As soon as the first replacement starter did the same thing the most likely suspect is teeth worn off the flex plate's ring gear. Engines tend to coast to a stop in the same place so the starter drive always slides into mesh with the same teeth. When rust builds up on the shaft, the starter drive is sluggish to engage and the motor can start spinning too soon. That puts a lot of stress on the edges of the teeth so they start to wear down.
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Thursday, April 11th, 2013 AT 10:59 AM