Black fuel filter(pics included)

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by nikmirbre, Aug 9, 2021.

  1. MLC Adventures

    MLC Adventures Medium Load Member

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    If you'd have done the fuel analysis, you'd have gotten the results already. No guesswork involved, and takes seconds.

    Still betting on combustion chamber gasses. Seen it many times. Oil cannot get into your fuel through injector o rings or cups, and while it's possible the fuel pump could, never seen it in 27 years of Detroit work.
     
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  3. nikmirbre

    nikmirbre Road Train Member

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    Youre probably right
     
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  4. nikmirbre

    nikmirbre Road Train Member

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    Combustion chamber gases= are you saying worn piston rings?
     
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  5. bad-luck

    bad-luck Road Train Member

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    Looks like oil in your fuel. Check you fuel tanks to see if they are discolored.
     
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  6. nikmirbre

    nikmirbre Road Train Member

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    Its a 12.7 there is virtually no place for that to happen. Tanks are clear and clean!
     
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  7. MLC Adventures

    MLC Adventures Medium Load Member

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    No. It is almost always minute amounts of gas getting into an injector from one of the injector tips not sealing off completely.

    Unlike a loose injector or bad injector o rings, where the amount of gasses affect driveability, the small amount getting into the fuel through a tip is rarely noticed until the fuel darkens.

    Don't just throw 2k into a set of injectors though. Do the fuel analysis first to verify the reason it's dark.
     
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  8. nikmirbre

    nikmirbre Road Train Member

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    Ok yes I was gonna say I don't exhibit any of the other symptoms of worn rings at all. Ive ordered a fuel test kit already from blackwater labs I think is the name of it....
     
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  9. bad-luck

    bad-luck Road Train Member

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    I never heard that it can't happen to a 12.7. It can happen to any diesel engine through the return fuel line to the tanks. It looks like oil to me, its possible you got bad fuel somewhere. I recommend you get your fuel analysis done, before you proceed any further.
     
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  10. nikmirbre

    nikmirbre Road Train Member

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    Ill take a picture of the fuel when I dump some out of the fuel filter.

    On a 12.7 there is no oil rail feeding the injectors. And there is a 1/2 inch gap between the fuel pump and air compressor with a spill port to the outside. Oil in fuel on a 12.7 just doesn't happen.

    The fuel looks like little bits of black soot(which I actually thought soot was thin and would dissolve) when I pour in a bottle.

    Ill take a picture either tonight or the morning..probably the morning lol
     
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  11. Rideandrepair

    Rideandrepair Road Train Member

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    I had the black fuel and pieces of fuel lines. Replaced the lines from tank to GT return valve. They were probably 15 yrs.old.
     
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