Question 36 MODE01 - Chief MODU Engineer

The Correct Answer is C ### Why Option C (low bearing oil pressure) is correct: A strainer's primary function is to prevent solid contaminants from entering the lubrication system, particularly the fine passages and bearings. If the strainer becomes excessively dirty, the accumulation of debris restricts the flow of oil passing through it. This reduction in flow (due to increased resistance/clogging) means that the lube oil pump has difficulty drawing or pushing the required volume of oil into the system. Since bearing oil pressure is directly dependent on the volume and flow rate of oil delivered by the pump, restricting the inlet or outlet flow severely reduces the pressure available at the bearings. ### Why the other options are incorrect: **A) crankcase dilution:** Crankcase dilution refers to the contamination of the lubricating oil with unburned fuel or water, often caused by poor combustion, worn piston rings, or cooling system leaks. A dirty oil strainer is a filtration problem, not a chemical contamination or leakage issue. **B) excessive oil consumption:** Excessive oil consumption is usually caused by oil leaking past seals, gaskets, or being burned in the combustion chamber (due to worn rings, valve guides, or turbocharger seals). While a clogged strainer can lead to catastrophic failure (which might cause leakage), it does not directly cause the engine to consume oil excessively through normal operational mechanisms. In fact, restricted flow due to clogging often leads to *less* oil moving through the system, not more being consumed. **D) low lube oil temperature:** Low lube oil temperature is typically caused by issues with the cooling system being too efficient (e.g., a faulty oil cooler bypass valve stuck open, or extremely cold ambient conditions). A dirty strainer increases resistance, which tends to generate more heat due to friction (shear forces), potentially leading to slightly higher oil temperatures, not lower ones.