🔍 Key Concepts

• Indicator cocks on a diesel engine and what they are used for • Effects of water or liquid inside an engine cylinder when starting • What systems are actually being tested when you "turn the engine on air" or roll it over slowly

💭 Think About

• Think about what could happen inside a cylinder if it contained an incompressible fluid when the piston comes up on the compression stroke. • Ask yourself which option is directly related to the purpose of opening the indicator cocks themselves, not just any common pre-start check. • Consider which of these actions would prevent serious mechanical damage during the first few revolutions of the engine.

✅ Before You Answer

• Verify the primary function of cylinder indicator cocks (are they mainly for testing starting systems, removing jacket water air, checking lube oil, or checking cylinder contents?). • Check which of the listed choices is connected to preventing hydraulic lock or damage from liquid in the cylinder. • Confirm that jacket water and lube oil systems have their own specific pre-start checks that do not require opening indicator cocks.