every time i try and start my car (91 Bird, v-6) the starter turns but wont catch every time, after 4-5 trys, usually (sometimes more), it catches and turns over, the starter is less then 5 months old and i have tried 2 selenoids, when i first put new selenoid in it worked pretty good for about a week, then went back to the way it was acting b4 i got it, have also tryed with and without shims, not much of a difference, any suggestions????

 

sounds like the bendix is stuck. try spraying it with silicone spray and moving it by hand. (bandix is the gear in the starter that engages with the fly wheel.) happens all the time on cessna's.

 

check the teeth on the starter and flywheel