prop hit

Discussion in 'All Things Boats & Boating' started by IMP199047, Aug 10, 2014.

  1. IMP199047
    Joined: Aug 2014
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    IMP199047 New Member

    Hello to all I own a 1990 IMP Ashanti 19' Cudy it is powered by a mercurser 4.3 Alpha 1 we struck a rock or rocks at 10 MPH tore the prop up the hub cracked as it should limped back to shore purchased a new prop and hub kit next time out boat had no speed WOT 15 MPH at best discovered shift cable bellows was torn bildge is a 1000 GPH so water weight is not the problem mechanic is at a loss motor and out drive seem to be fine could the torn bellows cause this problem it almost is acting like a spun hub but that's not the case HELP I am at a loss:?:
     
  2. AndySGray
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    AndySGray Senior Member

    Maybe a spun hub 'like' issue.

    Check the coupler plate on the back of the motor - most have a rubber vibration damper almost exactly like the one in the hub of a prop - my guess is that has sheared and while there is enough friction for low speed as soon as revs. increase it slips instead.
     
  3. gonzo
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    gonzo Senior Member

    That would be my guess too. You can test by removing the drive and torquing the coupler. I have a tool made out of a used splined input shaft.
     
  4. AndySGray
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    AndySGray Senior Member

    If access is OK you can use a handheld laser/photo tacho to prove before you dismantle the back end of the motor and sterndrive - i.e the UJ will be at less than engine RPM at higher revs
     
  5. IMP199047
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    IMP199047 New Member

    Thank you for that information will check it out ASAP would it smell like rubber melting although I did not smell anything of that nature
     
  6. AndySGray
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    AndySGray Senior Member

    BTW if you already own a photo tacho - don't look at the current prices - about 5-10% of what most of us will have paid - SOAB :mad:

    But for IMP it can payback in a single job....
     
  7. IMP199047
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    IMP199047 New Member

    Hey Andy thanks for that info they tell m they will have to to inspec when I mentioned a laser ta they did not know what I was talki I personall I think it could b the carrier bearin what are your thoughts o what are your thoughts on that IMP199047
     
  8. AndySGray
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    AndySGray Senior Member

    Photo / laser Tacho;-

    Amazon has them for under 20 bucks! :mad:

    http://www.amazon.com/CyberTech-Dig...d=1407807328&sr=1-1&keywords=photo tachometer

    you stick a piece of reflective tape on e.g. the universal joint or any visible part of the shaft (after the coupler) run the engine in gear with it well tied to the dock. point the laser dot on the item with the sticker and press the button. If the engine RPM is say 2000 the shaft must also be 2000 - the gearing change is in the outdrive.
     

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  9. AndySGray
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    AndySGray Senior Member

    The coupler is EXACTLY like the hub on the prop - and fails just the same. You say like a spinning hub - this is the only component in the drive train like that.

    I think you'd know if the carrier bearing had enough play to allow the bevel gears to disengage as it would sound like about 46 nuts and bolts in a blender
     

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