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Cat DGN Turbo Failure and Air pre-cleaner heat damage

Discussion in 'Dozers' started by Philip S King, Jun 27, 2020.

  1. Philip S King

    Philip S King Well-Known Member

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    My best guess is : muffler rusted and restricted. Caused Exhaust back-flow through dust ejection - caused motor to run hot - caused air cleaner to accelerate restriction through dust load and melting pre-cleaner pitons.

    Would appreciate the opinions of others.

    Also, Although I have removed the turbo. And assembly cautions and procedures would be greatly appreciated.

    Also, How can I determine if I need to replace my muffler. Should I go for a cat muffler or aftermarket.

    Thanks
     
  2. Jonas302

    Jonas302 Senior Member

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    If you melted precleaner the venturi in the muffler is bad needs replacement I would use Cat
     
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  3. Philip S King

    Philip S King Well-Known Member

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    Yea thanks, although, the ejection pipe (all or part of the venturi) appears intact. But, i also wonder if there is exsaust restriction i can't see. I guess I need to bite bullet order muffler, precleaner, elbows gaskets clamps. The spending has me spinning. Thanks
     
  4. Philip S King

    Philip S King Well-Known Member

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    I have an after market outlet pipe to mount on top of the muffler. Hope it is proper. Anyone one know it this pipe has special properties that participate in dust ejection system?
     
  5. Philip S King

    Philip S King Well-Known Member

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    Looking down into muffler
     

    Attached Files:

  6. Nige

    Nige Senior Member

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    Price of owning big Yellow Iron.

    That is not correct IMO. I think the installed muffler might be an aftermarket one and not built the same as a Cat muffler. Can you see a Part Number on it anywhere.?

    Go back to your original thread and look at the links I posted. There should be three "bulges" for want of a better word in the exhaust pipe that are just above the outlet for the dust ejector suction line. That shape accelerates the exhaust gas flow to create a good suction in the dust ejector system.
    See photo below to give you an idea what things ought to look like. Note that your machine is not exactly like this because on yours the dust ejector is built into the muffler, not part of the stack as shown in the photo. However the design will be basically the same. It is possible that your machine might have the bulges in the stack and the ejector nozzle in the muffler. Get hold of a genuine new Cat stack pipe and check would be my first thought before buying a new Cat muffler.

    upload_2020-6-27_21-10-31.png
     
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  7. DB2

    DB2 Senior Member

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    Was a discussion on here recently about the same thing on an 8T I believe.
     
  8. Philip S King

    Philip S King Well-Known Member

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    Thank you, yes I read the post. This machine just had an elbow sitting top the muffler. Figure they drug it off running through a swamp? I ordered, before I got to this diagnostic level, a after market pipe. I have not yet opened the box to have a look. Thank you for the link. It does have my curiosity. I don't believe the post was specific for my machine D6N. If the after market does not look the same not sure if the systems are a close match? Ugh. But, regardless, I am worried my muffler is obstructed . I don't want to unnecessarily purchase a new muffler. Wish I could tell if the muffler is bad.
    At the same time, I need to get this machine in the field. I also don't want to have it in the field and have to tear it apart in the baking sun. Decisions Decisions
    I really appreciate your help.
     
  9. Philip S King

    Philip S King Well-Known Member

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  10. Nige

    Nige Senior Member

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    A few quick and dirty checks, one of which you can't do until you get the replacement turbo installed: -

    1. Does the muffler have any identifying marks on it to determine if it's OEM or not.? For example a Cat Part Number, Cat logo, etc, etc. If it is genuine Cat then based on your photo it appears as though the three dimples to create the vacuum for the dust ejector should be in the stack pipe. Look in the aftermarket one you bought. Does it have them.?
    2. Is the muffler rusted externally, showing signs of splitting along the seams, etc, etc.?
    3. Run the engine with just the muffler installed, no stack pipe in other words. Is it blowing exhaust gas out of anywhere else other than the stack pipe connection.?

    If the muffler turns out to be a Cat one, it's not rusted and blowing gas anywhere it shouldn't, and the dimples for the dust ejector are in the stack pipe I'd say the likelihood is that it does not need replacement.
    One thing I will say though. If the dust ejector vacuum nozzle is in the muffler and the dimples are in the stack pipe, correct installation of the pipe is critical in order to have the two components at the correct distance from one another to create the necessary vacuum.
     
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  11. Philip S King

    Philip S King Well-Known Member

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    I noticed some heat stain streaks on the engine. I'll take a closer look at this and the new pipe.
     
  12. Philip S King

    Philip S King Well-Known Member

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    I went ahead and ordered a new muffler. Just can't tell how restricted it is. Read, source for turbo failuer can be heat caused by exhaust restricted exhaust. Also, common cause of dust ejector melting. Looked at new cat muffler
     
  13. Philip S King

    Philip S King Well-Known Member

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    Cat exhaust outlet pipe does not have the dimples. It is just a straight pipe.
     
  14. Nige

    Nige Senior Member

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    Then in that case the muffler must contain both the nozzle for the dust ejector and the dimples to create the vacuum. From the photo you posted earlier that would appear to indicate the currently-installed muffler is an aftermarket one, and maybe it caused the melting issue in the precleaner.?
     
  15. Philip S King

    Philip S King Well-Known Member

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    I don't know. I don't suspect the muffler is aftermarket . I have not found any evidence that D6N relies on demples above the piton tube for sufficient vacum. I assume, the hot pressurized exhaust gas rushing by the piton tube creates some vacum. But I don't know.
    I did read the other post .
     
  16. Nige

    Nige Senior Member

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    I can tell you without fear of contradiction that the dimples are necessary to create the necessary vacuum in order to generate sufficient suction in the precleaner. It’s basic physics, venturi effect.
     
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  17. Philip S King

    Philip S King Well-Known Member

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    Well, I got a D in Physics 101 and dropped out of Engineering school. Never made it to fluid dynamics. So I will bow out of any dissent. I have looked hard for the dimple mechanism in the D6N have not found it yet. Maybe it is in the new muffler I ordered. I ordered the Cat pipe . But, after looking at it , confirmed it is just a tube with no deformation. Other than the tube and the muffler I have seen nothing else. My existing muffler, after the up turned piton tube, is just a round hole. I will let know what the new one looks like. I have not found any D6N specific literature that depicts the dimple structure. Muffler should be tomorrow. Not sure why my pre-cleaner got hot or why the turbo seized. the chance it was restricted exhaust is my best guess. I was afraid to just try old muffler because not sure , even with machine running, how to properly check it.
    Your help is appreciated. Thank You .
     
  18. Philip S King

    Philip S King Well-Known Member

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    If I had completed the Engineering degree , I probably would not be hanging out with dead rats in the oil soaked belly of a D6N.
     
  19. kshansen

    kshansen Senior Member

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    Seems I recall someone else here some time back had a problem with the exhaust on a Cat machine and the problem turned out to be those dimples. On his system they were apparently miss-formed during manufacture and causing too much restriction. I believe he ordered a new pipe/muffler and when compared there was a very obvious difference.

    Not sure how to do a search on that one!

    Well I did find the one I was thinking about:

    https://www.heavyequipmentforums.com/threads/d8r-how-much-smoke-3406c-engine.79377/

    Not sure if it relates to this current problem in this thread.
     
    Last edited: Jul 1, 2020
  20. Philip S King

    Philip S King Well-Known Member

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    Haha, just had a thought. I believe the exhaust tube entire diameter is smaller diameter than the mufflerr pipe just after the .connection. this may be the venturi mechanism.