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  1. #1
    Chrisrokc's Avatar
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    Let play, what made my motor let go!

    Ok this is exactly what happened.

    Ski was running GOOD. Fastest it has ever ran in fact. 73 mph full tank of gas at 500ft above sea level. I had my EFI in at 6-6-1-7. All I have motor mod wise is D-plate, VF3s, and no filter box. I was also running side gapped plugs.

    It started making noise but it ran ok still, tried to put it in, no go. Motor locked up. I took everything apart and this is what I see.

    - Middle Cylinder Rod is Broken at the top
    - Middle Cylinder is Cracked at the bottom where rod hit it
    - Middle Cylinder head is smashed up
    - Crank Casing is smashed at the bottom
    - Piston is locked in Cylinder
    - Rod bearings at the piston in Middle Cylinder are all over the place, top of piston, in crank casing... ect.
    - Crank is OK
    - Front and rear cylinders, piston, and bearings are OK
    - VF3 Reeds are OK
    - No water in hull or motor


    So in my mind I see this going down. Bearings go out. Bearings lock the piston in the cylinder and then the rod breaks off. Rod then goes down cracks cylinder and casing. Motor is locked won't start because the broken rod is jammed.


    This is what I want to know

    What could have caused this? I don't want it to happen again since it is such a pain in the ass.... even though it gives me the need to build the motor LOL.


  2. #2
    WATER WOODY's Avatar
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    Maybe the wrist pin bearing let go,causing the piston the shift all over the place.Without the bearing being 100% on the wrist pin,the slack between the wrist pin and rod journal caused the rod end to crack.The only way to confirm is to take a close look at the wrist pin.


    THIS IS 1 OF SEVERAL CAUSES FOR YOUR PROBLEM.Just something to look into.

  3. #3
    Chrisrokc's Avatar
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    Going to go take a hammer to the piston... Be back with info in a sec

  4. #4
    Altezza01's Avatar
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    could it be lack of oil? engine heating the bearing up causing it to break? just a wild guess

  5. #5
    Chrisrokc's Avatar
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    The wrist pin looks ok. Hole in the side of the piston though. Bearing is no where to be seen.... except in the bottom of the casing lol. The rod broke at the wrist pin though.

  6. #6
    Chrisrokc's Avatar
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    Quote Originally Posted by Altezza01 View Post
    could it be lack of oil? engine heating the bearing up causing it to break? just a wild guess
    I thought of that but the oil line looked good. Maybe it is gummed up? This happen to anyone before?

    There was oil in the bottom of the crank casing.

  7. #7
    WATER WOODY's Avatar
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    Actually the wrist pin COULD be ok.They are really strong.I have a feeling that the knocking sound you heard,could have been the play in the wrist pin,due to a bearing failure.Like i said,its 1 thing that could have caused this.You have pics?

  8. #8
    All hail the Chief! fullboogie's Avatar
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    One word for you - DETONATION. Really, I don't know - just guessing.

  9. #9
    Flying Scotsman's Avatar
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    Sounds like water
    Hydrolok
    Are you sure theres no water residue

  10. #10
    WATER WOODY's Avatar
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    Quote Originally Posted by Flying Scotsman View Post
    Sounds like water
    Hydrolok
    Are you sure theres no water residue
    Possible but Chris said there was no water at all.

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