Engine internals

Exhaust valve

Lets burned gas leave the cylinder.

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

In the cylinder head at each exhaust port.

How it works

Its head and seat endure hot exhaust flow, then seal the cylinder for the next cycle.

Think of it as

The exit door after the work is done.

Symptoms when it fails

Compression loss, overheating or a misfire can involve valve sealing.

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

Exhaust valve hardware is chosen for each BMW engine’s thermal load, especially in turbocharged applications.

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.