In Reply to: Ford 8N tractor starter won't disengage, Positive Drive type posted by Brad Cobb on March 08, 2020 at 21:01:31:
6V or 12V starter will crank but I've worked on a few fellas who had 12V batteries and nothing else was switched over. A 12V battery will spin the starter faster and sometimes will jam up -I've had to work on a few fellas that had done this. The amp draw on cranking a 6V starter is 100-150 AMPs but 12V will draw a bit more. Not a problem if it starts fast but leaving cranked for more than 10 seconds or less will get things real HOT in a hurry. I see this often with guys trying to jump start their tractor with their 12V truck or car battery. Also, a weak or near dead battery will not engage the starter and jam and hang up. Often the solenoid just click click clicks if so and is a good indicator. Both the OEM and the newer Bendix drives have all worked well for me, but I only buy from 2 or 3 suppliers but I suppose some new aftermarket stuff can be poor quality. Meantime you can take your battery and starter to your trusty, local starter/alternator shop and he will bench test under load, usually for free. While he is doing that, go thru the entire wiring system and verify it is correct -SEE LINK BELOW. If you don't already have them, get the essential manuals as well -great tools. Once system is correct and running, another good tool is a float charger like the Battery Tender.
FORD 8N TRACTOR ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS: