Question 181Motor Plants - QMED

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In a diesel engine lube oil cooler, with sea water cooling the lubricating oil, what statement is true?

AThe lube oil pressure is always kept higher than the sea water pressure, and in case of a lube oil cooler leak, the lube oil sump level will decrease.
BThe sea water pressure is always kept higher than the lube oil pressure, and in case of a lube oil cooler leak, the lube oil sump level will increase.
CThe sea water pressure is always kept higher than the lube oil pressure, and in case of a lube oil cooler leak, the lube oil sump level will decrease.
DThe lube oil pressure is always kept higher than the sea water pressure, and in case of a lube oil cooler leak, the lube oil sump level will increase.
AI Explanation

The correct answer is A. In a diesel engine lube oil cooler with sea water cooling the lubricating oil, the lube oil pressure is always kept higher than the sea water pressure. This is to ensure that in case of a lube oil cooler leak, the lube oil will leak into the sea water system rather than the sea water entering the lube oil system. If the sea water were to enter the lube oil system, it could contaminate the oil and cause damage to the engine. Therefore, if there is a lube oil cooler leak, the lube oil sump level will decrease as the lube oil is lost to the sea water system. The other options are incorrect because they either have the pressure relationships reversed or the effect on the lube oil sump level incorrect.

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