Which tool is used to check crankshaft endplay?

The correct choice for checking crankshaft endplay is a dial indicator. This tool is specifically designed to measure small distances with great precision, making it ideal for observing the lateral movement of the crankshaft relative to the engine block. When checking crankshaft endplay, one would typically attach the dial indicator to a fixed point and then push and pull on the crankshaft to register the amount of play on the dial, providing an accurate measurement of endplay.

In contrast, other tools such as an outside micrometer and an inside micrometer serve different purposes. An outside micrometer measures the external dimensions of an object very accurately, while an inside micrometer is used for measuring internal diameters. Neither of these tools is suited for measuring the movement or play of the crankshaft itself.

A thrust gauge, while it may seem relevant, is not commonly used for this specific measurement in the context of crankshaft endplay. Its application might be more aligned with measuring the actual thrust surfaces rather than measuring the play of the crankshaft within an engine. Therefore, the dial indicator stands out as the most appropriate and effective tool for checking crankshaft endplay due to its precision and ease of use in this application.