Camshafts: The Rotating Shaft That Times the Valves

The camshaft is the rotating shaft inside the cylinder head (or, on older designs, in the engine block) that opens and closes the intake and exhaust valves. Most modern engines have two camshafts (DOHC — Dual Overhead Cam) — one for intake valves, one for exhaust — each turning at half engine speed and lifting the valves through the lifters and rocker arms.

How camshafts wear

The lobes of the camshaft — the egg-shaped projections that lift the valves — wear at the contact surface where they ride on the cam follower or hydraulic lifter. Wear is usually slow but accelerates if oil quality has been poor. Symptoms of cam wear: reduced power, harsh valve-train noise, fault codes for cam timing.

On engines with VVT (Variable Valve Timing — most modern engines), the camshaft includes a cam phaser at the front that allows the ECU to advance or retard cam timing relative to the crank. Phaser failures present as cold-start rattle, sometimes a sudden engine misfire under load.

Replacement

Camshaft replacement requires removing the rocker cover (sometimes the entire cylinder head). The lifters and any related followers should be replaced at the same time — they wear together. New cam followers run with a specific break-in procedure (a few minutes at higher idle to wear in the cam-follower contact).

Brand

OE-equivalent camshafts come from Febi, INA, Vaico for most European applications. Mahle and Bosch supply OE on specific engines. Match by engine code, not just engine size.

Find camshafts for your engine on the Camshaft collection. Camshaft work is rare but specific to the engine when needed.