Alignment Pins . . . what are they and why should I care? 

Why Are Mine Missing?, Should I Care?, What Do I Do Now?


Topic:                           Alignment pins - why are they important?


What are they?:      They are small pins made of hardened steel. Their purpose is to keep the crankshaft bearings from rotating in their saddles. 


Are they important?:            Not necessarily.


Why are mine missing?:               On 60hp motors this usually indicates that it's time to rebuild the crank and here's why:

    • It's starting to get a little twist - which causes the bearing to vibrate - shaking the pins out. If you see signs of brinelling in the bearing saddles it's time for a rebuild
    • Usually the lower bearing loses it's pin first.
    • Most of the time the pin just blows through the crankcase, up the ports, through the combustion chamber and out the exhaust.
    • Sometimes it'll get wedged in the slot on the lower end of the connecting rod
    • Sometimes it gets caught in the port window when the piston goes up - causing damage to the edge of the piston
    • Most of the time you can see pieces embedded in the surface of the combustion chamber and/or the top of the piston


Should I care?:               Only if your motor was damaged (piston or bore dmage) or you plan to rebuild your crankshaft. If you have a 1990 or newer motor, it's been my experience that these motors are the worst for throwing the pins out. How bad can it get? Have a look:


What do I do now?:               Chive on 


 

 

 09/12/2017

Copyright 2012 Capt'n Obveeus

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