Can a stuck motor be turn from the prop?

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by Blacksslumina, Feb 26, 2018.

  1. Blacksslumina

    Blacksslumina New Member

    29
    Jan 5, 2018
    1980 Sea Ray 245
    305 Mercruiser 5.0L
    trying to turn a 305 motor that hasn't ran in years, the crank bolt was stripped by PO, and the starter just clicks when I turn the key, I jumped the starter solenoid and it sounded like it tried to move once but its not budging since then. If i put it in gear and try to turn the prop nut (power disconnected and all plugs out) is it worth trying or is there something more likely to break in the outdrive before i'd get any movement from the crank?
     
  2. NorCal Boater

    NorCal Boater Well-Known Member SILVER Sponsor

    Jan 24, 2008
    Covington, LA
    Cobalt CM23
    GM SB 383" Stroker" Alpha Gen I
    I don't think I would try that. I will admit I've never heard it done but if you break something in the drive then you have a frozen motor AND a broken drive.

    I think your best bet would be to try and get the stripped crankshaft bolt out. Can you get a large Vise Grips on it or is the bolt too recessed in the balancer? What about a pipe wrench? If the motor is frozen it may look as if you are going to have to pull the motor anyway.

    Sorry this is turning out to be so frustrating.
    Shawn
     
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  3. Blacksslumina

    Blacksslumina New Member

    29
    Jan 5, 2018
    1980 Sea Ray 245
    305 Mercruiser 5.0L
    Thanks, well then before I pull it I'll remove the logs and try to tap each cylinder in firing order through the spark plug holes. The bolt for the crank was missing when I got the boat. I ordered the correct bolt for the motor but it won't thread into the threads inside the crank, they are stripped or either they broke the bolt off in the crank.
     

    Attached Files:

    Last edited: Feb 26, 2018
  4. BillK2632

    BillK2632 Well-Known Member SILVER Sponsor

    Jun 25, 2009
    Lake Norman, NC
    1999 185 Bowrider,
    Mercruiser 4.3, Alpha I
    1. Trying to turn it from the prop will either damage the drive or coupler - so don't try that.
    2. Tapping the the piston tops through spark plug hole is also not a good idea, unless you pull the heads and work them with something close to the size of the piston - made from wood. Anything you can fit thought the spark plug hole is small and will damage the top of the piston.
    3. I think you need to keep penetrating oil in the cylinders and get the crank bolt fixed. That is really the only way to are going to be able to get it freed up, short of taking it apart.

    Maybe others with more experience will jump in - freeing up a frozen engine is an art in patience. Otherwise things get broken, often beyond repair.
     
    Blacksslumina likes this.
  5. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Sounds like you need another motor. Get a 350 this time around, 96 or later
     
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  6. atrick

    atrick Member

    142
    Mar 4, 2017
    Penna
    1995 searay 290 Sundancer
    1990 21 maxum
    Twin 4.3 mercrusers with alpha one drives
    305 chevy with a alpha one drive
    I had my 305 stuck when I didn't use it 8 years and I shot WD40 in all the cylinders and let it set overnight then next day shot some more in cylinders. There was just enough room to get a pipe wrench on the output shaft in front on the transom behind motor. Put a short pipe on the pipe wrench handle for extra leaverage and when you get it loose work the motor back and forth a little before turning it too far so it loosens up the rust. I then put fresh gas in tank and fired it up and its been running fine for years and doesn't use any oil. You don't want to try turning it with the crank bolt, you'll just break it off, it wasn't meant to be used for that, and if there isn't room for wrench behind motor pull outdrive off and turn with output shaft.
     
    Blacksslumina likes this.
  7. KevinC

    KevinC Well-Known Member

    Feb 25, 2011
    Long Island, NY
    2004 340 Sundancer
    1988 Proline Center Console - 90hp Mariner/Mercury
    1969 Boston Whaler
    Twin 8.1 V-drives
    Did you ever see the engine run before the layup? If not I would think there is a good chance that the crank bolt was stripped by the previous owner because the engine was already locked up. Perhaps more info might help but this engine could have been hydro locked years ago - I would just look into getting a new block. Perhaps pulling the heads might give you a better view of whats going on before pulling the engine.

    -Kevin
     
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  8. Blacksslumina

    Blacksslumina New Member

    29
    Jan 5, 2018
    1980 Sea Ray 245
    305 Mercruiser 5.0L
    Thanks for the advice, I get the feeling that's it almost free but I'm definitely going to have to play with it more
     
  9. Blacksslumina

    Blacksslumina New Member

    29
    Jan 5, 2018
    1980 Sea Ray 245
    305 Mercruiser 5.0L
    Well I will definitely look into that, that might just be the trick thanks
     
  10. Blacksslumina

    Blacksslumina New Member

    29
    Jan 5, 2018
    1980 Sea Ray 245
    305 Mercruiser 5.0L
    I didn't see it running and previous owner "said" he never got the chance to crank it cause he fell off the boat one day and broke his leg he had it sitting for a year. But says it was sitting for years before that. someone was def. fooling with it because the crank bolt was gone and there is a small hole looking at the teeth on the flywheel. I think someone tried but didn't put a lot of effort into it. Oil is fresh and seems like it was winterized but who knows I'm just going through the motions now. I'll pull the heads this weekend if nothing else works
     
    Last edited: Feb 26, 2018
  11. Ididntdoit

    Ididntdoit Well-Known Member

    Dec 5, 2007
    Newport, RI
    300 Sundancer
    5.0MPI Bravo III
    unbolt the crank pulley (3 bolts) take the pulley off and thread the bolts back in.....lock a pry bar (or similar tool) between two of the bolts and turn it over......the best solution to free a stuck motor is a 50/50 mix of ATF and Acetone.....good luck
     
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  12. northern

    northern Well-Known Member

    Jan 17, 2007
    West coast Vancouver to Alaska
    380 Aft Cabin 1989 GPS and Charts by Nobeltec
    Twin 454 strait shaft
    ATF is great stuff it will clean the engine inside if you put 1 QT in the engine oil in a car it will free valve lifters in a car.
     
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  13. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    How is the OP suppose to fix his thread stripped crank and a hole in his ring gear without pulling it, and seized as well?

    ATF right ?
     
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  14. Ididntdoit

    Ididntdoit Well-Known Member

    Dec 5, 2007
    Newport, RI
    300 Sundancer
    5.0MPI Bravo III
    why dont you read his question again......he did not ask for advice about replacing his motor (or even getting it to run)......he simply asked how to turn it over given his situation.......you seem to be looking for a fight......
     
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  15. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Dude not looking to fight.... The man has to look at the BIG picture
     
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  16. Boater420

    Boater420 Well-Known Member

    Mar 11, 2015
    Clearwater, FL
    '97 330 Sundancer
    V-Drives
    Westerbeke 4.5BCG
    Twin Merc 454's
    If it was me and I had an engine that was seized, had stripped crank bolts, and had been sitting for years before that I'd be looking at other options (new engine).

    Post #10 clearly spells out that the OP really has no idea what shape that engine is in because the previous owner "said" he had it sitting for a year, and before that it sat for years. It has missing bolts from where someone else was trying to free up this motor.

    He's looking for a fight because he tried to steer the OP towards a different (probably better) option? Seems kinda over the top to me. Are you gonna ask him to meet you at recess or after school?
     
    Blacksslumina likes this.
  17. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    Good advice if the OP wants to try to spin the motor.
     
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  18. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    "Small hole looking at the teeth on the flywheel"

    I would bet that would spin just fine. Yup good advice
     
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  19. atrick

    atrick Member

    142
    Mar 4, 2017
    Penna
    1995 searay 290 Sundancer
    1990 21 maxum
    Twin 4.3 mercrusers with alpha one drives
    305 chevy with a alpha one drive
    The crank pulley is the one where the bolt is broke off and he can't get the new bolt in, the pulley with the 3 bolts is the water pump pulley.
     
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  20. MickT

    MickT Member

    76
    Aug 5, 2016
    australia - newcastle
    2006 sundancer 300
    twin mercruiser 5.0 mpi w/bravo III
    It’s also possible that the engine won’t turn because the drive is seized....

    Step 1, remove the drive (gonna need to do this anyway to service the drive, and most likely replace bellows, also needs to be removed to swap out the engine...)

    With the drive removed, try and rotate the drive input shaft - nice and free, graunchy, or stuck?

    Now look for ways to fix the engine....
     
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