How in the world did my cranks shaft snap?

[JTracy]

A friend gave me old 1987 model deckboat with yamaha pro v 150 on it ('87). My family had a blast for a day and then the next morning the crankshaft broke snapped in half right below the fly wheel. BUMMMER! Anyone ever heard of that happening before and why?

 

[rodbolt]

Re: How in the world did my cranks shaft snap?

seen it a few times on many makes.
usually its caused by a sudden mechanical engine seizure or an improper replacement procedure of the flywheel.
and sometimes its simply metal fatigue.

 

[PS94]

Re: How in the world did my cranks shaft snap?

Yup, like Rod said, sudden failure. Yor bottom end siezes solid, and the inertia of the flywheel just wrings the crankshaft off...

 

[JTracy]

Re: How in the world did my cranks shaft snap?

That is what I thought which makes me think the engine is shot. I've got it at a shop now with a gentleman who said it is usually a loose nut on the fly wheel or too high rpms. He says he can replace it with a used shaft he has and can have her running good again. Does that sound realistic or would you look for another used motor?

 

[deejaycee_2000]

Re: How in the world did my cranks shaft snap?

I snap my cranks all the time, it is from over reving .... they can replace it no problem ....

 

[JTracy]

Re: How in the world did my cranks shaft snap?

thanks for your help.