🔍 Key Concepts

• How a pilot-operated main air starting valve works during starting and what should happen to it once the engine is running • What happens to starting air if a valve leaks into a cylinder that is already firing • The difference between changes in temperature, pressure, and line condition (overheating) as indications of a leak

💭 Think About

• Think about where the starting air is physically located and routed when the engine is running normally. If one valve leaks, what part of the system is directly affected? • Consider how a continuous or intermittent flow of high‑pressure air into a hot cylinder would affect nearby components: which part would show a clear, localized symptom? • Ask yourself which of these indicators (exhaust temp change, manifold pressure change, exhaust pressure, air line overheating) would most likely be limited to one cylinder instead of the whole engine.

✅ Before You Answer

• Identify what should happen to the main air starting valve after the engine has started (open or closed?). • Decide which symptom would be local to that cylinder’s starting air circuit rather than affecting the entire exhaust or manifold system. • Confirm which option reflects a direct consequence of air leaking through the starting valve rather than a secondary engine‑performance effect.