what would happen if this was done accidentally while the motor is off??

 

Absolutely nothing.

At the scrapyard, when checking out an engine, I typically spin the pulley more than three turns left and more than three turns right to be sure it rotates freely. If an engine is carbon locked or a broken seal or other foreign object is stuck in the engine, it will usually have much more resistance turning in one direction.

 

im changing my water pump and i accidentally turned it the wrong way. thanks, what a relief .