Operating inside the engine block and bathed in engine oil, this chain keeps the valve timing in perfect sync with the piston strokes. Unlike rubber belts, these chains are designed to last the lifetime of the vehicle, though they rely heavily on hydraulic tensioners and plastic guides. Poor oil maintenance can cause the chain to stretch or the guides to fail, leading to engine rattle and skipped timing.
I can hear the timing chain slapping against the cover on cold starts, so the tensioner is definitely shot.
Do not mix it up with
- Timing belt: A timing chain is an internally lubricated metal chain, while a timing belt is a dry rubber belt mounted on the outside of the engine block.
Related terms
Timing belt
A reinforced rubber belt that synchronizes the rotation of the crankshaft and the camshafts.
Cylinder head
This cast metal component bolts to the top of the engine block to seal the combustion chambers.
Overhead cam
A valvetrain layout where the camshaft is located in the cylinder head above the combustion chamber.