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Detroit 671 TI rebuild

Discussion in 'Ocean Yacht' started by Boomer, Jun 26, 2018.

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  1. Capt Ralph

    Capt Ralph Senior Member

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    Dead 8V71? thought they were running?
  2. MBevins

    MBevins Senior Member

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    Death is such a questionable thing.
  3. Pascal

    Pascal Senior Member

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    No it s why I repowered. Didn’t want to rebuild them
  4. Capt Ralph

    Capt Ralph Senior Member

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    I like the terms running take out's or re-buildable cores. Or even parting out.
    Dead is dead, nothing of use with a hole in it and full of salt water. That's pretty dead.
    That's why I asked, I would not think you would let anything blow up.
    You just didn't want to rebuild the old mules.

    The sad part, They really did not give you much cash for what they got.
  5. Pascal

    Pascal Senior Member

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    They were cores. Nothing more. I see your point between core and dead but are many of these laying around and they’re not worth much.

    Bottom line a good 8V71 rebuild is 20/24k plus 5 for the Allison. The factory reman Cummins weren’t that much more
  6. Capt Ralph

    Capt Ralph Senior Member

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    Not worth much until some one needs a used part.
    I have been a great fan of your re-power project.
  7. Capt J

    Capt J Senior Member

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    I’ve seen that with D.D. Liners when they put too small a liner in. D.D. Has 4 liner sizes depending on what the bore in the block actually measures. They used a liner 1 size too small and they did that.
  8. Capt Ralph

    Capt Ralph Senior Member

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    Yes, My stb engine 14 years ago had a sloppy fit. Had to hone the block out a bit for the next class liner size.
    Last edited: Jul 28, 2018
  9. Capt Ralph

    Capt Ralph Senior Member

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    Update;
    Seems it was a cluck fired from a good shop that did the work. Owner was not aware he was not representing the shop he usually did business with.
    Thought he was getting a good customer discount job.
    So far, a lot of reused parts and and used parts.
    Ran for a few hours well,, Then..
    The cluck also seems to have diapered,,, with the money..

    A reminder to all, do business directly with a known and reliable shop. This urine contest has near all dribbled out. Sadly, the owner has the puddle to clean up.
  10. Boomer

    Boomer Senior Member

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    Well this is weird...drained most of the oil out of the bad motor and it was very diluted with diesel..I changed fuel pump and injectors this spring...what else could cause the oil dilution issue? This is what probably caused the issue..lack of lubrication...only 50 or 60 hrs on the oil change also
  11. Capt Ralph

    Capt Ralph Senior Member

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    Where do you think the bad lungs fuel went to?
  12. Boomer

    Boomer Senior Member

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    Figured out the tail pipe with the oil?
  13. MBevins

    MBevins Senior Member

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    You kep't sending fuel into the cylinder with a hole in the Piston, it can't reach compression so the fuel doesn't burn but passes through the hole as the Piston goes up. Hence fuel in your oil.
  14. Boomer

    Boomer Senior Member

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    Wow...several gallons in a few minutes...impressive
  15. Capt Ralph

    Capt Ralph Senior Member

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    How you figure several gallons? I thought you commented the oil was low.
    It takes just a bit of fuel to taint block oil.
    The fuel pump has a weep hole to leak out of before the engine. No fuel from the pump.
    Damaged injector tip will pour in fuel.
    I assume you used new fuel tubes when the injectors were serviced.
    Futher assume the valves were ajusted and injector heights adjusted, all cold.

    Never noticed a dropped valve caused by thin oil.

    Poor bridge adjustment. Poor valve adjustment. Hot seats, bad previous seat replacment, damaged keepers and just plain luck causes dropped valves.
  16. Boomer

    Boomer Senior Member

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    When motor broke, I checked oil and it was at the bottom of dipstick. When I went to pull the rest of the oil out, it had gone over half full. I could definitely tell the difference in the oil to diluted oil as it turned almost to a water like flow
  17. MBevins

    MBevins Senior Member

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    I simply gave you the reason why a Piston with a hole in it allows fuel into the oil. I'm not on your boat nor seen your mess in person so as to why you say that you have gallons of fuel in your oil is a mystery.
  18. Capt Ralph

    Capt Ralph Senior Member

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    Running or just sitting since it happened?
    And this is after the head wad pulled off?
  19. Boomer

    Boomer Senior Member

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    It's all good...still learning...she sat for 3 or 4 weeks before head and turbo was pulled...new injectors and fuel pump installed in march...apparently oil level went up while she sat...I get the injector tip was broken and fuel poured in....a couple gallons seems like a lot...she did have a oil dilution problem when I bought her..thought the fuel pump and injectors would fix the problem...oil was also changed...50 to 60 hours on the oil
  20. Capt Ralph

    Capt Ralph Senior Member

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    Been thinking about this.
    1) The block holds a lot of oil after it was run. I tell everybody to check oil level the next morning when cold. It's amazing how far that dip stick will come up overnight.
    2) When the injectors are pulled (head removal), a lot of fuel drains into the engine (sump). Not gallons but enough to thin the oil.
    3) she did have a oil dilution problem when I bought her You did not comment if the fuel tubes (that lil pipe from the head to the injector) were replaced.
    New tubes always in my shop when one is removed. That is a fine double flare in there and can not be re-compressed reliably again. Leading issue for fuel in the sump..