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  1. #1
    TX21's Avatar
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    Oil bath question 787 RFI

    I tore down my first 787 and notice some oil in the bottom end. My questions is: Is the oil in the bottom of the case for the counter shaft supposed to flow into the bottom end (crank) as well? I am doing a top end and notice some oil in the crank when I lean the ski over to the left. Seems to me it would not run right with some oil resting in the bottom end.


  2. #2
    TX21's Avatar
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    No body knows? Someone has to know.

  3. #3
    What part of DFW are you in? I am having some issues with a 787 myself. There is a cavity that the R/V shaft runs in that is susposed to stay full of oil as well. If the crank seals, r/v shaft seal, or the cases themselves leak in that area it will drain oil into the crank case itself. Causing it to blow excess smoke, foul plugs, things like that. If you are running it premix it has the potential to drain the area totally and will caouse engine failure. If you are still running the oil pump and the oil resivoir AND the seals are leaking you may have noticed it using the oil faster. Hope this helps....

  4. #4
    TX21's Avatar
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    I bought this ski not running so I don't know what the history is on it. My 787 is fuel injected so I can't go pre-mix. I am going to drain the oil and see if the fluid drains too. I am near the DFW airport.

  5. #5
    Well if it wasnt running then I am sure it had other issues, If you are getting a rebuild then you should not worry about it. I have been told that there should be no oil in the crankcase except the fuel oil mixture that is coming in. This will always leave a little oil in there but not much. If oil does collect in the bottom of the case the natural operation of the engine will suck it out and burn it up. This is my understanding from lots of reading if it is incorrect someone please chime in.

    I am South of Dallas, although I did used to live in Grapevine. Let me know what you are going to do and where you are going to take your 787 and how much you spend on a rebuild as I am looking for the same thing this winter.

  6. #6
    TX21's Avatar
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    OK, I am going to do it myself. There is too much oil in there to run IMO. I am going to yank it and drain it. The crank seem to be fine (-.058 play on big end) I am going to do a topend and lightly hone it. A place in florida sells the whole top end kit with gaskets and wrist pin bearings for about $250 so I am gonig that route.

  7. #7
    Then you probably have a bad seal or worse case scenerio the cases are leaking. The R/V shaft seal is very easy to replace and I would do that for sure. I am not sure how easy the crank seals are to replace. I think you have to tear down the whole crank to do so and that means more $$$. The case had so much oil in it probably because a seal was bad and the gravity was just letting the oil fill up the case. I would look into it before I got it back together and found the problem again. To check it do this.... there are 2 barbed fittings on wither side of the crankcase one under the carbs and the other on the exact other side. Either cap one hose off completey or fasten them together with a "T" fitting and the pressurise the system to about 6psi. (what I have been told) If you have a seal leaking it will either lose pressure or you will see oil coming out of the RV shaft hole. If it is leaking out of another seal I am not sure if you can see it or not with the jugs removed. Hope this helps, I would try it for sure.

  8. #8
    96XPSS's Avatar
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    A puddle in the bottom of each cylinder crankcase is normal. It is unburned oil. No big deal. Excessive smoke when starting or running is an indicator of problems. You should read other threads...they can help you.

  9. #9
    TX21's Avatar
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    Pulled the motor and it was really oily water!! No fluid should be in there save a little bit of oil.

  10. #10
    do you kwow of any reputable engine rebuilders here in the DFW area for these engines?

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