Possible reasons my flywheel teeth sheared off

[Kershaw]

I installed a jb racing flywheel (they have no warranty unlike rhd engineering) 2 years ago. Driven maybe 5000 miles.

The starter was very securely mounted, even busted my hand on the steering column when I broke the bottom bolt loose. It happened like this: I got in my car with the intent to drive to the BMW meet, turned the key, *wrr* crunch. Got a 22mm wrench assuming a broken timing belt, rotated the engine by hand a rotation while observing the camshaft also rotating, got back in the car, turned the key, *wrrrrr* crunch.

The engine always rotated easily by hand. Not hydrolocked or frozen or anything else I can determine. Maybe the starter quadrupled its power over a week of sitting and now it just decapitates flywheel teeth. I don't know.

I pulled the head off ( I was going to install a cam and do the hg anyway) but found nothing in relation to the flywheel damage. I ordered a rhd flywheel but I don't want to install it if the problem still exists.

I guess my next course of action is to reinstall the head and see if it crunches a third time? Lol. I will be installing a different starter just in case.

Any thoughts?

https://i.imgur.com/RN1NpQn.jpg

[ahlem]

Check for shiny spots on the starter gear and anywhere else that may have come in contact with your flywheel. With the suspect starter removed, can you actuate it with jumpers to see if it gets stuck in the "on" position? Is your ignition switch in proper operating condition and not such that it would activate the starter while the motor is running at say 5000 rpm?

[Das Delfin]

Could be as simple as a rock that was caught between your flywheel teeth and starter teeth at just the right time.

How many teeth on the flywheel are broken? If there's only one broken tooth for every few good teeth, as evidenced in your picture, I'd expect you'd hear a distinctive non-constant "wrr" sound. +1 check your starter gear

[Kershaw]

The starter has 1 tooth that is also now damaged. The leading edge is slightly flattened.