Crankshaft testing for wear

A crankshaft can have several issues, but this article addresses only one: wear.

One must assume that the rod bearings have some oil to lubricate the rollers.  Even with this oil, one may perform a few simple tests.

  1. Gently rotate the rod and feel for looseness or roughness.  If you feel either, then it should be considered to be bad.  Sideways play isn’t an indicator of much of anything.
  2. If it passes those simple tests, then it is time for a more accurate test procedure.  The oil must be washed out of the rod bearings.  Use a light, thin solvent liberally while working the rod to assist the solvent in doing its job.  I like to use air pressure to clean out the solvent.  Then repeat the procedure a few times.
  3. Make sure that you are in a very quiet place.  Lift the wrist pin end of the rod and gently pull on it with one hand.  Using the heel of the other hand, give the wrist pin end a gentle bump.  You have a problem if you hear any click, no matter how slight.  If this procedure is new to you, then I would suggest trying a variety of “pulls” on the rod and the amount of bump.  You should not find any play evidenced by a click.

Updated 15 July 2022