An engine's upper and lower center main bearings show more wear than the ones toward either end of the crankshaft. Technician A says this wear pattern could be due to a bent crankshaft. Technician B says it's due to misaligned bearing bores. Who is right?

The scenario describes an engine where both the upper and lower center main bearings exhibit more wear compared to the bearings located at either end of the crankshaft. This specific wear pattern can indeed be indicative of a bent crankshaft.

When a crankshaft is bent, it causes uneven stresses and loading on the bearings, particularly affecting those in the middle due to their positioning under greater torque forces generated during engine operation. As the crankshaft rotates, a bend can lead to inconsistent clearance between the crankshaft and the bearings, resulting in accelerated wear at those central bearings.

While misaligned bearing bores could also lead to uneven wear, this issue typically manifests as a more general wear pattern across all bearings rather than a localized increase in wear at just the center. Therefore, Technician A's assertion that a bent crankshaft could lead to the observed condition accurately reflects the nature of the problem.

In conclusion, the evidence aligns with Technician A's reasoning, confirming that the correct answer focuses on the potential impact of a bent crankshaft on the wear patterns of the bearing.