Let me lay out the issue for you... I'm the second owner of a 1989 Ford F150 XLT with neither the original engine nor the original transmission. The engine is a 300 6-cyl and the tranny is a Ford C6. Specific years are unknown.

Recently, the "original-to-me" starter finally refused to budge. Due to time constraints, I had it towed to a local shop where they replaced the starter. Three days later, after much gnashing of teeth and loud grinding noises, this rebuilt starter spun free and refused to engage anything. Taking it back to same shop, they came to the conclusion that the "original" starter had been a 10-tooth starter while the OEM starter was a 9-tooth starter, ergo the breakdown. They again installed a higher-grade (so they say) 9-tooth starter and made me fully aware that it still wasn't the proper part for the job and would probably have a short life.

As an amateur mechanic, I've acquired my knowledge by having something break and beating my head against the issue till I can fix it. A quick Internet search led me to these forums and similar issues that have been reported.

What other questions do I need to ask? What other information should I gather? I realize I should count the teeth on the flexplate to figure out what starter I need. Is it possible to simply replace the 9-tooth gear with a 10-tooth gear?

Thanks in advance for the help, these forums have already provided me with a wealth of other knowledge...

 

As a update to my original post, I may have found the solution. Chatting with my local CarQuest guy, we've uncovered documentation on this exact issue and it's repair.

It seems a 10-tooth starter is available under part number 72-3141-10 or two choices of 10-tooth pinion gears (part number 3-353 for remanufactured or part number SDN-241 for new). I'm picking up the 10-tooth gear tomorrow and I'll report back then...

 

So how did it turn out, did you get the 10 tooth gear installed?

I am having the same problem with a 1988 F-250 5.0 C6, my starter has a 9 tooth gear and it just barley caches the flywheel (only the top ¼ of the teeth show a contact pattern), some times it slips when the engine is warm. It’s like my starter is sitting to far away from the flywheel.

I think a 10 tooth gear will engage the flywheel further down on the tooth because it is bigger in diameter (I hope)

Any help would be appreciated.


Thank you for your time.

Tom Cat

 

I've been working with this problem ever since I had my 5-speed manual transmission rebuilt (1989 F-150 Lariat, V-8 302, dual tanks, 205k miles) a year and a half ago. Until rebuilding the transmission, I had no starting problems, since rebuilding the transmission I was going through starters about every 5 months until someone told me about needing to shim the starter so that the flywheel will properly engage.

Hope this helps.

mdg_wy

 

Sorry about the delay, on the upside it wasn't starter related.

After swapping in the 10-tooth starter, my truck runs like a charm! The obnoxious, metallic grinding noises have ceased... My initial attempt at simply swapping the 9-tooth pinion gear for a 10-tooth version failed, I needed to replace the entire starter. Good luck to others with this problem, it was virtually impossible to research.

CarQuest has the parts needed under the previously mentioned part numbers.

In response to Tomcat's question, the 10-tooth gear IS 0.1 inch larger in diameter and will engage 0.05 inch deeper than the 9-tooth. It sounds like exactly the solution to your problem.