Engine
Timing Belt / Chain
The timing belt or chain keeps the crankshaft and camshaft synchronized for correct valve timing.
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What it does
- Drives the camshaft(s) from the crankshaft
- On many engines also drives the water pump
- Keeps the valves and pistons in sync
When it fails
- Squealing from under the timing cover
- Camshaft codes (P0340)
- Engine suddenly stops and will not restart (broken belt)
- Oil leaks from the cover
How to diagnose
- Check belt for cracks, glaze or fraying
- Check tensioner play
- Verify timing marks align
Maintenance
- Replace on the manufacturer’s schedule (often 60k–120k km)
- Always replace belt, tensioner and water pump together
- A broken timing belt on an interference engine means engine damage
Use the diagnosis order. When a part fails, confirm each hypothesis with measurements before replacing anything — codes and symptoms overlap.
Related part
Water Pump
The water pump circulates coolant through the engine, radiator and heater core.