Engine internals

Valvetronic valve-lift system

Varies how far the intake valves open to control airflow.

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

In the cylinder-head intake valve gear on equipped petrol engines.

How it works

An eccentric mechanism changes the motion delivered to intake valves; it works alongside cam-timing control.

Think of it as

Opening a door a little or a lot to regulate a crowd.

Symptoms when it fails

Starting difficulty, reduced-power warnings or adaptation faults can have electrical or mechanical causes.

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

Valvetronic adjusts valve lift, while VANOS adjusts timing; equipped BMW engines can use both.

Used in

Equipped BMW petrol engines, including the B38 family. It is not present on every BMW petrol engine.

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.