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Overheating, please help!!! UPDATED

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Jaguargt, May 2, 2003.

  1. Jaguargt

    Jaguargt Registered Member

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    i need your help, originally had a 6 cyl, but i swap the engine to a 350, with no t-stat, new water pump, cleaned radiator, no leaking head gaskets, but still overheating,i'm using the original 350 solid fan with 4 blades, with fan shroud, could be this the problem, or I need a radiator for a 350?, thanx. for your help.
     
  2. BlazerGuy

    BlazerGuy 3/4 ton status

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    Re: Overheating, please help!!!

    You need a 3-row radiator for a smallblock, or you could opt for the 4-row too. Check out Radiator.com for some prices, members get a discount there. Also you should run a thermostat, because without it the anti-freeze cannot stay in the radiator long enough to dissipate any heat before it goes back into the engine. So the cooling system can't work properly...I hoped that makes sense... /forums/images/graemlins/grin.gif
     
  3. BlazerGuy

    BlazerGuy 3/4 ton status

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  4. Jaguargt

    Jaguargt Registered Member

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    Re: Overheating, please help!!!

    thanx for your answers, i'll ad a t-stat, what specs should i look for in a new t-stat?, and should i change my 4 blades fan?, or just the Rad, and the t-stat?, thanx again.
     
  5. gravdigr

    gravdigr 1/2 ton status

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    Re: Overheating, please help!!!

    You can run a 29" 2 row radiator on a SB 350 with no probs if it's done right. I ran one on my chevelle for years, the trick is airflow. If you have enough airflow you are fine, this gets to be a problem with offroading as you are not doing 80mph up the highway like my chevelle. Also do you use ac? The condenser is in front of the rad which will cause more heat.

    Now my personal recommendation. If you offroad a lot get at least a 3 row. I run a 185 thermostat but my ride is carbureated and older, newer rides can use a 165 cap. Use a fan shroud and for gods sake ditch that piece of crap steel fan. For one thing it sucks way more hp than a fan should, and pulls very little air. I run a 5 blade high rate flex fan. It has a very aggressive angle and pulls a TON of air at low rpm. And at high rpm, which is usually hit when you are on the highway, the blades flatten out pulling less power from the motor as you have air flying through the radiator anyway.

    Hope this helps.

    EDIT: just saw you said you were not running a Tstat? Bad idea. A motor is designed to run at a certain temperature, running below that temp can effect power and performance. That is why in my above post I said I run a 186 tstat, but some of the newer fuel injected motors are designed to run cooler. If it is a normal cast iron block with cast heads and a carb 185 is good. One easy way to check your cooling system is to have a temp guage that shows the exact temp. If the engine temp ever goes more than 10 degrees over the thermostat temp for more than a few minutes your cooling is inadequate.
     
  6. BlazerWheels

    BlazerWheels 1/2 ton status

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    Re: Overheating, please help!!!

    Hey Gravdigr...FINALLY another Spaceballs fan!!! Nice Sig! /forums/images/graemlins/thumb.gif
     
  7. wrathORC

    wrathORC 1/2 ton status

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    Find yourself a 180° thermostat and a 16lb radiator cap. The thermostat will slow down the coolant and will open soon enough to regulate temperature. The 16lb cap will keep it from boiling.

    I have a 2-core radiator full of calcium (thank you, previous owner that bought a 2-core when it called for a 3-core and filled it with city water). It cools my truck. It used to cool it really well when I ran my stock fan (it'd lay down grass and sandblasted the underside of my truck). It barely gets the job done with my electric fan when I'm offroading. A new radiator is in my future.
     
  8. MudFlap

    MudFlap 1/2 ton status

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    Re: Overheating, please help!!!

    I thought that fuel injected engines run closer to 200. My 89 blazer runs about 185 and I used to have a 88 pickup that ran at 200.

    Trey
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Overheating, please help!!!

    Most GM vehicles run at 195* (actually about all GM's from at LEAST the 60's up) and most injected electric fan equipped vehicles don't turn a fan on until they hit around 220*.

    Lower on injected vehicles is more of a problem than on a carb, as if it's too cold, the thing will never go closed loop, but that seems to be very engine dependent, as some get away with 160's and some don't.

    If you are just looking for cooling, and not all out power, 195* is fine. A colder t-stat doesn't do you any good if the rest of your cooling system can't keep the coolant under the t-stats rated temp.
     
  10. wrathORC

    wrathORC 1/2 ton status

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    Re: Overheating, please help!!!

    160° is too cold.

    180° is mediocre.

    190° is just about right.

    The hotter an engine runs the more efficient. However, it's harder on fluids and horsepower wanes.

    Most electric fans turn on at 108°C or 226°F. Trust me, I know. I spent a good hour looking through a sensor book trying to find a thermal switch that grounds out at about 96° and just about every single one (except for a few Pontiacs) turned on at 108°C.

    If you've got a shoddy cooling system like mine, a sooner opening thermostat will keep it from overheating. Unlike a properly operating cooling system, it takes forever to drop 10°.

    Running 160° is pretty much pointless unless you're racing.

    Running a cold thermostat to offset a shoddy cooling system is like putting a bandaid on a broken leg. However, I don't have $180 to give Summit for a new aluminum radiator.
     

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