I just bought a 72 f100. It started fine about ten times. Now I have to try 5 or so times to get it started. The battery is new. When you turn the key it turns over for about three seconds then stops turning and makes a little whining/spinning noise. What is this noise? Is the starter going bad? Sometimes if I just turn the key a few times quickly it seems to help get it started instead of turning the key and holding it. Thanks for your help!
I'm with makz06 on the bendix drive is bad. You can replace just the drve, but with the cast of the drive and a rebuilt starter being real close nad ya got to take the starter out anyway, I would put in a whole starter. IMHO
Those same symptoms can also be attributed to a bad connection or bad cable. Check and clean every connection associated with the starter circuit on the big cables. Battery,solenoid,starter,and grounds.
Seems to happen to me quite often on the old vehicles I don't drive on a regular basis. Right now both my 72 F100 and my 68 Cougar exhibit that symptom on a fairly regular basis. The F100 will always start engaging again after I keep turning the ignition key. When my Cougar does it I have to crawl under the edge and rap the starter a couple times with a hammer and "loosen it up" and then it will engage again at least for the next few turns of the key. I plan on replacing both starters but haven't gotten around to it yet.