Question 17 QMED01 - Junior Engineer

The Correct Answer is A **Why Option A ("the pressure drop across the filter") is correct:** A filter's primary function is to trap contaminants. As the filter element accumulates dirt and particles (becomes "dirty"), the restriction to oil flow increases. This increased restriction directly results in a higher differential pressure (pressure drop) measured across the filter housing—meaning the pressure before the filter is significantly higher than the pressure after it. Monitoring this pressure drop is the standard and most reliable operational method for determining when a filter element is nearing the end of its useful life and requires replacement due to clogging. Many modern engines and systems use a differential pressure switch or gauge specifically for this diagnostic purpose. **Why the other options are incorrect:** * **B) high lube oil sump temperature:** While excessive friction or a major restriction in the oil system *could* potentially contribute to slightly higher oil temperatures, a high lube oil sump temperature is generally indicative of engine overheating (e.g., cooling system failure, overloading, combustion issues) and is not a reliable or specific indicator of a clogged oil filter element. * **C) decrease in oil viscosity from the filter:** Oil viscosity degradation (decrease) is primarily caused by shearing, overheating, fuel dilution, or water contamination, and occurs throughout the entire oil charge (the sump). A dirty filter element itself does not cause a *decrease* in the oil's viscosity. * **D) visual inspection of the elements:** While a visual inspection can confirm that an element is dirty *after* it has been removed, this is a reactive maintenance step. Operational detection (the "best" method for detection while the engine is running or planning maintenance) relies on monitoring system parameters. A visual inspection cannot be performed while the engine is running and the filter is installed, making it an impractical method for real-time or preventative detection.