Crankshaft pulley has band of rubber between the hub and the grooves to reduce
harmonic vibration. In this case, the grooves separated from the hub. His only
course of action is to replace the whole pulley. This rarely happens. That's why
we don't hear much of it.

btw, lighten pulley usually has no band of rubber to isolate the grooves from the
hub. Vibration from the pulley would destroy the crankshaft bearings fast. That's
why we don't advocate using cheap lightened pulley.

"'Curly Q. Links'" wrote:

> You didn't mention how long ago it was done, but the person who did your
> timing belt didn't tighten the bolt nearly tight enough. At least they
> didn't use LockTiTe (which is a no-no).
>
> Good thing you shut it down quickly. The key is probably lost, and
> timing belt may be damaged. You need a good mechanic to look it over and
> put it back together correctly.
>
> 'Curly'
>
> ===================