A bearing should not be heated to a temperature exceeding how many degrees Fahrenheit unless specified by the bearing manufacturer?

• A. 350
• B. 250
• C. 150
• D. 200

Answer: (B)

When installing a bearing, heating is used to expand the bore so the bearing can slip onto the shaft without forcing it. But too much heat can damage what’s inside the bearing—the lubricant can break down or be expelled, seals can be damaged, and the metal races can lose temper or change tolerances. For most standard grease-filled bearings, the safe upper limit is 250°F (about 120°C). Exceeding this temperature risks degrading lubrication and component integrity, which shortens bearing life. If the manufacturer specifies a different limit for a specific bearing or lubricant, follow that instead.