Practice Test Geeks(310t) Truck and Coach Technician Certification Practice Test
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Engine and Fuel Systems Flashcards

7 cards from real 310T 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 and Fuel Systems flashcards as text

  1. Which diesel engine emission control system recirculates exhaust gases back into the intake to reduce NOx emissions?

    Answer: Exhaust Gas Recirculation (EGR)

    EGR reduces peak combustion temperatures by diluting the intake charge with inert exhaust gas, which lowers the formation of NOx.

  2. During a diesel injector balance rate test, one injector shows a significantly higher fuel delivery than the others. This indicates the injector is:

    Answer: Delivering too much fuel, possibly stuck open or leaking

    A high balance rate means the ECM is commanding more fuel to compensate, indicating the injector is delivering too little—not too much—fuel on its own.

  3. What causes diesel engine 'cavitation erosion' damage to cylinder liners?

    Answer: Coolant pressure fluctuations causing vapor bubble collapse on the liner exterior

    Cavitation erosion occurs when coolant pressure waves cause vapor bubbles to form and implode against the wet cylinder liner's outer surface.

  4. A technician is diagnosing a no-start condition on a diesel. Fuel pressure is correct but the engine will not start. What should be checked next?

    Answer: Glow plug or grid heater operation

    If fuel pressure is adequate and the engine won't start in cold or normal conditions, faulty glow plugs or a grid heater are a primary suspect for diesels.

  5. What is the function of the intake throttle valve (ITV) on a modern diesel engine equipped with EGR?

    Answer: Creates intake manifold vacuum to draw EGR gases into the intake

    The intake throttle valve partially restricts airflow to create a pressure differential that helps pull EGR gases into the intake manifold.

  6. When should diesel engine valve lash (valve clearance) be adjusted?

    Answer: Only when the engine is cold and at TDC for each cylinder

    Valve lash must be set with the engine cold and the piston at TDC compression stroke to ensure accurate clearance per manufacturer specification.

  7. A diesel engine's oil analysis report shows a high silicon content. What does this most likely indicate?

    Answer: Air filter failure allowing dirt ingestion

    Silicon is the primary indicator of dirt contamination, most often caused by a compromised air filtration system allowing abrasive particles into the engine.