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. Before releasing a fixed CO2 system into a machinery space, personnel must:

• A.Open all ventilation to the space
• B.Evacuate the space, account for all personnel, and shut down ventilation and fuel✓
• C.Increase the fuel oil flow
• D.Leave the watertight doors open

Why: CO2 smothers fire by displacing oxygen and is lethal to people. The space must be evacuated and a head count taken, then ventilation and fuel secured and the space sealed before discharge.

5. Boiler 'blowdown' (surface or bottom) is performed to:

• A.Raise steam temperature
• B.Remove accumulated dissolved solids and sludge to control water quality✓
• C.Refill the boiler quickly
• D.Test the superheater

Why: As water boils off, solids concentrate. Blowdown discharges some high-solids water (and bottom sludge) so the remaining water stays within treatment limits, preventing scale and carryover.