Which of the following identifies a symptom of a defective oil pump relief valve during operation?

Which of the following identifies a symptom of a defective oil pump relief valve during operation?

• A. Oil pressure is excessively low at all speeds.
• B. Oil pressure remains within spec under all conditions.
• C. The relief valve vents oil back to the sump without addressing pressure.
• D. The relief valve fails to open at the specified pressure, causing oil pressure to rise beyond specs.

Answer: (D)

The relief valve’s job is to keep oil pressure from getting too high by routing excess oil back to the sump once the set pressure is reached. If the valve fails to open at the specified pressure, the pump keeps pushing oil and pressure climbs beyond the limit, producing a high-pressure condition that signals a defective relief valve. This is the clearest symptom because it shows the regulator isn’t doing its job of capping pressure. If oil pressure were excessively low at all speeds, that points to the pump’s ability to generate pressure or oil supply issues rather than the relief valve failing to open. If pressure remains within spec under all conditions, everything is functioning normally. If the relief valve opened too early or leaks back to the sump, it would prevent pressure from building and would more likely produce low pressure, not the excessively high pressure described in the symptom.

The relief valve’s job is to keep oil pressure from getting too high by routing excess oil back to the sump once the set pressure is reached. If the valve fails to open at the specified pressure, the pump keeps pushing oil and pressure climbs beyond the limit, producing a high-pressure condition that signals a defective relief valve. This is the clearest symptom because it shows the regulator isn’t doing its job of capping pressure.

If oil pressure were excessively low at all speeds, that points to the pump’s ability to generate pressure or oil supply issues rather than the relief valve failing to open. If pressure remains within spec under all conditions, everything is functioning normally. If the relief valve opened too early or leaks back to the sump, it would prevent pressure from building and would more likely produce low pressure, not the excessively high pressure described in the symptom.