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Doing it again Help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Batchman, Aug 19, 2002.

  1. Batchman

    Batchman Registered Member

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    Quick summary, New 3 core rad, Dual electric fans(both are working) 160 t-stat, Would not get over 200 degrees in 103 heat. Now the last 2 days only 99 degrees but the truck will get to the high side of 210 setting at idle. water pump seems to work fine also if I'm getting flow to the upper rad hose it means the t-stat is working right? I also have about 30/70 anti/water mix

    Like I said ran cool for 1 month now it's like before I fixed it?

    What could it be?
     
  2. YtseJam

    YtseJam 1/2 ton status

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    You said you have 2 electric fans? So you eliminated the clutch fan/ or any fan running off of the water pump?

    Are the fans externally or internally mounted?

    How many CFM are the fans rated at and do you have an adequate shroud. You need to have sufficient airflow across the radiator.

    Do you have A/C ? Check for leaves or debris between the radiator and condensor.
     
  3. SkulzNBonz

    SkulzNBonz 1/2 ton status

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    My truck started runnin' hot a couple of weeks ago (I'm in Ok. too), went out and bought a new t-stat, runs cooler than it ever did now.

    John
     
  4. Batchman

    Batchman Registered Member

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    If there is water flowing back thru the top rad hose then the t-stat should be openign right? also Its only one month old?
     
  5. SkulzNBonz

    SkulzNBonz 1/2 ton status

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    Yes, that's how it's suppose to work. Mine was working, just not very well. I had a rad. leak about six months ago, so I put some Aluma-seal in it, hoping to cure the leak. It didn't, so I put a new rad. and t-stat in. Worked o.k., but was still hittin' about 210 degrees before the t-stat would open. It started running a little hotter a couple weeks ago, and finally just got to be too hot for my liking. I did a good amount of engine mods this last weekend, so I threw in a new 180 degree t-stat while I was at it. I think I still had a small amount of Aluma-seal running through the system, which I think helped shorten the life of the thermostat. Hope that helps.

    John
     
  6. bckinblk

    bckinblk 1/2 ton status

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    I just had the same problem with my k-5 I tried everything new stat flushed rad and nothing helped so I bought a new waterpump and it wont run above 180degrees .I got an autozone lifetime waterpump for $23 and no more overheating .try replacing yours I bet it will fix it .good luck
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    When my t-stat got "sticky" the upper hose would collapse, which was a pretty easy thing to diagnose : )


    I'd *really* suspect the electric fans, if you aren't pulling enough air, you are going to have overheating problems...most aftermarket fans simply aren't up to the task, as has been proven here.
     
  8. Batchman

    Batchman Registered Member

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    The temp guage is correct as check with meat thermo and I can also tell when it gets over 200 the AC does not blow as cool? As per a vent thermo as well. The fans are staggered 19inch Crown Vic(5.0)puller and a 17 inch pusher on the A/c condenser. I can put the stock fan clutch back on? but I I don't think that is the problem? I ran it in over 103 degree heat with no problems changed nothing and now its geting hot only 92 degrees today and it got up to 210 at a stop light as soon as I get going it cools down. its not a power problem either I have a 30% overdrive pulley on the alt for volts at idle. I'm baffled only thing I have not changed is the water pump, and it seems good? Also I put the 16lbs cap cause that is what came stock and I have the brand new rad.

    I know I've repeated myself alot on this post I'm just looking for answers and all help is appericated

    Not trying to be agrumenative on the electric fans, but why would they work for a month then not be enough to cool it anymore?

    I think I'm going with the 23 dollar water pump it's my last hope(BEFORE A MYSTERIOUS FIRE)!!!!!!!!!!!!!!!!
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    I just wasn't sure of the electric fan ratings. If nothings changed then no, I wouldn't suspect the fans.

    I guess someone did have luck swapping water pumps, so I won't say that can't be your problem, it just doesn't seem to be a likely cause. However, with differences in water pump designs, even among Chevy, changing pumps may work, but not because the other one was defective.

    Typically overheating at idle is because the fan(s) aren't working, but with electrics, I assume you know they are on or you wouldn't mention it.

    I don't personally like the idea of a pusher/puller setup, unless the fans are staggered (which you say they are, just clarifying here)so that neither is fighting the other, IE, one on the drivers side of the radiator, and one on the passenger side. Not that this is your problem, but it may not be helping if they are "fighting" each other.

    If the t-stat was faulty, you'd most likely either see spikes (hot, cold, and so on) or it would just keep getting hotter until it started spewing steam. If the radiator was faulty, you should have problems on the freeway. Fans and coolant flow should be the only things that affect cooling at idle, but it sounds like that shouldn't have changed.

    I believe one other source of engine overheating is head gasket problems. I'm not certain on that one, but I'm sure someone can chime in.

    Typically nothing just "changes" like that, something must have failed in the system somewhere, but the possibilities are almost limitless...sorry I don't have anything concrete to put in front of you!
     
  10. txbluethunder

    txbluethunder 1/2 ton status

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    how is your alternator output? if you fans aren't getting enought power than the cfm they output will be dramatically reduced.
     
  11. bajaviking

    bajaviking 1/2 ton status

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    Yep, I had a bad head gasket once which caused the engine to overheat but mine would overheat when driving and cool down when in idle.
     
  12. Batchman

    Batchman Registered Member

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    I have a 30% overdrive pulley on the alt for volts at idle. I have tested at idle in gear with full load and getting over 14 volts. I really don't know think I'll try to put the third fan (original with shroud) back on before I go with water pump? Ok head gasket thing hwo do I check for that?
     
  13. Batchman

    Batchman Registered Member

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    I agree something did fail? Now to the 25 dollar question what how can I check the head gasket?
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Never had one fail!

    I'd imagine bubbling antifreeze, water in oil, weak compression on one or two adjoining cylinders, etc.
     

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