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engine temperature trouble.

Discussion in '1982-Present GM Diesel' started by colbystephens, Nov 14, 2006.

  1. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    so i went wheeling the other day and absolutely could not keep the temperature of the engine more than a mm above the 100* mark, so i figure bad thermostat. i replace the thermostat and the engine warms right up. i think great... look down at my thermostat again and the temp has shot up above the 210* mark, so i turn on the heater and it is barely able to keep it averaging just a tick above the 210* mark (which means it fluctuates between 210* and maybe 1/2 way to the next tick mark up). so i figure maybe i missed something and put it in backwards. pull it out, and sure enough the spring side of the tstat is facing the engine, so i put it back in, hoping this was just a freak incident. drive to school again today and it does better - doesn't really need the heater's help to keep the temp at 210* except for about 3 or 4 cumulative minutes of assistance from the heater. do they just need a bit of time to set, or is this a bad tstat? i'm getting really sick of buying bad parts these days... probably over $100 spent in bad parts this last month. :crazy: anyone have any thoughts?
     
  2. imiceman44

    imiceman44 1 ton status

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    What is the temp range of the T stat?
    Usualy it will stay a little above that so if you got a 195 it will stay at 205-210.
    Also did you flush your system before putting the T stat on?
    If some rust or something got stuck in it it screws it up until it gets dislodged.
     
  3. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    the engine was rebuilt 5k ago, so i didn't flush the system. the tstat is a 195* stat, so i don't know what else to think...
     
  4. imiceman44

    imiceman44 1 ton status

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    I know your engine was rebuilt, I followed your build, but did you clean the radiator?
    Like I thought your Tstat is 195 so you will always be in the 200-210 range.
    :D
     
  5. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    i didn't clean the radiator. maybe i'll just try another tstat - they're only 7 bux. it's frustrating tho. i really romped on it last night to see what it would do, and ofcourse it went way above 210. just concerns me b/c of the mountains i gotta drive over to go to az this winter... guess i'll just try a second one.
     
  6. imiceman44

    imiceman44 1 ton status

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    This all started because you didn't have a T stat and you were not getting up to operating temps right?
    so you don;t have a problem with the cooling.?
     
  7. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    the tstat i had must have been broken, b/c unless the engine was running at high rpm for a considerable period of time, it was running really cold. i went wheeling the other day and my engine was just extremely cold the whole time except on the highway, with no heater running, i could get the temperature up to about the first quarter mark... speaking of the marks, how are the supposed to be read? it's not a linear scale - it starts at 100*, then a quarter of the way up it's got no numerical value, then another 1/4 of the way up, it's 210, then another dimensionless 1/4 mark, then 260... is the first quarter mark simply 155?
     
  8. imiceman44

    imiceman44 1 ton status

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    The way I use it if it's around the 210 I am fine, too low and it's too cold, when it get's past the point of 3/4 I start worrying about overheating.
    :D
    No real need to know exact numbers.:wink1:
    As for the graduation, it's very hard to do a mechanical guage that is linear, it's always going to be exponential.
     
  9. savagek5diesel

    savagek5diesel 1/2 ton status

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    first off.... factory temp. gauge isn't all that accurate so you can't rely on it too much. Second, i had a similar problem when changing my t-stat recently. Bought mine at autozone...... well autozone doesn't realize the 6.2 has a larger t-stat than a 350, so it gives you the same part# as the 350. mine kept over heating and doing weird ****. So i went to napa and got another t-stat and it was ALOT bigger compared to "the zones". So compare your old t-stat to the new one. Also i've heard the 6.2 is finicky if you mess with diff. t-stats opening temps, supposed to use the same one that it came with out of the factory or it wont heat up right, then the truck doesn't burn fuel efficiently or something of that matter. Good luck!
    p.s. do flush your cooling system, it'll help.
     
  10. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    good tip on the 350/6.2 tstat. i did notice a different size, but i figured it's like oil filters - one brand makes it different from another. :)
     
  11. savagek5diesel

    savagek5diesel 1/2 ton status

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    yeah, the 6.2 needs that larger tstat, wont flow like it should with the tstat missing or that 350 one in it. (I tried running my truck without a tstat and it would never warm up, or atleast the temp gauge didn't work without it in)
     

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