"Corky Scott" wrote in message ...

Pete, I'm assuming it's hydraulic lock because the starter cranked the
prop around half a turn and then jerked abruptly to a stop.

When you get hydraulic lock in a radial, it's not that the prop starts turning,
it's that the incompressable fluid tries (and succeeds) to expand the cylinder.
You can break a cylinder even pushing the prop through bu hand when oil is present.