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Fan Clutch Too Powerful?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 87K54WD, Aug 15, 2001.

  1. 87K54WD

    87K54WD 1/2 ton status

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    I just bought a new fan clutch (Hayden Model 2797 "Severe Duty" for rear gears 3.73 and higher) for the K5. The truck really makes a roar now. I've got the SM465 so that is to be expected but seems almost like too much. I wondering if I will start to lose fuel economy, power, etc. They have the heavy duty version (Hayden Model 2747 for rear gears 3.42 and lower) but I wasn't too happy with the way it would bolt on to the pulley, which is why I got the severe duty one. I have 3.42 rear gears. Any ideas??? I'm thinking of taking it back and getting the heavy duty model instead. I must say though, it sure is keeping the truck cool. Truck stays right at 195 now even with the A/C on in stop n go traffic in close to 100 degree heat.
     
  2. 87K54WD

    87K54WD 1/2 ton status

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    Just wondering if anyone has any ideas on this. I was planning on doing this tonight after work. I figure the sooner I take the part back the less "kick back" I'll get about it.
     
  3. blazer72

    blazer72 1/2 ton status

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    Leave it on you can never get to much air though the front . what work is town to keep it cool may not be enough on the trail. Besides after it warms up it will slow down a bit
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    It really should "shut off" after you start it, after about 10 seconds or so. You DID get one with a bi-metallic coil on the front right? Thats the style you need...

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</a>
    No anti-theft measures on your truck? No pity when its stolen
     
  5. Itali83

    Itali83 1/2 ton status

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    You haven't heard noise until you have a solid flex fan like me. Can't beat it for cooling though. The gas mileage you loose has to be minimal.
    Ben 87 Jimmy
    <font color=blue>Rust=Bad</font color=blue>
    <a target="_blank" href=http://www.bens87toy.alloffroad.com>www.bens87toy.alloffroad.com</a>
     
  6. 87K54WD

    87K54WD 1/2 ton status

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    Yeah, I got the one with the bi-metallic coil on the front. It is weird because it really seems to roar when it is cold (in the morning) until it warms up and then it sort of drops off. It is still much louder than the stock unit. It's doing a great job!!! Just throws my shift points off now (SM465). I tend to shift when I hear the engine reach a certain noise level. By accident, I was still in 2nd gear at 47 mph this morning. For some reason it didn't seem very loud. Everything is different now. In the process, I started wondering how much power I was losing (if any) and fuel economy. I really don't understand why they ask about the rear gear ratio when buying their fan clutch. Any ideas?
     
  7. muddin4fun

    muddin4fun 3/4 ton status

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    I've got the flex fan too! I love it!!!


    It's been lovely, but I have to scream now.

    <a target="_blank" href=http://www.geocities.com/muddin4fun79blazer/>http://www.geocities.com/muddin4fun79blazer/</a>
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, the roar fromt eh fan when cold is normal. Pop the hood when it is cold, start it, and stand next to the fender. You should hear and feel the fan when it shuts off. Course it will still be spinning, but you should notice a huge decrease in air and noise when it does shut off.

    Still seems kind of odd that you can hear it when dricing though. Maybe my ears are spoiled from no interior, but even in my car, I can't hear the fan once its shut off.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</a>
    No anti-theft measures on your truck? No pity when its stolen
     
  9. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Yes, the Severe duty clutch is too much!!! I have been down this road a time or two and have learned not to buy that sever duty clutch. It sound like it never shuts off...right? Well it wont most of the time. Go buy the heavy duty one. It will work just fine...I am sure! If your radiator is dirty on the outside, it will not let enough air pass thru to trigger the clutch on a heavy duty model.
    My advice, get the heavy duty model, AND clean out radiator. Spray some degreaser and rinse very well with a garden hose, no nozzle. It will help out alot.

    My .02,
    John

    '83 GMC Jimmy 4x4 ZZ4 Crate Motor
    '83 Chevy K20 Sand Drag Racer, 578 RWHP
    '94 Impala SS
    '01 Chevy 2500HD 4x4 w/8.1L & Allison Auto
     
  10. old4x4

    old4x4 Registered Member

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    I found that the fan clutch didn'tnwork out to well so I swapped mine for the regular fan off my 79 with a 3 row core and it works just fine
     

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