🔍 Key Concepts

• Most small marine engine lube oil systems must supply oil at a steady pressure to bearings and moving parts. • Think about how suction from a sump and delivery through narrow oil passages affects the type of pump needed. • Compare how centrifugal vs. positive displacement pumps behave when system resistance (back pressure) changes.

💭 Think About

• Which pump type is best at delivering a fairly constant flow and pressure even if the engine speed or line resistance changes? • If the lube oil passages become more restricted (thicker oil, colder temperature), which pump type will still move oil reliably without easily losing its flow? • Which of the listed pump types is commonly used for precise lubrication rather than just bulk transfer of liquids?

✅ Before You Answer

• Recall that centrifugal pumps lose flow quickly as discharge pressure increases; does that fit a critical lube system? • Consider whether diaphragm or eductor pumps are normally used for engine lubrication, or for other purposes like bilge/chemical transfer. • Make sure the pump type you choose is one that is typically used for engine lube oil service on small marine diesels, not just for general pumping.