All of the following are in the engine block EXCEPT:

• A. Heater Core
• B. Cylinders
• C. Main bearings
• D. Oil passages

Answer: (A)

The engine block houses the moving and lubricated parts of the engine and includes internal channels for oil flow. Cylinders are built into the block where the pistons move, main bearings support the crankshaft inside the block, and oil passages are the internal routes that carry lubrication to those moving parts. The heater core, however, is not inside the engine block. It’s part of the vehicle’s HVAC system and is located in the dash/air-duct area; it uses hot engine coolant that flows through hoses to heat the cabin air. So the heater core is the item that does not belong to the engine block.