Folks,

I noticed this on occasion as I was troubleshooting starting issues when I first got my 78 Bronco around a year ago. It's gotten worse over time and now happens after every start. After cranking the truck, as the starter gear is retracting, there is a good bit of grinding. The issue only happens after the key is retracted from the ignition on position. It's almost as if the teeth are trying to re-engage the starter. Is it possible that the starter gear tries to re-engage the flywheel after the crank? I've already replaced one starter due to a damaged gear. Could it be how my solenoid is wired?

I've recently replaced the battery, solenoid, starter, and within the last year, the alternator.

I've read a ton of stuff on here regarding gear mesh with flywheels, however that doesn't appear to be the issue with my truck since it never shows when cranking.

 

Yes it could be how the wiring is.

Take off the starter and test it on the bench. If the starter engaged too long then it could be the starter.

Could be the spacing too

 

Yeah, there are many possible issues, but from my experience I'll tell you most of the times the internal solenoid is the cause. Obviously, checking the wiring and cleaning connections/connectors is always a good thing (wire brush is your friend). If you do take the starter off and for a bench test and decide to crack it open, I recommend replacing the brushes.

 

So you agree that I can rule out the flywheel?

The other piece of information that I failed to mention is that I recently had my transmission rebuilt. When I got it back from the shop, the idle speed was much higher. Is it possible that this is also causing the interference?

I'll try and drop the fuel mixture today to see if that helps with the problem.

Im surprised that a brand new starter would engage for too long. How could I know if something is too long or too short?

 

Idle speed should have nothing to do with it since you are starting a stopped engine.

Also if your transmission is auto..you have a flexplate.
Manual transmissions have a flywheel.

To check it..take off starter. Look at the teeth on the flexplate/flywheel..which ever trans you have.

Have someone use a socket and socket wrench to rotate the crank shaft to rotate flexplate/flywheel.

Please undo your battery cables before this. Put trans and transfer case in neutral as well.

 

Yes, however my issues is not during startup, but actually after the flex plate is revolving and the engine is running.

Step 1. Turn key to crank
Step 2. Engine Cranks (no grinding) sometimes for a 5-10 seconds.
Step 3. Engine fires up (no grinding)
Step 4. I release ignition and key (grinding lasts a second or two)

The issue is at the instance that the engine is turned on and I release the key. It's almost as if the starter is loose or trying to re-engage the flex plate.

I'll check the teeth none the less.

 

Sounds like the wiring on the solenoid is wrong or solenoid has an issue by resending power to the starter and engaging the gear

 

I just googled 1979 Bronco starter & some of the results mention a 9 tooth starter gear, Dont know if that means there are also some 400 starters with a diffferent tooth count.Check with a Ford dealer parts dept. on this. Some guys with Rangers have mentioned problems with the wrong number of teeth on the starter gear.

 

Ok, so I wired in a kill switch and cleaned up the wiring in general. I tried to crank it to see if it would be resolved, and nothing.

What got rid of the problem was adding two 1/8" washers at the two mounting bolts. This spaced off the starter and killed the problem.

As I mentioned, the issue was during the point that the starter was disengaging from the flex plate after the truck was running. It felt like it was just barely touching the plate. The issue started after changed my first starter a year ago. Since then, I under warranty I replaced the starter that was damaged with the same make and model causing the issue again.

 

Kind of figured it could be the spacing