In a wet sump system, where is oil kept relative to rotating bearings?

• A. An oil level maintained to contact bearings
• B. Constantly full reservoir separate from bearings
• C. Oil is only in a separate reservoir with no contact
• D. Oil is never in contact with the bearings

Answer: (A)

In a wet sump system, the oil is stored in the crankcase around the rotating bearings, so the oil level is kept such that the oil is in contact with the bearings. This arrangement ensures immediate lubrication and cooling as the oil is pumped from the sump through galleries to the bearings and then returned. The idea is that the bearings are submerged in oil, not kept in a separate tank.

The other descriptions refer to different setups. A constantly full external reservoir separated from the bearings describes a dry sump, where oil is stored outside the crankcase and pumped in as needed. Saying the oil is only in a separate reservoir with no contact means there’s no lubrication path to the bearings from the sump, which would fail to lubricate them. Saying the oil is never in contact with the bearings would also not provide lubrication in a wet sump design.