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running hot a themostat Qs...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by StageZ, Jan 29, 2002.

  1. StageZ

    StageZ Registered Member

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    I just built an engine for my 84 K5 and am still on my break in.... unfortunatly, she has a 400 crank and I cant check my timing to the point... I hooked up a vacuum gauge to the carb(brake booster) outlet an adjusted my timing to the highest point of vacuum... still runing hot... the upper radiator hose doesnt seem to be getting hot by the time the temp sensor tells me she is... there are no air bubbles confusing it. I am just about to swap the new one for another new one.... what could be causing this? would it be a bad idea to ditch the thermostat all together? I live in So Cal so it aint in snow or weather below 40... any ideas? everything in the engine I built and checked(plastigated-cleaned).... any suggestions? thanks in advance....
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Speaking solely on the thermostat necessity, no, you don't HAVE to have one, at least to test. Many other variables, but you can certainly remove it to see if the problem immediately goes away, at which point you can, with relative certainty, blame the thermostat.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  3. slider

    slider 1/2 ton status

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    When you pull the radiator cap off can you see coolant circurlating in the radiator? Have you tested your cap? If the cap is bad it will not allow the system to build pressure and it will run hotter. What condition is your radiator in? I bet your timing is off and this is your problem, get a new pointer or what ever to check your timing. Eight to ten degrees before tdc is fine. If it pins a little back it off a hair. Again how hot is it running? Anything from 180 to 210 is fine on a newer motor. When it goes above 210 time to get concerned. Also use a real temp gage to make sure you have a hot problem. The GM sending units leave alot to be desired. Thermostats also keep your motor from running too cool, they also help the motor warm up quicker. If your going to get a new thermostat get a Balanced thermostat, Various companies make the Moroso, Mildon, etc
     
  4. Itali83

    Itali83 1/2 ton status

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    I would have never believed it until I saw it on my own motor. The guy who did work on it before put the intake manifold gaskets on backwards. That was enough to hinder the flow of the water pump so with a thermostat in the motor, the motor would over heat. The thermostat would never open becuase the hot water couldn't circulate up to it in time. When I was doing tests, it would get very hot in the head and never open the thermostat. I probally would have been able to cook the motor if I kept it running. It never did any damage to my motor running it with no thermostat, it just ran cold, and I got it fixed and the motor runs perfect now. Just an idea since you were saying you just did some motor work.
    Ben 87 Jimmy
    <font color=blue>Rust=Bad</font color=blue>
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  5. hawglet

    hawglet 1/2 ton status

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    I run 160 during the spring through fall which is the same temps as your talking about and 195 during the winter. I'm running a 400 ci with a four core radiator. It seems to run about 170 to 180 all year long pretty much which keeps the heater nice but also provides a good operating tempature.



    Thanks, (in advance)
    Hawglet
    hawglet@excite.com
     
  6. Ovrtym

    Ovrtym Registered Member

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    A thermostat put in upside down might cause some issues.... just a thought [​IMG]
     

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