Engineering Practice Questions

1. In a four-stroke-cycle diesel engine, the events occur in which order?

• A.Intake, power, compression, exhaust
• B.Intake, compression, power, exhaust✓
• C.Compression, intake, exhaust, power
• D.Power, exhaust, intake, compression

Why: A four-stroke cycle completes one power event every two crankshaft revolutions in the order intake, compression, power (combustion/expansion), then exhaust.

2. According to good engineering practice, diesel fuel filters should be changed or serviced based on:

• A.The manufacturer's recommended service intervals AND whenever a pressure differential across the filter exceeds the specified limit✓
• B.Only when engine performance degrades noticeably, such as loss of power or black smoke
• C.A fixed calendar interval of every six months regardless of operating hours or pressure drop
• D.Only when the fuel in the day tank shows visible sediment or discoloration

Why: Fuel filters should be changed per the manufacturer's hour-based service schedule and whenever the pressure differential (measured between inlet and outlet) reaches the maximum specified value, indicating the filter media is becoming restricted and starving the injection system of fuel.

3. An anti-siphon valve (siphon break) on a marine toilet (head) discharge line is installed to:

• A.Prevent seawater from siphoning back into the toilet bowl and flooding the vessel when the vessel heels or the discharge outlet goes below the waterline✓
• B.Prevent sewage from being discharged into waters protected under 33 CFR Part 159
• C.Regulate the flow rate of discharge to protect the macerator pump
• D.Allow the holding tank to vent overboard without releasing odor into the cabin

Why: Without an anti-siphon valve in the head discharge line, heeling or wave action can submerge the discharge outlet and establish a siphon that draws seawater continuously back into the vessel through the toilet; the siphon break admits air to stop this flooding mechanism.

4. Under MARPOL Annex I, machinery-space bilge water discharged from a ship underway must generally pass through equipment ensuring the oil content does not exceed:

• A.100 ppm
• B.50 ppm
• C.15 ppm✓
• D.1 percent

Why: Oily bilge water must be processed through an oily-water separator with a 15-ppm bilge alarm; the effluent oil content must not exceed 15 parts per million for discharge outside special areas while proceeding en route.

5. Priming or carryover in a boiler refers to:

• A.Steam leaving the drum too dry
• B.Water/solids being carried over with the steam into the line✓
• C.Loss of feedwater pressure
• D.Excess combustion air

Why: Carryover/priming is water and dissolved solids carried out with the steam — caused by high water level, high solids, or sudden load swings. It can damage the turbine and contaminate downstream equipment.