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  1. #1
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    Crankshaft snapped?!!! How?

    Today, while fishing, my 2004 F150 experienced a major malfunction. The crankshaft snapped right under the flywheel. I stated the motor, slowly approached planning speed…normal as could be. I started to let off the throttle and I heard a severe rattle/clanking. I shut off the motor and decided I needed to figure out how I was going to get back to the ramp. I started the motor right back up. I started idling towards the cove with the ramp and the noise was horrible. but….the noise vanished above idle speeds …so off I went. When I started the boat again, to trailer it up, it again sounded really bad and normal above idle. I noticed that the water pressure was above 30 psi. No oil lights…nothing abnormal other than the noises at idle.

    once on the trailer, I removed the cowling and the plastic engine trim and saw the flywheel was wobbly loose. Scary loose. But the end of the crankshaft was still very tight to the flywheel. Upon further inspection, I realized the end of the crankshaft had snapped(I’m assuming). What was holding the flywheel to the top of the motor I’m still not sure of. Even more impressive is the flywheel still has enough rotational “grip” on the rest of the crank to allow the starter to start the motor.

    is there something else that could be wrong? I looked at the exploded view on SIM and it shows that the threaded end of the crank is one piece with the rest of the crank. If the threaded end is still very firmly attached with the nut on the flywheel, and the threaded end wiggles with the flywheel, doesn’t the crank HAVE TO BE BROKEN?

    anyways. Guess I’m motor shopping. I don’t want to invest several thousand dollars to repair the motor and have a 19 year old lower unit, fuel system, etc. SAD! it still runs so smoothly. And very strong for a 150.

  2. Member cwilt's Avatar
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    #2
    Is the flywheel is bolted to the crank shaft? Did you break the bolts? Or did they just loosen up and almost fall out?
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    #3
    Quote Originally Posted by cwilt View Post
    Is the flywheel is bolted to the crank shaft? Did you break the bolts? Or did they just loosen up and almost fall out?
    The flywheel is still very tight to the tip of the crankshaft. The flywheel, retaining nut, and what appears to be the end of the crankshaft all wobble together as one part. The stator assembly under the flywheel do not move. The timing gear attached to the crankshaft is still solidly mounted. The noise I heard was the flywheel wobbling and hitting the starter. It wobbles like a plate spinning on a stick! I can grab the flywheel with my hand and turn it about 8-10 degrees forward or backward. It feels like I can almost rip the flywheel off the top of the motor if I tried real hard.

    I don’t know. Looks bad to me.

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    #4
    If I didn’t see the end of the crank wobbling with the flywheel, as one piece, I’d think the woodruff key sheared and the flywheel was loose. But…it doesn’t look that simple.

  5. Moderator 21XDC's Avatar
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    #5
    My crank broke, And it was a casting flaw from the factory. I think it was 7 years old. I ran it for 3 years that way. I had it rebuilt and so far, So good.

    Mine broke near the bearing journals across the circle and it kept spinning.

    Marks Props 317-398-9294, 1850 East 225 South, Shelbyville, Indiana 46176 propellerman59@gmail.com http://www.marksprops.com/index.html

  6. Member
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    #6
    Sorry to hear of your motor woes, however mechanical failures do happen. The F150 is probably one of the most dependable and durable 4 stroke outboards made. I ran an F150 for over 17 flawless years before selling that boat & outboard combo.
    Last edited by PSM207; 01-04-2023 at 09:22 AM.
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    #7
    I sheared the crank in my '88/'89 Johnson 150, but I had a zillion hours on that poor thing. Triage pointed to a worn upper main bearing.

  8. Member
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    #8
    Is it possible that impact damage from the day before could have damaged the crank? I hit some stumps the day before while idling. One stopped the motor from running. I think I will call the insurance company and see what they say.

  9. Member Rick H's Avatar
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    #9
    Quote Originally Posted by SteezMacQueen View Post
    Is it possible that impact damage from the day before could have damaged the crank? I hit some stumps the day before while idling. One stopped the motor from running. I think I will call the insurance company and see what they say.
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    #10
    You also need to inspect the balancer assembly for damage after an impact hard enough to damage flywheel.

  11. Member
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    #11
    Well. I have the boat at a shop. The mechanic looked it over a little yesterday. The motor is basically trashed. The power head would need a complete replacement (rebuild) and the lower unit is kinda beat up. Bent prop shaft.

    so…..I have purchased a new SHO and I am waiting for the insurance adjuster to see if insurance is gonna help me out. Hopefully so, but I already bought the new SHO, so it ain’t the end of the world if insurance tells me to pound sand. Haha.

  12. Member Rick H's Avatar
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    #12
    Thanks for the update. If you paid your premium and had the coverage they should pay something.

    Steve McQueen "Le Mans"
    Own the Champ! Life Long Petty Fan!

    2003 ChampioN 2006 250 Merc. XB, Prop By Mark C.
    2002 Ranger Okeechobee Special EvinRude Ficht 90 / 9.9 4-Stroke GLAD to have a Get me to the Dock motor maybe!

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    #13
    Yes on the impact. Impact covered under insurance. But why the power head bad?

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    #14
    Quote Originally Posted by rid 05 198 View Post
    Yes on the impact. Impact covered under insurance. But why the power head bad?
    The crankshaft broke inside the top main bearing. Crank is trashed and no way to remove the flywheel in order to replace the crank. Also, when replacing the crank, it would need new bearings and seals. That would require line honing the main journals and at that point, the labor is exceeding the costs of a remanufactured power head. Would also likely trash the flywheel as well. That’s $1200+ for the flywheel.

    sad….because the motor runs extremely well, and the flywheel is permanently welded to the top bearing haha. It still starts and runs great, but the flywheel hits the starter at idle.