Engine internals

Timing chain

Keeps crankshaft and camshaft movement synchronized.

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

Inside the timing cover; front or rear location depends on engine.

How it works

Sprockets, guides and a tensioning system maintain the designed timing relationship.

Think of it as

A chain linking two clocks so they stay in step.

Symptoms when it fails

Rattle or timing correlation faults may involve chain wear, tension or lubrication.

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

BMW engines do not all share the same timing-chain arrangement; access and service procedures differ markedly.

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.