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Over heating big-block

Discussion in 'The Garage' started by Snarly, Jul 21, 2003.

  1. Snarly

    Snarly Registered Member

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    I have a 454 in an '82 K5 with a 4-core radiator, electric fan, large K&N air filter, dual exaust, 4.56 ratio and 400 transmission. It runs very hot driving slow off-road. The anti freeze is a bit heavy rated at -30 but I'm in Colorado. Would it help to get rid of the cowl and clutch fan replacing them with a 19 inch steel flex fan?
     
  2. Sandman

    Sandman 3/4 ton status Author

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    See if the clutch on the fan is bad. I had overheating problems too. Went to a full shroud and other stuff and still overheated. Put in a new clutch for the fan and now there is no overheating at all. /forums/images/graemlins/grin.gif
     
  3. Snarly

    Snarly Registered Member

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    Good idea. What is the best way to test it? In addition, if I remove the cluch fan, must I replace it in exactly the same position? I've heard conflicting answers.
     
  4. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    There is about 4 posts going on about this same problem. Here is the one I have going on my 454 in my burb. I'm Overheating in traffic with the A/C on. Some good pointers have been posted.
     
  5. diesel4me

    diesel4me 1 ton status Premium Member

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    My 77 K20 4x4 plow truck would only go about 5 miles with the plow blade on it before overheating--I figured i toasted the thermostat,so i bought a new 195 degree one and went to put it in and suprise! no thermostat in it at all,and I know not having one can make engine run hotter because it lets the water rush through the radiator too fast and doesnt get cooled enough,so i put it in and then i could drive 8-10 miles and the same results--after asking everyone i know about overheating problems,the parts counterman at the local chevy dealer told me to "lock in" the fan clutch by lifting the spring in the center of the clutch out of its little holder and turn it 180 degrees and lock it back in the little holder thingy and voila!no more overheating even on the highway for as long as it takes to get to my destination! /forums/images/graemlins/thumb.gif /forums/images/graemlins/grin.gif :The fan will roar like a lion though,and it does cut down your gas mileage and power,but its better than frying a head gasket(mine is a small block 400,noted for cracking heads,cant beleive i havent wounded it by overheating it 10 times!).This was a service bulletin on the later trucks,but it works on all fan clutches(gm at least)that have the thermostatic spring in the center.Dont waste $$$on the cheap clutches without the spring,they are just a speed limiter and let the fan slip some all the time,ok for regular street cars,but nothing too demanding. /forums/images/graemlins/truck.gif /forums/images/graemlins/usaflag.gif /forums/images/graemlins/grin.gif
     

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