What tool can be used to test for play in the differential bearings?

A dial indicator is an ideal tool for testing for play in differential bearings due to its precision in measuring small distances. When checking for bearing play, the dial indicator can be set up to measure any movement or clearance in the differential assembly as it is manipulated. This precision is crucial because even minimal play can be indicative of wear and could lead to significant problems if not addressed.

The dial indicator functions by providing a clear visual readout of any movement, allowing a technician to accurately determine if the bearings are within acceptable limits or if they need to be replaced. This tool is specifically designed for measuring linear movements, making it highly suitable for this type of inspection.

Other tools listed, such as a torque wrench, odometer, or vacuum gauge, do not serve the purpose of measuring bearing play. A torque wrench is used for applying a specific torque to fasteners, an odometer measures distance traveled, and a vacuum gauge assesses the vacuum level in an engine, making them unsuitable for diagnosing bearing condition in differentials.