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Overheating

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 79 K5, Feb 1, 2001.

  1. 79 K5

    79 K5 Registered Member

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    I've been having an overheating problem lately. Once I reach normal operating temperature, the Blazer gets REAL hot at idle. When I get moving on the road, the temp goes right back down. I've replaced the thermostat and flushed the radiator. I THINK the clutch fan is ok. I may just take out the thermostat until I find a fix. Anybody experienced the same prob.?

    I can't hit a trail without overheating! I have to stop every 100 yards and cool down unless I run the trail at 35 MPH (which is fun, but not good for the truck :o)

    Jesse
     
  2. Smitty

    Smitty 1/2 ton status

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    Sounds like a fan clutch problem. I'd say you aren't pulling enough air through the radiator at idle.

    Smitty
     
  3. Storm Trooper

    Storm Trooper 1/2 ton status GMOTM Winner

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    Dillon Colorado, Hang'in in the mountains. Renting
    I'm no pro but the the fan clutch sounds like the problem. It appears that when your not moving you don't have enough air flow thru the radiator. Some other things to check:
    Are the fins on the radiator ok or beat up from rocks etc?
    If you have an automatic trans, is the cooling lines tied into the rad and possibly overheating the coolant?
    Is the fan shroud, belts etc. in good shape?
    Their is a lot of things that can cause this, you just need to eliminate some of them and move on to the next. Good luck[​IMG]. I hope I helped.

    [​IMG]
    [​IMG]<font color=red> Ride'in High In My K5! [​IMG]
     
  4. HarryH3

    HarryH3 1 ton status Author

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    I don't think that taking out the thermostat will help your problem. If it's working properly, it is wide open anyway, since the engine is running hot. I agree that it sounds like either the clutch fan is not working correctly or your shroud is missing. Is the full fan shroud in place?

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  5. 79 K5

    79 K5 Registered Member

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    The idea with removing the thermostat is just to lengthen the amount of time it takes to get hot. If it's wide open all the time, it will take lonoger to heat up....right?
    Anyway, I'm replacing the fan soon... we'll see if that helps. The shroud is there... it's cracked alot, but's there. With the new fan comes some brand new duct tape for the shroud. Thanks for the replies. Keep em comin!

    Jesse
     
  6. HarryH3

    HarryH3 1 ton status Author

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    It may make a few seconds of difference, since the engine should me much cooler most of the time with no t-stat in place. But it's still going to get hot if there isn't enough air coming through the radiator. Once the engine gets to the temp that the t-stat normally opens, then it doesn't matter much whether it's there or not.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  7. Cmoe

    Cmoe 1/2 ton status

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    Check the radiator also.... try to see a flashlight thru the fins. Look inside the radiator and see if you have corotion inside? Do you have your fan shrould on?

    C'moe

    <font color=black>the blazer is "Back in Black"
     
  8. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Whatever you DO NOT get a flex cool fan. I saw a guy who had a first generation Blazer that had a fan blade go through the hood. I'll have to find the page but its get a pic of 3/4 of fan blade sticking out of his hood. Imagine if that blade decided to do that while you were doing some work on it while it was running.

    June 2001 - The Texas Sawz All masacre begins. Be afraid rust, be very afraid. [​IMG]
     
  9. Smitty

    Smitty 1/2 ton status

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    Watched a blade come off a flex fan once. Don't think I've stood inline with a rotating fan since then. Doesn't matter what type of fan, they can all fail.

    Smitty
     
  10. reddog64

    reddog64 1/2 ton status

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    You might try flushing your radiator and putting new antifreeze... My s-10 blazer I had did this... I flushed it out fro a few minutes and it solved teh problem... It also needed a new hose...
    Goo dluck!!!

    Um... yes officer I know it's too big...
     
  11. ragtop

    ragtop Registered Member

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    Had an '81 camaro and put a mild 454 in it. Was real hard to keep cool when sitting still but did ok when going over about 45. Was told not to do this but (I knew better) tried running without thermostat and it ran much hotter. Radiator guy told me that it was moving water through radiator too fast and didn't have time to cool down before reentering engine. I had radiator taken apart and cleaned, installed 160 degree Robertshaw high flow thermostat, used 7 blade factory 19 in. fan with heavy duty fan clutch, trimmed and reinstalled shroud with about 2/3 of fan into shroud (big block sets further forward than orig. small block), FlowCooler high flow water pump, and I can now sit in traffic on 95 degree day with A/C running and engine stays around 180 deg.

    Ragtop
     

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