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Sludge In Oil That Does Not Mix With Oil

Discussion in 'General Industry Questions' started by Birken Vogt, Oct 14, 2020.

  1. Birken Vogt

    Birken Vogt Charter Member

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    This morning had one of the most mysterious jobs ever.

    It was to be a normal annual service on (air cooled 1.75 qts oil) generator. Arrived to find it had most recently locked itself out with a low oil pressure fault of which the customer was not aware. It had run 200 hours without anybody looking at it so this is not unusual at this point.

    Pulled the dipstick and found no oil on stick but a little bit of tar-like substance that took some effort to wipe clean. Added oil with about 50% of system capacity and it showed good enough on the stick to start. This is unusual because normally they have to get a lot lower than that to shut down on LOP.

    Engine cranked very slowly at first. Once it warmed up everything seemed normal. Customer did mention that it had been laboring during last major run.

    Drained oil and it was pretty black and drained slowly but looked otherwise normal coming out.

    The weirdness happened because after setting a while, this black sludge settled out with the oil on top and sludge on the bottom. The sludge resembled fine garden silt in texture. After pouring the oil off the top the sludge remained in the pan and you could draw a finger through it and it would stay clear of the bottom.

    After sitting the rest of the day all over the drain pan the rest of the oil had drained away and the sludge resembled chewing gum but not sticky. Peels right off everything. I got some between my fingers and smashed it real thin and washed it in the sink thinking it may have been sugar. But it made no effort to dissolve, it just stuck all over my hands. Reminds me of the thick grease from a Cat that has sat in the woods for 40 years. Or maybe pine tar but not sticky.

    Quantity of sludge was roughly 30-40% of drain oil. The longer it sits the more it separates and coagulates. IMG_20201013_170342916.jpg
     
  2. Welder Dave

    Welder Dave Senior Member

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    Mixing synthetic with conventional oil or using some kind of additive? Know a guy who had a repair shop and had a Ford gas truck in because it was down on power. Owner used synthetic oil but figured it was OK for 25,000kms. Pulled the valve covers and it looked like shredded rubber inside. Ran engine flush through it 3 times to get rid of all the crap.
     
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  3. mitch504

    mitch504 Senior Member

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    I can't see it being related, but, I just rebuilt a planetary wheel hub that had stuff like that in it. It had completely eaten the wheel bearings and lost it's oil. It had this sludge in it, and once it dried, it was hard and crunchy. It had Mystik gear oil in it for 20 years.
     
    Truck Shop likes this.
  4. funwithfuel

    funwithfuel Senior Member

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    A while back, we had a Volvo/Penta in a Gradall. It was shutting down due to low oil. We get out there and pull the stick, it was ok. Started it, no oil pressure after 10 seconds. Pulled the drain and nothing comes out. Stuck a screwdriver in the drain and pulled jelly. We pulled the pan and thought for sure we had a bad liner or head gasket. It was 100% gelled up. Let it sit overnight in the warm shop and the bottom 3" or so returned to oil. We thought sabotage after ruling out coolant intrusion. Oil sample said plane ol water was the sole contaminant. I posted pics up here, but I'm not a good search person. Perhaps, maybe, you're getting water in, through somewhere. With only 2 its, it wouldn't take much to compromise the quality.
     
    mg2361 and Truck Shop like this.
  5. Vetech63

    Vetech63 Senior Member

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    There is no telling what kind of oils or additives have been put in that engine. Ive seen a coolant leak into the oil do that like FWF said and more times than not it is 100% gelled up.
     
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  6. skata

    skata Senior Member

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    How often does the generator start up? Could be a moisture buildup issue from repeated starts and not warming up?
     
  7. Birken Vogt

    Birken Vogt Charter Member

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    These units do run a frustratingly short (5 min) exercise and they always have milky oil when we change them. But we have changed hundreds of them and never anything like this. Air cooled engine by the way and fuel is natural gas. Also this thing has run several long duration outages very recently and experience has shown that will normally burn the condensation right out of the oil.

    I am open to the idea that it is condensation, but skeptical. How could it be that it mixes with oil and then separates out again? Unless the water had some sort of chemical reaction with the oil.
     
    Truck Shop likes this.
  8. MarshallPowerGen

    MarshallPowerGen Well-Known Member

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    Generac I take it (with the 5min excercise time)? Anything strange under the valve covers, or any blockage in the crankcase vent? I take it the "sludge" didn't stick to a magnet?

    Had a lot of the coffee creamer jello molds under the valve covers up here, but don't recall anything like you're seeing.
     
  9. Birken Vogt

    Birken Vogt Charter Member

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    Did the overhead as part of the job. The oil that pools in the hex socket bolt heads resembled honey but no sludge up there to speak of. I think I know what you mean by Jello mold but that does not happen here, probably not cold enough. All we get is light condensation in the oil when draining, that was definitely not how this appeared, just dark brown or black.

    I would suspect sabotage since it is in a downtown location and loud, but it has locks that the customer keeps locked that were not damaged. The key is pretty common though but that is going a little far for a saboteur to sneak into someones completely visible back yard and mess with equipment right outside their house.
     
  10. Truck Shop

    Truck Shop Senior Member

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    Non detergent oil and synthetics don't do well, neighbors pressure washer with Honda engine.
    it was low on oil so he dumped some straight 30 wt non detergent in it to pressure wash his house
    then didn't use it for 4 months-it looked like tar. Just a guess.

    I do know Power Punch and 75x90 turns to goo in wheel ends on trailer axles and is a slime ball
    to clean up.
     
  11. Birken Vogt

    Birken Vogt Charter Member

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    The longer the globs sit in my drain pan the thicker and stickier they get. I think the oil is draining out of them and they are thickening up. They stick together pretty good but they peel off surfaces in one piece. My wife made brownies yesterday and these things behave like a sticky brownie in a pan. Work them gently and they act like a sticky blob, mash them up and they crumble for a bit. They seem somewhat granular in this condition. Water does not affect them but I put some on the bench with acetone. Acetone slowly dissolves them into brown liquid that thins out and spreads out. More to come, a lab may be in our future.
     
    Truck Shop likes this.
  12. Truck Shop

    Truck Shop Senior Member

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    At least with a lab test it would stop the guessing and know for sure.