Which action is advisable for maintaining proper torque on fasteners?

Maintaining proper torque on fasteners is crucial for ensuring the integrity and safety of an engine assembly. Cleaning threads and hex heads helps achieve the correct clamping force by removing any dirt, debris, or corrosion that might affect the torque reading. Clean threads allow for more accurate engagement between the threads of the fastener and the component, thus ensuring that the fastener can be tightened to the proper specification without resistance or misalignment.

When fasteners are clean, the friction is minimized, allowing the torque wrench to provide an accurate measurement that corresponds to the intended clamping force. This practice not only enhances the reliability of the joint but also helps prevent issues like bolt stretch or failure that can occur when incorrect torque is applied due to interference from contaminants.

In contrast, using a higher torque specification could lead to over-tightening and potential component damage, while avoiding lubrication could increase friction and cause inaccuracies in the torque applied. Increasing bolt size doesn't address the specific issue of maintaining proper torque on existing fasteners and can result in unnecessary modifications to the design or assembly.