Last month when I went to start my truck to go to work, I was greeted by the old "click, click, click" when I turned the key. It was still cold then, so I suspected the battery. I tested the battery and it was fine, so I checked for corrosion, loose connections and ohm'd the battery cables which checked fine. I replaced the starter with a NAPA rebuilt unit and a new solenoid.

It was working fine until yesterday when I noticed a "harsh engagement" when I started it a few times. Today, it sounded like the bendix drive was'nt kicking into the ring gear and just made a whirrring sound. I tried a few more times until finally it started. When I got the truck home I put my original starter back on (which I had rebuilt locally and put on the shelf) and it's doing the same thing, just whirring and will eventually start after a few tries. When I pulled the NAPA starter off, I noticed the gear teeth were chewed. I also noticed the ring gear teeth have a slight amount of damage as well, although I have seen much worse. The starter bolts were tight when I removed them each time. I'll hook up a remote starter switch tomorrow and watch what happens with the inspection cover removed. I guess I'll be pulling the trans and replacing the flexplate this week. Any thoughts or suggestions why this is happening? Thanks. (1979 F100 302 C4)

 

Could ya have a weak starter drive on both starters? AND it is not uncommon for NAPPA starters to fail out of the box. Maybe low voltage and it's not throwing the starter drive in all the way. If it starts quick without turning over much than it may not show up in slow cranking.

 

It's possible they could be weak I guess. The original has almost 300,000 miles on it, but it's funny it just started today along with the replacement. I have heard about some bad alternators and starters from NAPA, but I thought they had that situation resolved.
I'll check cranking voltage tomorrow. Thanks.

 

Hey just a thought but have ya check yer bell housing bolts? I have seen them back out just enough to open up a gap betwixed the trans and engine and do just what yours is doing.

 

I never thought of that, but I will be sure and check for that as well. That would be a good explanation for why it would grind one minute and whirr the next, if the gap were opening and closing. Thanks.