Engine Performance & Diagnostics Flashcards
7 cards from real LEC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Engine Performance & Diagnostics flashcards as text
What does an abnormally high fuel consumption rate with normal horsepower output suggest about a diesel locomotive?
Answer: Fuel injectors are delivering more fuel than needed for the power being produced, indicating poor combustion efficiency
Higher fuel use for the same output means combustion efficiency has decreased, often from injector wear, poor fuel quality, or timing issues wasting fuel energy.
A locomotive engineer reports that the engine starts normally but loses power progressively over a 2-hour run. The FIRST system to check is:
Answer: Fuel system for gradual blockage in fuel filters or air entrainment in fuel lines
Progressive power loss over time often indicates a fuel delivery issue such as a fuel filter progressively plugging or air entering the fuel system as temperature rises.
What is the significance of a 'lube oil dilution' finding during an oil analysis on a locomotive diesel engine?
Answer: It indicates fuel or coolant contamination of the oil, increasing wear risk and requiring investigation
Oil dilution means a foreign fluid (usually fuel or coolant) is contaminating the lube oil, reducing its viscosity and film strength, which increases engine wear risk.
On a GE locomotive with FIRE (Full Independent Redundancy Equipment) engine protection, which action occurs when a critical protection parameter is exceeded?
Answer: The system automatically reduces engine load and may initiate engine shutdown depending on severity
GE's engine protection systems automatically load-reduce and can initiate shutdown for critical parameters, though the specific response depends on which parameter is violated.
After a long downgrade using dynamic braking, an engineer notices reduced dynamic brake effectiveness. The MOST likely cause is:
Answer: Traction motor armatures have overheated, causing increased resistance and reduced braking force
Prolonged dynamic braking generates heat in traction motors; when they overheat, protection systems reduce braking force to prevent motor damage.
Which instrument reading confirms that a diesel locomotive's turbocharger is functioning correctly at full throttle?
Answer: Intake manifold boost pressure above the minimum specified value for that throttle notch
Adequate intake manifold boost pressure at full throttle confirms the turbocharger is compressing intake air to the level required for full engine output.
A locomotive diesel engine exhibits hard starting in cold weather despite a functioning starting motor. What should be checked FIRST?
Answer: Engine coolant preheater function and glow plug or starting aid system operation
Cold-start difficulty with a good starter usually points to inadequate intake air heating or coolant preheating, as diesel engines need sufficient temperature for compression ignition.