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3 colors of smoke...help

Discussion in '1982-Present GM Diesel' started by muddybuddy, Apr 2, 2007.

  1. muddybuddy

    muddybuddy 3/4 ton status

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    hey guys, on start up i have three colors of smoke: black, blue, and a little white (maybe from the blue?). this weekend chris (big94gmc) was driving behind me and said that he could smell unburned diesel. i imagine that has something to do with at least one color of smoke:doah:. what could be causing this? valve seals? heads? head gasket? im away from the truck now, but next time im around it, ive got plenty of work to do, and would like to get this fixed before its too late (hopefully its not already:o ) thanks guys
     
  2. longbedder

    longbedder 1/2 ton status Premium Member

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    Black is unburned diesel - no real harm in it (and you'll naturally have some left over from cranking). based on what your buddy said, your fuel setting may be a little high and you could probably back off the adjustment screw 1/8-turn. The only real good way to set your fuel is with a pyro guage - your EGT should max out around 1050 degrees Fahrenheit under load. Too high of a fuel setting could get the EGT above 1100 degrees and that would be bad. Other than that, black smoke is just wasted fuel and not really harmful.

    If the blue/white smoke go away after a couple seconds, it's probably no big deal. You may want to check your glowplugs - a couple of them not working is a common cause of startup smoke.
     
  3. muddybuddy

    muddybuddy 3/4 ton status

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    well i need to get some gauges (i just have dummie lights), and a egt gauge is on the list to get. where do i adjust the fuel setting? so if its set to high could that be wasting fuel and killing mpg? what kind of bad things result from the fuel being turned up? thanks
     
  4. longbedder

    longbedder 1/2 ton status Premium Member

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    Having the fuel turned up hurts nothing but your wallet as long as the EGT's don't get too high. Some people do it on purpose to make a smoke show :rolleyes: .

    I say it'll hurt your wallet because if it doesn't get burned, it's not making power (waste).

    Diesels aren't affected by richness/leanness the way gassers are. The only thing that matters in this conversation is EGT. Set that fuel screw so the max EGT is 1000 going up a hill with a load. That leaves a 100 degree margin of safety - a few seconds at 1100 degrees and you'll start to melt stuff. You can read how to do it here - go to page 14: http://www.bankspower.com/OwnersManuals/96291.pdf
     
  5. muddybuddy

    muddybuddy 3/4 ton status

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    cool thanks a bunch! also, ive got a complete gm8 turbo setup and plan to put it on this summer (hopefully). with the turbo on it, will the fuel have to be turned up or will it just remain the same? i see youve got a banks setup on your truck, how do you like that?
     
  6. longbedder

    longbedder 1/2 ton status Premium Member

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    I love it. It really wakes up the 6.2 quite a bit. Any naturally aspirated diesel will be lackadaisical - ya gots ta have the turbo.

    If you started with a stock, naturally aspirated 6.2 and put a turbo on it, you would want to turn up the fuel. It sounds like your fuel setting is already high though. That being the case you might not have to turn it up from where it is - the only real way to know if it's right (with or without turbo) is to have that pyro gauge.
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    It's normal to get black smoke on acceleration, turbo or not. I doubt it's been turned up any.

    Bluish/white is common when the truck is cold. If it smokes bluish/white for longer than 30 seconds or so after you start it it could be a sign your IP or injectors are in need of a rebuild. My Jimmy got to the point where it smokes like a train and pretty much wouldn't clear up. Very poor injector spray (big droplets instead of a fine mist).

    I got the injectors and IP rebuilt and the smoke issue was gone.

    Rene
     
  8. muddybuddy

    muddybuddy 3/4 ton status

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    alright thanks for the info. he said it was something to read up about. thanks for clearing it up, im still learning about this whole diesel thing :)
     
  9. mstockton

    mstockton Registered Member

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    It all depends on where the gauge is mounted, but the 6.2 was not designed for that high of heat, heck it wasn't even designed for turbocharging. I've heard some people running them at 1300 for extended periods, but more often than not, that kind of use will cook the sucker from the inside out...
     
  10. muddybuddy

    muddybuddy 3/4 ton status

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    if mine blows up, in goes a 6.5TD thats for sure ;)
     

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