🔍 Key Concepts

• Four-stroke vs two-stroke timing relationship between camshaft and crankshaft • How piston cooling by lubricating oil is usually shown in a sectional drawing • Visual differences between wet cylinder liners and dry liners in an engine cross section

💭 Think About

• From basic engine theory, what is the normal speed relationship between the camshaft and crankshaft in a four-stroke diesel? Use that to judge option A. • Look closely under the pistons in the crankcase area: do you see any nozzles or passages that would direct oil up to the underside of the piston crown, as described in option B? • Examine the cylinder walls: do the cylinder sleeves appear to be directly surrounded by coolant (with sealing rings) or are they solid with the block, which would affect whether option C is accurate?

✅ Before You Answer

• Confirm whether the illustration clearly shows a four-stroke valve arrangement (intake/exhaust valves and cam-driven mechanism). • Identify any oil spray jets or passages aimed at the underside of the piston crown before deciding about piston cooling. • Trace the outline of the cylinder liner and water jacket to see if coolant contacts the liner directly (wet liner) or if the liner is separated from the coolant by block material (dry liner).