Engine internals

Hydraulic lash adjuster

Keeps valve clearance at zero automatically.

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

Under the pivot end of each finger follower.

How it works

Engine oil fills a small plunger chamber, taking up slack so the valvetrain stays quiet without manual adjustment.

Think of it as

A self-adjusting doorstop that always fits the gap.

Symptoms when it fails

A ticking noise after a cold start can come from adjusters that have drained, though it should clear quickly.

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

Classic BMW M engines such as the S14 used solid lifters set by hand; most later BMW engines use hydraulic adjusters.

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.