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Cat 299d2 3516-18 ACU Catalyst Reagent Concentration Low

Discussion in 'Skid Steers' started by Squishy, Nov 19, 2020.

  1. Squishy

    Squishy New Member

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    Fairly new machine with only a few hundred hours on it. It has been sitting for 3 months or so.
    Ran it today and got this yellow caution: 3516-18 ACU Catalyst Reagent Concentration Low
    The DEF tank show 3/4 full but I can't remember the last time I put any in there...does it go bad or lose active ingredients or something to that effect?
    Thanks for the help!
     
  2. Nige

    Nige Senior Member

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    Yes - It has a shelf life in the tank of around 3 months IIRC. Longer if stored in a sealed container.
    I would suggest to try flushing the tank and refill with new fluid. See attached. The DEF filter will also need replacing.
    From all the info circulating regarding engines using DEF leaving them parked for long periods is not the best thing one can do.
     

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  3. Squishy

    Squishy New Member

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    Thanks for the quick reply! Why do you think the filter needs replaced?
     
  4. Nige

    Nige Senior Member

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    Because the procedure I attached says so........... see Step 10. I'm not familar enough with the system to answer the question why this should be. Maybe someone else can help you regarding that.
     
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  5. Squishy

    Squishy New Member

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    OK. Thanks.
     
  6. Coaldust

    Coaldust Senior Member

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    The DEF can start to crystallize on the surface of the small filter. Plus, it’s easy to contaminate the DEF while filling the tank on the job site. Logical assumptions.

    Squishy,

    Not sure where you are located. It might be something as simple as a frozen DEF tank.
     
  7. Cmark

    Cmark Senior Member

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    also the DEF filter contains a plug which swells and cuts off the flow if it gets contaminated by hydrocarbons. Not sure if it is similarly affected by degraded DEF.
     
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  8. John C.

    John C. Senior Member

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    Why would the fault code say "Catalyst Reagent Concentration." What I seem to recall was that the catalyst part was in front of the DPT and the DEF was injected behind the DPT. Is there something different between the small machine systems than the large machine systems? Also the term "Concentration" would indicate to me that if it is DEF fluid, that it might be watered down and not have enough urea per volume of fluid injected into the exhaust stream. Maybe someone is dumping water into the tank?
     
  9. Coaldust

    Coaldust Senior Member

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    Good point, John C. Easy enough to grab the NAPA 3R201 Urea Refractometer and find out. I don't mind spending money on tools, except this one. That tool makes me depressed every time I use it.

    My best contaminated DEF tank story is from 2012. It was a new University of Alaska Seawolf Shuttle cutaway van conversion. Ford chassis with a 6.7. The def tank was filled to the top with orange soda. The empty two-liter bottles were still onboard. ?? Nobody in the motor pool fessed up to it.
     
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  10. Diego I.

    Diego I. New Member

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    Tengo exactamente el mismo problema que reporta BLANDO

    Escribo desde Bolivia, agradeceré enormemente los aportes y comentarios que me ayuden a dar solucion al problema.
     
  11. Squishy

    Squishy New Member

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    Sorry I never replied with the solution. The DEF tank sending unit was determined to be bad and was replaced under warranty. I'm actually not sure of the part name, but essentially The whole heat transfer, intake, filter, level sensor unit that fits into the tank from the top of the tank. Took nearly 3 weeks to get it backordered.
     
  12. 92U 3406

    92U 3406 Senior Member

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    I believe they call it the PETU (Pump Electronic Tank Unit).
     
  13. Paul Council

    Paul Council Senior Member

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    Just to clarify,
    Def is referred to as a catalyst reagent. During regeneration and passive regeneration def is injected in and the heat of the exhaust plus the scr causes a catalytic reaction and removes most of what noxious gas left in the process. The way it was explained to me in class one would think that egr isn't necessary anymore I raised that question and couldn't get a answer as to why egr is still being used. I did learn however that the teir5 engine doesn't use egr. I guess the smart people figured out what a dumb mechanic figured. :)
     
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  14. John C.

    John C. Senior Member

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    I was under the impression that DEF is injected into the exhaust stream constantly. The EGR was supposed to burn off the crankcase vapors instead of allowing them to go into the atmosphere. It was also part of the cooling of the firing temperature to reduce NOX. The DEF chemically combines with NOX to make some other chemical.
     
  15. Paul Council

    Paul Council Senior Member

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    Not quite constantly. exhaust temps have to be high enough for the reaction and for the nox sensors to come online. When everything is working correctly it's damn near emissions free. Teir4 is good for the ozone, but the irony is that we are burning more fuel and filling landfills with 2 gallon plastic jugs. I would like to see a carbon footprint analysis done with a teir4 final machine compared to a non teir4 machine.
     
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  16. 92U 3406

    92U 3406 Senior Member

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    Once the system is up to temperature and the DEF is thawed out, its injected more or less constantly while the engine is running. It uses the NOx sensors to determine how much needs to be injected.

    Cat is already starting to remove EGR from their engines. Check out the C9.3B. All done in the aftertreatment system.
     
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  17. LEGO

    LEGO Active Member

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    CAT calls it a DEF manifold. And yes they are prone to fail, but it is covered under the emissions warranty, but they are cat backorderd.
     
  18. LEGO

    LEGO Active Member

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    Que problema tiene la maquina? o que codigos aparecen en la pantalla?
     
  19. LEGO

    LEGO Active Member

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    This is what CAT is claiming to be the problem, in case y'all are interested to know.
     

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  20. LEGO

    LEGO Active Member

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    Wow, orange soda? cant believe the guys would do that to the def system. Sometimes I cant tell if the operators are not wanting to work, or if they are clueless or perhaps it was a hate crime, but we got a machine that the def tank was completely full of hydraulic oil. looked liked the Chinese egg drop soup :eek:
     

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