how do you know when a crankshaft is going out?

 

extremely bad vibration. typically tho, it's the bearings. if crank itself breaks, it'll make a horrendous banging, smacking sound, motor probably won't run. bearings would cause abnormal vibration, maybe metal shavings in oil.

 

Please could you describe the reason behind the question for a better understanding of you problem??.Giving some more details will help.

 

you will know when the crank goes, it isnt subtle