ABYC Diesel Practice Exam

During a sea trial with an owner complaining of low power, what measurements are critical to diagnose the issue?

1. Oil pressure and fuel flow

2. Exhaust gas temperature and boost pressure

3. Intake air temperature and fuel viscosity

4. Battery voltage and crank speed

The correct answer is: Exhaust gas temperature and boost pressure

Measuring exhaust gas temperature and boost pressure is critical in diagnosing low power issues during a sea trial. The exhaust gas temperature provides insight into engine combustion efficiency. An unusually high or low temperature could indicate problems such as incomplete combustion, which might be caused by restricted air intake, incorrect fuel delivery, or issues with the turbocharger if equipped. Boost pressure measurements are essential for turbocharged engines as they directly relate to the engine’s ability to produce power. Low boost pressure may indicate turbocharger failure, leaks in the intake system, or problems with the wastegate, which can result in insufficient power output. Thus, focusing on these two parameters gives a clear picture of the engine's performance regarding air-fuel mixture management and combustion efficiency, which are key contributors to overall power delivery.