🔍 Key Concepts

• Pyrometer thermocouple operation – how temperature is sensed and converted to a reading • Effect of insulating or coating the hot junction on heat transfer • Difference between true temperature and indicated temperature when there is fouling or buildup

💭 Think About

• What happens to heat transfer to the thermocouple if a layer of carbon builds up on it – does it improve or restrict heat flow? • If the thermocouple receives heat more slowly or less directly, will the instrument tend to indicate a higher or a lower temperature than the actual exhaust temperature? • Which choices are actually about the instrument’s reading versus unrelated engine/exhaust problems?

✅ Before You Answer

• Focus on how fouling/insulation affects the temperature indication, not general engine damage • Eliminate options that don’t directly involve instrument behavior or reading accuracy • Ask: does carbon buildup typically act more like a thermal conductor or a thermal insulator around the hot junction?