Which of the following can cause low oil pressure?

Which of the following can cause low oil pressure?

• A. Excessive bearing clearance
• B. Clogged air filter
• C. Worn spark plugs
• D. Low coolant level

Answer: (A)

Oil pressure is driven by the oil pump and how easily oil can stay in the lubricating passages. When bearing clearance is excessive, the gap between the crankshaft journal and the bearing is wider. That larger clearance allows more oil to leak back into the sump rather than staying in the main galleries to build pressure. The result is a drop in oil pressure, especially when the engine is hot or idling, and it can lead to insufficient lubrication and accelerated wear. The other options don’t directly affect oil pressure. A clogged air filter changes air entering the engine and its combustion, not the lubrication system. Worn spark plugs impact ignition and combustion, not oil pressure. A low coolant level affects cooling, not the oil pressure.

Oil pressure is driven by the oil pump and how easily oil can stay in the lubricating passages. When bearing clearance is excessive, the gap between the crankshaft journal and the bearing is wider. That larger clearance allows more oil to leak back into the sump rather than staying in the main galleries to build pressure. The result is a drop in oil pressure, especially when the engine is hot or idling, and it can lead to insufficient lubrication and accelerated wear.

The other options don’t directly affect oil pressure. A clogged air filter changes air entering the engine and its combustion, not the lubrication system. Worn spark plugs impact ignition and combustion, not oil pressure. A low coolant level affects cooling, not the oil pressure.