Camshafts
The camshaft is the rotating shaft whose lobes open the engine’s valves in the correct sequence and for the correct duration, timed to the crankshaft.
What it does
Driven by the timing chain or belt at half crankshaft speed on a four-stroke engine, the cam lobes act on followers or rockers to push the valves open. Valve springs close them again.
Signs a camshaft is failing
- A ticking or tapping from the top of the engine
- Rough running or misfire on specific cylinders
- Loss of power across the rev range
- Camshaft correlation fault codes
When to replace them
Not a scheduled item. Replaced after lobe wear, oil starvation damage, or as part of a rebuild.
What to confirm before ordering
Have these ready and the counter can usually confirm the part in under a minute.
- Engine code, and whether the engine is a single or twin cam design
- Inlet or exhaust camshaft, since they differ
- Whether variable valve timing hardware is fitted
- The condition of the followers, which usually need replacing alongside
Camshafts questions
What causes camshaft lobe wear?
Oil starvation is the usual cause, whether from extended service intervals, a low oil level, or a blocked oil feed. The lobe and its follower wear together, which is why both are replaced.
Do the followers need replacing with the camshaft?
Yes. A worn follower will destroy a new lobe quickly, because the two surfaces have bedded to each other and the wear pattern will not match.