Diagnosing Oil Loss in SD33T

Discussion in 'Diesel Tech' started by Jim, Apr 4, 2019.


  1. Jim

    Jim High Wheeler

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    Hi All.

    You might have seen my engine build thread below. It was a long process of overhauling the engine. Overall, the engine runs quite well, however there are some things wrong. I got so tired of working on it that I put it up for sale. Later I decided I had put too much work, time and money into this project to let it go. So now I am trying to figure out what exactly is wrong and how to proceed.

    Problems:
    1. Oil leak at rear of oil pan. I redid the oil pan gasket. Seems to slow it down, but there is still more of a leak here than desired. Im pretty sure, but not positive that it could be the rear main seal. (seal is new and crank polished at time of build).
    2. Im not sure but I think it might be losing oil somewhere else (like burning it)
    3. Has a harder time warming up then my other SD 33T. But once warm it runs fine. It will always start right up even in very cold weather with no block heater, but takes a few minutes longer than normal to warm up.

    I have some experience with #3 in my Blue Scout. I had a cold start problem and tried to solve it for years. It turned out to be a poorly done valve job that was done with a cheap valve machine. My new machinist knew exactly what to do and fixed the head by redoing the valves. Problem solved. Well this same machinist did the machine work on the engine in question. So I figured the valve work was done correctly. But maybe he missed something.

    Im not positive but it appears that this new engine build has a more smoke out the down tube then my other. ITs hard to measure the difference. This is making me question the piston-ring-cylinder set up. Does this sound right? It could explain the cold start issue. I kept the original liners, but put in new pistons and rings. The liners measured out good (checked by me and the machinist and our numbers agreed).

    Im really not sure where to start. Im tempted to pull the head and have the machinist look at it again. However, there is no oil in coolant or coolant in oil or noticeable external leaks. I am also tempted to pull the engine, replace the liners , then have the machinist reinstall the pistons with the same rings since they are essentially new and also check the head (again). Then I would finish the build. At the same time, check and rework the main seal. This would be costly (liners, gaskets, machine work). If I redid the build, it would be pretty clean work and I would not have to take the entire engine apart , just whats needed to get the liners removed and replaced. I do have a liner puller.

    Anyway, Ive got a lot of time and some energy. I just dont have a good plan yet. Looking for advice on where to start and what to check. Start with things that dont cost much time or money.

    Thanks in case you have some suggestions.
     
  2. Mustang

    Mustang Farmall Cub

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    How many miles do you have on the rebuild? It's not to uncommon for a diesel to need a few thousand miles to get broken in. Also did you hone your liners and leave a good crosshatch?
     
  3. Joe S

    Joe S Farmall Cub

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    Have you checked downstream of the T/C for oil in the exhaust pipe or in the intake indicating bad seals?
     
  4. Darrel

    Darrel Y-Block King

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    Drive it to the machine shop. Let him look at it in person.
     
  5. MyDieselScout2

    MyDieselScout2 Farmall Cub

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    I agree with joe s, check if your spitting oil out the exhaust.

    Check the rear right corner where the engine block and cylinder head meet, if your leaking oil from that corner, you probably overlooked the oil O ring.

    The other thing to look for is check the gap between the oil pan and transmission, the rear main seal may have damage cause the dowel pin was not backed out at the flywheel. Many variables.

    Also make sure your running standard 30 weight diesel oil.

    Helps to post pics.


    Sent from my iPhone using Tapatalk
     
  6. Alex

    Alex Farmall Cub

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    In addition to wrenching, I am a precision rifle shooter.
    Every barrel is a system unto itself. It shoots well with different loads than any other.
    Having rebuilt an engine or two (or two, or three) I can state that engines are like rifles. Every one is different.
    You don't state whether you are losing significant oil from the crankcase.
    Maybe your rebuild just takes a couple of minutes longer to warm up? No big.
    Drive the piss out of it and enjoy it.
     

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