Oily fluid around DEF tank and in harness KW

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by skellr, Oct 25, 2021.

  1. skellr

    skellr Road Train Member

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    Screenshot_20211025-030736-483.png Screenshot_20211025-030817-424.png
    2020 KW T880
    Where is this stuff coming from? It doesn't smell like brake fluid or of amonia like def fluid. Its more like 10w.

    The backside of the def tank is coated with it and it's dripping from the wiring harness on the other side of the driveline.

    There is an intermittent derate with a red light in the DEF guage. I'm guessing this is just a short in the wiring from the fluid. It has progressed in to a "SCR system fault" and a check engine lite.

    It's at the dealer now. I'm just curious what the oily substance is and where it's coming from. How is it traveling through the harness shielding and over the driveline, and which direction?

    What the?
     
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  3. Goodysnap

    Goodysnap Road Train Member

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    Sure looks like engine oil to me. Big question is....where did it come from? Leak and the lights might not be related. Keep us informed. Id guess u have a bad DEF Q sensor on such a new truck.
     
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  4. Ffx95

    Ffx95 Road Train Member

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    That def quality sensor is at least a weeks wait if you’re lucky because of the parts shortage.
     
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  5. skellr

    skellr Road Train Member

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    The odd thing is the oil is clean looking, almost clear. I knew I forgot something.

    Screenshot_20211025-131124.png

    Do DEF pumps have lubrication in them? It is/was a new pump a few weeks old.
     
  6. Goodysnap

    Goodysnap Road Train Member

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    The DEF pump and tank only holds DEF and engine coolant. Engine coolant flows thru the pump and the heating loop inside the tank. Coolant keeps the pump cool and thaws the DEF inside the tank when frozen.

    May have no choice but to clean it off and see when it comes back. Is inside of the tank clean with good DEF? ApU or anything else in proximity to the DEF tank? Trans oil? Looks a little black in the photos.
     
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  7. skellr

    skellr Road Train Member

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    Ahh, it's probably coolant coolant then.
    It is a coal truck, that might add some darkness to it. :)
     
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  8. Goodysnap

    Goodysnap Road Train Member

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    Your right....... I see the red tint in the last photo now that I zoom into it.
     
  9. skellr

    skellr Road Train Member

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    They replaced the def pump and reset a pressure sensor. The def pump was previously replaced maybe two months ago...

    There was still a leak. It was coming from a fitting for the def tank heater right below a worm gear hose clamp. Moving the hose clamp over the leak "fixed" it, for now...

    It looks like the point where the hoses run over the driveline are lower than where the end of the shielding near the def tank fittings are, so it was feeding from the tank and over to the other side.
     
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