Tons of black smoke after replacing manifold and turbo

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Felixw9, Oct 16, 2021.

  1. Felixw9

    Felixw9 Bobtail Member

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    Hello, thanks for any help in advance.

    I have a cat 3406e that was recently rebuilt about 40k miles ago. I changed the turbo and manifold out last week and it started to smoke a lot while going down the highway. It never smoked that way before. It would smoke if I laid into the pedal pretty good but never just cruising down the highway. Also I started to get really bad fuel mileage as well. I’m at about 4.4 mpg when before I’d hover around 5.3 mpg. And on top of all of that, I get a few drops of coolant from my overflow on the radiatior. Truck doesn’t run any different but it is showing all these symptoms. Any ideas what it could be? Thank you guys
     
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  3. AModelCat

    AModelCat Road Train Member

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    Just spitballing but it sounds like you went with a different size turbo.
     
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  4. skallagrime

    skallagrime Road Train Member

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    Either that or possible loose connection on air to air too
     
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  5. Felixw9

    Felixw9 Bobtail Member

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    No I forgot to mention it was all replaced stock.
     
  6. AModelCat

    AModelCat Road Train Member

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    Ok then I'd look for a loose intake pipe as suggested above. Even an exhaust leak between the head and the turbo can cause a loss of drive pressure to the turbo.
     
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  7. wore out

    wore out Numbered Classic

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    Exactly exhaust leak, or air leak on pressure side. Unless something got into the turbo some how and damaged the fins
     
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  8. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    You got a boost leak somewhere,or a bad enough exhaust leak that you can't build boost.
     
  9. BoxCarKidd

    BoxCarKidd Road Train Member

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    Take the boot off the turbo from the air filter. Check out the impeller.
    I rebuilt a tired old Cat once and it smoked like crazy. Figured under slung muffler was full of oil so I stood on it. Should mostly burn that out quickly but it got worse. Reman turbo was bad and impeller fins were going through my new engine.
    Hope that is not your problem but do not take new or reman for granted.
     
  10. Oxbow

    Oxbow Road Train Member

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    Like maybe someone left a rag in there?
     
  11. Don379

    Don379 Heavy Load Member

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    if aint smokin, something is broken.
     
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