Marine Diesel Engineering Exam for Small Vessel Second Engineer Certificate

Overlap refers to the period during which both the intake and exhaust valves are open at the same time, allowing a small amount of the fresh intake charge to escape back into the exhaust system.

Piston ring end clearance is necessary to allow for thermal expansion of the rings during engine operation, preventing the rings from binding in the ring grooves.

To manually test the set points on a diesel engine lubricating oil low pressure alarm and shut down using a pressure calibrator, the procedure would involve:1. Isolating the oil pressure sensor from the engine's lubricating oil system.2. Connecting a pressure calibrator to the sensor.3. Incrementally decreasing the pressure while monitoring the alarm and shut down set points.4. Verifying that the alarm activates at the correct low pressure set point, and the engine shuts down at the appropriate lower pressure set point.

A typical distillate fuel supply system for a diesel engine would include the following components and safety devices:1. Fuel tank2. Fuel filters3. Fuel pump4. Fuel lines5. Fuel injectors6. Fuel pressure regulator7. Fuel return line8. Fuel level sensor9. Fuel leakage detection system10. Fuel shut-off valveThe safety devices in this system, such as the fuel level sensor, leakage detection system, and shut-off valve, help prevent fuel spills and ensure the safe operation of the diesel engine.

Three desirable properties of piston rings are:1. Good sealing ability to prevent leakage of combustion gases past the piston2. Resistance to wear and heat3. Flexibility to allow for thermal expansion and maintain a tight fit in the ring grooves.

The common materials used for piston rings include:1. Cast iron2. Steel3. Chromium-plated steel4. Molybdenum-coated steel5. Composite materials (e.g., carbon-fiber reinforced polymers)

The three common types of piston ring ends are:1. Butt joint: The ring ends meet in a straight, square joint.2. Stepped joint: The ring ends have a stepped profile, with one end overlapping the other.3. Lapped joint: The ring ends overlap each other, forming a tapered joint.

It is a measure of the ignition quality of diesel fuel.

It is the amount of heat produced by the complete combustion of a specific quantity of fuel.

Density refers to the mass of a substance per unit volume.

Viscosity is the measure of a fluid's resistance to flow.

A coalescer filter is designed to combine small droplets of water into larger ones for easier removal.

By regular monitoring, testing, and changing of the oil as needed.

By observing abnormal air consumption or performance issues during engine start.

The faulty valve should be isolated and replaced during scheduled maintenance.

Possible causes include wear, corrosion, improper sealing, and inadequate maintenance.

Ensure the engine is cool, drain coolant, disconnect batteries, and wear appropriate safety gear.

The magnetic filter helps to remove ferrous particles from the oil, preventing damage to components.

A smooth surface finish reduces friction, wear, and noise while increasing efficiency.

A flexible coupling accommodates misalignment and reduces vibration transmission between the engine and gearbox.