Turning:
* Definition: This refers to rotating the engine's crankshaft by hand, usually using a wrench or socket on the crankshaft bolt. This is done for various reasons, like:
* Checking for binding: This helps determine if the engine has any mechanical obstructions preventing smooth rotation.
* Setting valve timing: This is part of engine rebuild processes, where valves need to be accurately positioned.
* Lubrication: Turning the engine by hand helps distribute oil throughout the engine during assembly or after a period of inactivity.
* Method: Usually done slowly and carefully, using a tool to engage the crankshaft directly.
* Purpose: To rotate the engine manually for inspection, maintenance, or assembly.
* Speed: Very slow, often a few revolutions per minute.
Cranking:
* Definition: Cranking involves using the starter motor to rapidly rotate the crankshaft. This is what happens when you turn the ignition key to start the engine.
* Method: The starter motor is engaged by an electrical circuit, causing it to spin the flywheel connected to the crankshaft.
* Purpose: To spin the engine fast enough to draw in air and fuel, creating the conditions for combustion and ignition.
* Speed: Significantly faster than turning, typically several hundred revolutions per minute.
Key Differences:
* Speed: Cranking is much faster than turning.
* Method: Cranking uses the starter motor, while turning is done manually.
* Purpose: Cranking is for starting the engine, while turning is for inspection, maintenance, and assembly.
In Summary:
Turning is like gently "twirling" the engine's crankshaft for a specific purpose. Cranking is the "powering up" that gets the engine running.
