Engine internals

Cylinder-head cover

Seals the top of the engine around the valve gear.

Drag to turn it Open in the 3D lab
Where it sits

Above the cylinder head, often under a cosmetic engine cover.

How it works

Its gasket seals oil inside; some designs also integrate crankcase-ventilation passages or hardware.

Think of it as

A protective lid on a moving mechanism.

Symptoms when it fails

Oil smell, visible seepage or ventilation faults may involve the cover, gasket or connected hoses.

Lifespan

Usually condition-based rather than a routine replacement. Lubrication, overheating and the exact engine affect wear.

Repair cost

Internal-engine work is usually labor-intensive. Diagnosis and the engine code determine the repair scope.

The BMW angle

A BMW’s decorative engine cover and its oil-sealing cylinder-head cover are separate parts.

Used in

BMW petrol and diesel engines; petrol-only systems are identified individually.

Sources
Same system

Engine internals

Engine blockHolds the cylinders and supports the engine’s rotating parts.Cylinder headCloses the cylinders and carries the valves that control breathing.Cylinder-head gasketSeals combustion pressure, oil and coolant between the block and head.PistonReceives combustion force and moves up and down inside a cylinder.Piston ringsSeal combustion gas and control the oil film on cylinder walls.Connecting rodTransfers piston force to the crankshaft.CrankshaftTurns the pistons’ back-and-forth motion into rotation.Crankshaft main bearingSupports the crankshaft on a controlled film of oil.