What does a "wrist pin" connect in an engine?

A wrist pin connects the connecting rod to the piston in an engine, allowing for the transmission of motion between these components. It serves as a pivot point that enables the connecting rod to swing as the engine operates. When the crankshaft rotates, it drives the connecting rod, which in turn pushes the piston up and down within the cylinder. This movement is crucial to the engine's function, as it facilitates the combustion process and converts the energy produced into mechanical work.

The other options do not accurately describe the function of the wrist pin. The crankshaft is not directly connected to the pistons; rather, it connects through the connecting rod. The wrist pin also does not connect the connecting rod to the cylinder wall, nor does it play any role in linking the cylinder head to the block. The correct understanding of these components and their relationships is essential for diagnosing and repairing engine issues effectively.