The timing cover sits at the front of the engine and protects the timing belt or chain. This system keeps the camshaft and crankshaft synchronized so the valves open and close at the correct time as the pistons move.

The cover also helps keep dirt out and, on chain-driven engines, seals lubricating oil inside.

Main job: Protects the parts that keep the engine perfectly timed.

The valve cover sits on top of the cylinder head and protects the camshaft and valve train from dirt and moisture. It also seals engine oil inside the engine, preventing leaks while allowing oil to lubricate the moving parts beneath.

Many valve covers also provide mounting points for components such as the oil filler cap, ignition coils, or the PCV system.

Main job: Protects the valve train and keeps engine oil sealed inside.

The cylinder head sits on top of the engine block and seals the combustion chambers. It houses important components such as the valves, camshaft, spark plugs (or glow plugs on diesel engines), and fuel injectors on many modern engines.

Air enters, exhaust gases leave, and combustion takes place beneath the cylinder head, making it one of the engine's most important components.

Main job: Seals the cylinders and controls the flow of air, fuel, and exhaust gases.

The engine block is the main body of the engine and provides the foundation for almost every major component. It contains the cylinders where the pistons move up and down, along with oil galleries and coolant passages that help lubricate and cool the engine.

The cylinder head bolts to the top of the block, while the crankshaft is supported inside it.

Main job: Supports the engine's moving parts and houses the cylinders where power is produced.

The oil pan, also called the sump, is bolted to the bottom of the engine block and stores the engine's supply of oil. As the engine runs, oil drains back into the pan before being pumped around the engine again to lubricate and cool moving parts.

The oil pan also provides a mounting point for the oil drain plug, making routine oil changes possible.

Main job: Stores engine oil and supplies it to the lubrication system.