MDE 16 Q3

Correct Answer: D) By monitoring for a hissing sound near the air start valve manifold

Explanation: A leaking air start valve may produce a hissing sound due to the escape of compressed air, which can often be detected near the air start valve manifold while the engine is running.

• Correct Answer: B) Replace the air start valve with a new one

Explanation:
If the valve continues to leak even after cleaning and inspection, it likely means the valve or seating is damaged beyond repair. In this case, the safest course of action is to replace the valve to restore the engine’s integrity. Applying lubricant (A) or reducing the engine load (D) would not solve the issue and could lead to further complications. Installing a temporary bypass (C) is not recommended as it doesn't address the root cause and can compromise engine safety.

• Correct Answer: B) Inspect the valve and seating area for damage or debris

Explanation:
After shutting down the engine, the next logical step is to inspect the air start valve and its seating area. The leakage could be caused by damage to the valve or debris preventing it from sealing properly. This inspection will help determine the cause and guide the appropriate repair. Immediate replacement (A) might be unnecessary if the issue can be resolved by cleaning, and cleaning the valve while still installed (C) wouldn’t be thorough. Re-starting the engine (D) without addressing the issue could cause further damage.

• Correct Answer: B) Clean the valve and seating area, and then reinstall

Explanation:
If debris is the issue, the appropriate action is to clean both the valve and the seating area to ensure a proper seal. Replacing the valve (A) may not be necessary if cleaning resolves the issue, and increasing air pressure (C) could cause more damage. Blocking off the air supply (D) might temporarily stop the leakage but is not a permanent fix and could lead to further complications.

Explanation:
When a cylinder air start valve is leaking, it poses a significant risk of air leakage into the cylinder, which can cause serious engine damage or even an explosion if left unchecked. The immediate response is to shut down the engine to prevent any further damage and isolate the affected cylinder to stop the air supply to it. Continuing normal operation (A) or increasing engine speed (B) would exacerbate the problem, and manually operating the valve (D) would not address the underlying issue safely.