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komatsu pc210 VGT turbo 6.7 cummins

Discussion in 'Excavators' started by davecampbell, Dec 5, 2021.

  1. fastline

    fastline Senior Member

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    I think I would take your cold vs hot testing much further. In many cases, low boost is a product of something else going on. While cold I might throw the machine on a relief and record all the data you can. Then do the same hot.

    Stuff that I would certainly want to look at is injection event pulse width if they offer it, but "throttle %" might be all you get. Fuel rail pressure, etc. Everything to do with fuel. One hunch I have is high return rates on your injectors which would cause low rail pressure, but typically would also present with wider injection pulse width as it is trying to get more fuel.

    However, I don't recall what fault codes are being presented currently, if any? Those codes or lack thereof are an important piece.
     
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  2. LACHAU

    LACHAU Senior Member

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    Since there are many sensors used as input parameters to the ECU to process and control the VGT, we must read to keep track of all these parameters.
    In addition, we also need to pay attention to the lubrication system and cooling system for VGT.
    I think that the change in speed reduction of the VGT unit when the engine temperature increases are also partly affected by the two systems mentioned above.
    ScreenShot_20211225120623.png

    HOT ENGINE.jpg
     
    Last edited: Dec 25, 2021
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  3. davecampbell

    davecampbell Senior Member

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    thanks Ill try to get those tomorrow
     
  4. davecampbell

    davecampbell Senior Member

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    I found a missing stud on my intake heater. With the insulator missing also its almost a 3/8 inch hole. Hopefully that is my boost leak. If so, it only showing up when warm still is confusing to me. 20220105_111325.jpg
     
  5. fastline

    fastline Senior Member

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    I'm sure the expert will arrive shortly but I don't believe an air leak there will cause a spool issue with your engine, but can certainly allow unfiltered air to enter the engine which could cause engine or turbo damage. Let's hope that is a minor leak. Did you do any blowby testing on this engine? Can you visibly see the turbo compressor wheel at this point? Check turbo for axial and radial shaft play and visual inspection of fins and clearance to housing.
     
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  6. davecampbell

    davecampbell Senior Member

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    The intake heater on this motor is located after the intercooler and before the EGR. Its pressurized there so it shouldn't suck dirt in, should blow it out. It was blowing air out when I found the hole. Testing it cold I got 2 lbs more boost than prior. Im anxious to test it warm to see if this is the only issue.
     
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  7. fastline

    fastline Senior Member

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    Man, that would be a find! However, that would have to be a very serious leak to blow all your boost away there. Certainly worth the test and glad to hear your grid heater is on the pressure side. Maybe you can find some more leaks!
     
  8. davecampbell

    davecampbell Senior Member

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    I was still getting boost around 22lbs cold and 18 warm. You dont think a 3/8 hole is a serious enough leak to cause my problem?
     
    Last edited: Jan 6, 2022
  9. John C.

    John C. Senior Member

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    I would have thought those were studs going into blind holes. Cold air is more dense so I could see a change in charge air pressure with an open hole like that.
     
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  10. fastline

    fastline Senior Member

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    I was under the impression that the air leakage was occurring between the gasket surfaces due to missing one of the corner bolts. Yeah, if that bolt or stud actually enters the pressurized air passage, that would be more air. Still though, you have to remember turbos are designed to be HVLP air delivery. They move a lot of air, especially up on turbo curve.

    Give er a good test and hopefully you found it! But I was under the impression all your boost was going away? I can certainly argue from the engineering side how the air density changes from cold to hot would have more influence and pressure loss when hot. That part does make plausible sense.

    Without going way overboard explaining fluid dynamics and air springs, basically as the pressurized inlet air gets warmer, it gets harder for the turbo to achieve target boost pressure due to reduction of air density. It is moving the same "volume", but less dense air is more "springy" so it is harder to compress, especially with a leak.

    Keep us in the loop!
     
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  11. davecampbell

    davecampbell Senior Member

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    Worked it for 5 hours today with no issues so I think the missing stud was the issue. I think Id have found it sooner if I wasnt perplexed by it only doing it hot.
     
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