Question 66 DDE01 - Designated Duty Engineer - Unlimited HP

The Correct Answer is C **Explanation of Option C (Correct):** Option C states: "The governor oil should be drained while the oil is hot and the governor should be flushed with the lightest grade of the same type of oil." 1. **Draining while Hot:** Oil should always be drained while hot (immediately after the engine has been running) because heat lowers the oil's viscosity. Low viscosity allows the oil to flow more easily and carry away suspended contaminants (sludge, wear particles) that might otherwise settle and remain in the governor reservoir or passageways if the oil were drained cold. 2. **Flushing with Lightest Grade:** When flushing a sensitive component like a hydraulic governor, the goal is to remove residual contaminants and old oil thoroughly. Using the lightest (lowest viscosity) grade of the specified oil type ensures maximum penetration and cleaning power through the intricate, narrow internal passages and small orifices (jets, ports) common in governors. A lighter oil flows more freely and is better at carrying away debris than a heavy oil. **Why Other Options Are Incorrect:** * **A) The governor oil should be drained while the oil is hot and the governor should be flushed with the heaviest grade of the same type of oil.** * *Incorrect Flush:* While draining hot is correct, flushing with the heaviest grade is counterproductive. Heavy oil has high viscosity, flows poorly through small passages, and may leave excessive residues, reducing the effectiveness of the flush. * **B) The governor oil should be drained while the oil is cold and the governor should be flushed with the lightest grade of the same type of oil.** * *Incorrect Drain:* Draining cold oil is inefficient because the high viscosity prevents complete removal of suspended contaminants and the oil itself. * **D) The governor oil should be drained while the oil is cold and the governor should be flushed with the heaviest grade of the same type of oil.** * *Incorrect Drain and Flush:* This option combines the two least effective procedures: draining cold (high viscosity, poor contaminant removal) and flushing with heavy oil (poor penetration and cleaning).