fan clutch

    I bought a non thermal fan clutch on therefommendation of the parts counter guy. Did I screw up?

  2. #2
    Join Date
    Feb 2009
    Posts
    19

    Default

    I like thermal clutches, and disagree with your counter man. Since they disengage, they are quieter and save more fuel...but they're more expensive initially. Here's what the Hayden website says about the two types:


    Non-Thermal Fan Clutch:

    Low cost alternative for some standard thermal clutches.
    Always engaged, less fuel savings than a thermal clutch.
    Spins at about 30-60% of the water pump speed.
    Shorter life expectancy.
    Cannot replace a heavy-duty clutch.
    Identified by the smooth, steel faceplate, (without a thermal spring assembly), on the front.


    Thermal Fan Clutch:

    Varies the fan speed with temperature of the air behind the radiator.
    Engaged (high speed) operation provides maximum cooling.
    Disengaged (low speed) operation provides fuel savings and noise reduction.
    Greater life expectancy than a non-thermal clutch.
    Briefly engaged at cold start-up.
    Engages at about 170 radiator air temperature, (about 30 lower than coolant temperature).

  3. #3
    Join Date
    Jul 2009
    Posts
    18

    Default

    I have a thermal clutch on mine and I was wondering how to tell when the clutch goes bad. If it is fully locked at elevated temperatures do you shoot the speed of it with a photo tach?

  4. #4
    Join Date
    Feb 2009
    Location
    Aiken, SC
    Posts
    2,423

    Default

    On a hot day, with a hot engine, stop the engine and turn the fan by hand. If it isn't hard to turn, it's shot. The ONLY time you can tell is when it is hot inside the engine compartment.

    Remember that the fan is only for low speed and idling situations. Above 30 mph, there is enough air flow that the fan is not needed.
    Allan E.
    Curmudgeon Extraordinaire
    Charter Member, Old Hippie IH Club
    Old fashioned binder freak

  5. #5
    Join Date
    Apr 2009
    Location
    Houston
    Posts
    95

    Default should i replace it with a themal

    Quote Originally Posted by JimKoz View Post
    I like thermal clutches, and disagree with your counter man. Since they disengage, they are quieter and save more fuel...but they're more expensive initially. Here's what the Hayden website says about the two types:


    Non-Thermal Fan Clutch:

    Low cost alternative for some standard thermal clutches.
    Always engaged, less fuel savings than a thermal clutch.
    Spins at about 30-60% of the water pump speed.
    Shorter life expectancy.
    Cannot replace a heavy-duty clutch.
    Identified by the smooth, steel faceplate, (without a thermal spring assembly), on the front.


    Thermal Fan Clutch:

    Varies the fan speed with temperature of the air behind the radiator.
    Engaged (high speed) operation provides maximum cooling.
    Disengaged (low speed) operation provides fuel savings and noise reduction.
    Greater life expectancy than a non-thermal clutch.
    Briefly engaged at cold start-up.
    Engages at about 170 radiator air temperature, (about 30 lower than coolant temperature).
    So should I replace the thing? I haven't had an overheating issue before but now I am running a/c that just doesn't keep up with the heat so I want whatever pulls the most air over the condenser and radiator as possible.

    Will the thermal actually pull more air? I can't find a definitive answer any where. Would it be advantageous to arrange an electric pusher fan with a thermal switch in front of the condenser and radiator?

  6. #6
    Join Date
    Feb 2009
    Posts
    19

    Default

    I'm pretty certain that thermal clutches don't slip very much when they're engaged. I think they turn at about 90% of their pulley RPM, which is quite a bit more than non-thermal clutches, which would definitely move more air. I doubt that you'll do better with an electric fan setup. If you want good A/C performance, a 7-blade fan and heavy-duty thermal clutch, along with a good-fitting fan shroud are hard to beat.

  7. #7
    Join Date
    Feb 2009
    Location
    Aiken, SC
    Posts
    2,423

    Default

    I have to disagree here. Electric fans can be set up to move a much larger volume of air. The key is in how you do it.

    On a mechanical fan, you are dependent on the condition of the fan shroud to direct the air flow through the radiator and not simply around the fan from the engine compartment. This creates a need for a clearance space around the shroud so you don't break something when you flex.

    An electric fan can be installed with a higher CFM rating, and it can be installed so that there is zero air gap around it. You can mount it very close to the radiator.

    One of the issues you will find with air conditioning condensors is that they also need to be "gasketed" so that the air must flow through them when the radiator is getting air pushed or pulled through. You don't want the air to go around the condensor, either.

    There are several ways to accomplish all of this. All of them involve some fabrication. One of the more common alterations on a Scout is the Ford Taurus fan. You have to set up relay interfaces, because it pulls some serious current. I have also seen other electric fans modified for the same use.

    The bottom line is simply how many CFM can you direct through the radiator. High speed electric fans use less horsepower and push more air. That does not make them better. You still have to install them in such a way as to take advantage of it.
    Allan E.
    Curmudgeon Extraordinaire
    Charter Member, Old Hippie IH Club
    Old fashioned binder freak

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