I am running a 1986 with a 351W nd the C6,I bought the top-of-the-line start from autozone whenever it started messing up last year. I have since replaced it 8 times, finally swapped them out for oreillys top-of-the-line. We finally gave in and pulled the flexplate. It had 3 or 4 dead spots in her. So we got a new flywheel from oreillys. Put it all back together (to include new battery and cables) all TODAY. Fixed the timing according to the Emission Control LAbel (8*BTDC in neutral). It fired right up and was being sexy. pulled her out of the shop and ran her down the road for a mile. Had had troubles timing it(backfiring/dying), and with the vacuum advance from the dizzy (dont know where to route to properly, think we figured it out). Turned into a drive to turn around and take her home, and she bogged and died. Tried to start and the start just whirred. Pulled the starter off, and looked at the flywheel and it was dead all around. What might cause this? MYself, my brother, my brothers father in law, my father and 2 ase certified mechanic friends looked at it and we cant figure out how it could do that after starting once.

TL;DR
Flexplate ruined after one start and a mile run, tips gone all around. What caused this? Am using auto trans starter. Any Suggestions/Comments?
I am working on it to get working. I am in the military and this is my primary (read: only) vehicle. Please Advise.

 

Is this truck all original or has the engine be swapped or been out/rebuilt? Or you are not sure? Does it have the sheetmetal spacer between the engine and the tranny?

 

Sounds like you have the wrong starter and/or the wrong flex plate for the application. Or, as Dave is suggesting, don't have the spacer. Something is wrong in the spacing, and there are different starters for different applications that have different spacing. They'll bolt up but will tear themselves or the flex plate up when run.

 

Did you compare the height of the new flexplate with the old one? There is a couple different heights that are available. You can't trust half of the people that work in the parts stores to give you the parts you actually need. Granted, there are some that know what they're doing, but the majority isn't so good. It sounds like it's definitely a problem with mis-matched parts.

 

Ok thanks guys, and yes it has that damnable sheetmetal. the engine has never been swapped by the records i have. flexplates were the same size, both teeth and diameter. starter is the same size as the stock. any other suggestions?

*Went to a junkyard for f150s here in the MO and hit up a few old fields.

 

There's more to it than just the diameter and tooth count. You also have to make sure that the depth is the same too. There are several different depths that were made. Lay the new and old ones on a flat bench or table and measure to the top and bottom of the ring gear teeth. If they are not the same (even if they are close), you will have problems.

I'm still betting you got the wrong flexplate, no matter what the parts store is saying.

 

Man I hope all of my stuff is right. I didnt compare flex plates from new to old. My new one is a scat for the c6. They looked similiar though. The previous owner said he was having trouble with the starter not hooking up right when it would throw the bendix gear out. He thought it was b/c the sheetmetal in between the motor and tranny was bent. I thought it was b/c the bell housing of the tranny was shattered. He put an Autozone starter on it 6-7 yrs ago when the Bronco was running. I hope this was before they went to crap with their starters.

 

Did you ever fix the issue? I'm having the same issue with my 1985. Got the original flexplate from 1985 bronco at a junkyard, and got a starter from everywhere including the mini high torque starters. Everything I replace the flexplate and put a new starter she starts up 5-10 times then eventually the same thing happens where it starts to bund up then just whizzzzzzz, because the gear/bendix doesn't contact the flexplate anymore. I've also replaced the guide plate for the starter (goes between engine and trans. Everything is bolted up right, done the job 4 times myself and had a shop do it 2 times under warranty and every time it's the same thing. One NEW thing I'm noticing is that when I crank it eventually the flexplate "kicks back" and that's when it usually grinds teeth on starter or flexplate. I'm thinking a possible timing issue now, I know there was a thread about the "red blue or yellow" TFI modules and how they retard the timing for easier startup, thinking this might be my issue maybe it's off?

 

There are no "red blue or yellow" TFI modules. Only black and grey TFI modules. There are blue, red, yellow and brown Duraspark II modules. But they only retard the timing for altitude while running.

But timing would be something to check. See if it's around 10 degrees BTDC. with a timing light, if you can get it running again.

 

No problems ever with Starter to Starter Ring Gear. Then all went to crap. After 6 flexplates, 6 starters. Only lasting a a week or less. Good to have warranty's. Starter checked by Repair Shop. Now on number " 7 ". Gear ridge worn off bendix Gear and same on Flexplate Starter Ring. Wear showing Starter Bendix Drive Gear not fully messed with Starter Ring.as the Top of both are stripped off. Starter flushed in mounting hole to prevent movement, unless Starter nose ( MADE IN CHINA) is off or Starter Body (Made in China) is off as well. No shims where ever on this truck that I recall, before I rebuilt the engine. That was fun by my self. Thought I RETIRED AS A MECHANIC, THATS A JOKE. Lo ! Working on Auto Electrical is easy than scratching my head on a simple Starter problem that doesn't addup.

 

From what your post has it sounds like both the starter & flex plate need to be replaced.
As one of the other older post said you have the metal plate between motor & transmission? This plate is what locates the starter and if not in place the starter is not set right and can move.
I did not read each post but on the small block motors they use a different starter for auto's and manuals. Thing is they both look the same and will bolt up but have problems like this after a while.
I cant think of anything else.
Dave ----