Oily residue in mixing elbow

Discussion in 'Diesel Engines' started by Schwingdings, Dec 7, 2023.

  1. Schwingdings
    Joined: Dec 2023
    Posts: 4
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    Location: Indonesia

    Schwingdings New Member

    Hallo friends! I have a quick question. I have a Yanmar 4jh3-TE. The mechanic who last serviced it found a little bit of oily residue in the mixing elbow and he's one hundred percent sure that this is indicative for the turbocharger's nearing the end of its lifespan. He's a very good mechanic with an impeccable reputation, but before buying a new turbo I still figured whether that's a sound deduction to make or whether there could be other reasons for the residue in the elbow. Thanks a lot!
     
  2. BlueBell
    Joined: May 2017
    Posts: 2,962
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    Location: Victoria BC Canada

    BlueBell . . . _ _ _ . . . _ _ _

    Take the turbo out and have it spec'ed.
    You have to take it out anyway to replace it.
    If it's fine, fire your mechanic and put it back in.

    How many hours on the engine?
    Is this a new-to-you mechanic?
     
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  3. Schwingdings
    Joined: Dec 2023
    Posts: 4
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    Location: Indonesia

    Schwingdings New Member

    Thanks, that sounds like a good idea. The engine's got 6,700 hours on it, but I don't know if it's still the original turbo. I only bought the boat a couple years ago.
     
  4. Schwingdings
    Joined: Dec 2023
    Posts: 4
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    Location: Indonesia

    Schwingdings New Member

    Since I'm cruising, every mechanic is always new to me. But this one has a fantastic reputation. Even the competition told me he was the best in all of Fiji.
     
  5. baeckmo
    Joined: Jun 2009
    Posts: 1,743
    Likes: 755, Points: 113, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    Not as shure... it may well be an injector that is worn or leaking. Cheaper and simpler to check first. And you don't buy a new turbo, you have the old one renovated for far less money and often a better result.
     
  6. Schwingdings
    Joined: Dec 2023
    Posts: 4
    Likes: 0, Points: 1
    Location: Indonesia

    Schwingdings New Member

    Thanks a lot! The problem is that I'm in Indonesia, and in Sorong at that. I don't think anyone here can refurbish a turbo. But I'll definitely have it taken out and inspected before buying a new one for sure.
     
  7. kapnD
    Joined: Jan 2003
    Posts: 1,395
    Likes: 472, Points: 83, Legacy Rep: 40
    Location: hawaii, usa

    kapnD Senior Member

    Turbochargers are very simple, they have only one moving part, a couple of bearings and seals. Shake the shaft, and pull it back and forth to determine wear. Beyond that, turbo boost measurements should be monitored for changes over time.
    No reason you couldn’t rebuild it yourself.
    Oily residue most commonly comes from crankcase blowby, which is another matter entirely, and not uncommon on motors metering several thousand hours.
    Look up Seaboard Marines “Envirovent” , it works great, and you can easily build something similar yourself.
    Edit:
    Oops, just noticed it’s oil on the hot side.
    Is the motor consuming oil?
    You need to figure out where it’s coming from, worn rings, valve guides, head gasket?
    An oily vapor catch can is still a good idea, can make your engine room cleaner, and less smelly.
     
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  8. BlueBell
    Joined: May 2017
    Posts: 2,962
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    Location: Victoria BC Canada

    BlueBell . . . _ _ _ . . . _ _ _

    No history paperwork on the engine?
    Too bad, you're in the dark.

    Perhaps you and the mechanic need to go for a beer.
    What makes him so sure the turbo is on it's way out?

    kapnD makes a good point, get to the shaft and give it a wiggle and a spin.

    Are you having any other service done to the engine?
    If so, this story could develop.
     

  9. kapnD
    Joined: Jan 2003
    Posts: 1,395
    Likes: 472, Points: 83, Legacy Rep: 40
    Location: hawaii, usa

    kapnD Senior Member

    Another cause of oily residue is overfilling of the sump.
    Try running at the low mark, instead of keeping it topped off to the high mark.
    The marks only indicate a safe running range, with a generous safety margin, so the low mark is not a death sentence!
     
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