Mechanical Troubleshooting — real-world interview & field troubleshooting questions with clear, practical answers. Tap any question to open its answer. Showing the first 70 questions free. The complete question bank is available as a PDF below. Bearing Faults & Diagnostics Q1 A bearing becomes unusually hot after a few hours of operation. How would you troubleshoot it? Answer First compare the temperature with the normal operating trend and check lubricant quantity, grade, contamination, and relubrication interval. Then inspect shaft alignment, bearing preload, mounting fit, and nearby heat sources. Correct the root cause before adding more grease; over-greasing can itself increase temperature. Q2 A motor-driven shaft develops a rough rumbling sound that increases with speed. What should you check? Answer Listen for the location and compare the sound at different speeds and loads. Check bearing raceways, rolling elements, lubrication condition, shaft/runout, and housing fi...