Engine internals

Roller finger follower

Transfers cam-lobe motion to the valve.

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

Between each cam lobe and valve in the cylinder head.

How it works

A roller rides on the lobe while one end pivots on a lash adjuster and the other presses the valve stem.

Think of it as

A see-saw that turns a push into a nudge.

Symptoms when it fails

Ticking from the top of the engine may involve followers, adjusters or oil supply.

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 BMW engines add an intermediate lever above the follower to vary intake valve lift.

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.