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diesel fuel in CAT engine oil at 11.6% dilution why?

Discussion in 'Shop Talk' started by parttimefarmer, Apr 19, 2015.

  1. parttimefarmer

    parttimefarmer Active Member

    Joined:
    Apr 19, 2015
    Messages:
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    Location:
    minnesota
    Have a CAT, a old D3C dozer with 3204 NA diesel engine.
    Engine has 2736 hours on it.
    The dozer is not used much, last time I changed oil was 9 years ago 2006, just changed the oil at 146 hours on oil over nine years.
    Took a CAT SOS oil sample received back the results.
    All wear metals analysis, infrared analysis were OK.
    The Physical tests showed fuel dilution.
    Report communicated; This oil sample tested at 11.6% fuel dilution.
    This fuel dilution problem requires immediate attention to determine cause and prevent possible engine damage.
    I get it, some thing is wrong.
    But with only 2736 hours on engine what could be wrong?
    How could fuel get into the engine oil?
    As I am not a diesel mechanic; can you help with explanation, and what could be the cause.
    Thank you.
     
  2. lantraxco

    lantraxco Senior Member

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    One thing I would suspect is the injection pump shaft seal. Is there a separate lift or transfer pump mounted on the engine block on that engine? That would also spill fuel into the oil if there is one and it's leaking. Oh, and pop the valve cover off, I think that engine has jumper lines from bulkhead fittings to the injectors? I've seen those leak. Fire it up at idle with the cover off, don't get close but look for leakage or spray. Use a piece of cardboard or card stock if you need to check for spray, getting diesel injected into your hand or face or eye (OOOWWWW!!!) is horrible and possibly fatal.

    By the way, years ago we had a 3208 in a dump truck where I worked, one of the jumper lines came loose and filled the pan with diesel... when there got to be enough to suck in through the intake through the crankcase vent hose, the raw fuel and engine oil made her run away. Driver said it pegged the tach, and even with it in gear and driving through the clutch, ran away long enough for one of the rods to resign and part company with the crankshaft.
     
  3. overworked

    overworked Senior Member

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    I would change the oil and filter and run it 20 hours and retest. After 9 years I would not get really crazy off the start.could be a injector with a slooooow drip.
     
  4. SchuLace

    SchuLace Well-Known Member

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    USA
    I'm not sure about that engine but could injector o rings be a culprit?
     
  5. lake side bob

    lake side bob Well-Known Member

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    Location:
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    I went to the CAT dealer and spoke with a "tech" he informed me he would not be concerned, over 9 years an injector may be dripping a little and it built up.
    Said run it for a few hours more then 10-20 hours and take a oil sample.
    That's what I think you should do.
     
  6. nowing75

    nowing75 Senior Member

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    coatesville indiana
    resign and part company with the crankshaft. I like that one. Reminds me of years ago I think Harry gant said that the engine started making pieces on the back stretch.
     
  7. parttimefarmer

    parttimefarmer Active Member

    Joined:
    Apr 19, 2015
    Messages:
    34
    Location:
    minnesota
    Nowing75 what do you mean to communicate??? the engine is shot? or what?
    Please explain.
    The photo on your name; I take it that you are a heavy equipment mechanic, so I am interested in your ideas.
     
  8. Delmer

    Delmer Senior Member

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    Neither Nowing or Lantraxco were referring to your engine specifically. Just what could happen if you get too much diesel in the oil.

    If it was me, I'd run it and recheck the oil level every hour, and send a sample after 10. With 10% fuel in the old oil, and not getting all the old oil out at the oil change, there will still be some contamination, but I'd expect less than 1%.