Timing Belt
What it is
The timing belt synchronises the crankshaft and camshaft so the valves open and close at the right moment. Many engines use a timing chain instead, which usually lasts longer.
What it does
It keeps engine timing precise. A worn belt can slip a tooth (causing rough running or a correlation code); on an interference engine, a snapped timing belt lets pistons hit valves and can wreck the engine — which is why it is a strict interval item.
Symptoms of failure
- Ticking or slapping noise from the timing cover
- Rough running or a cam/crank correlation code if it slips
- Oil leak from the cam/crank seals nearby
- Engine will not start (snapped belt)
- Severe damage on interference engines if it breaks
Which vehicles need it
Many petrol and diesel engines (others use a chain). Interference engines make timely replacement critical.
Replacement cost
| DIY (part only) | $50–$200 |
|---|---|
| At a shop (parts + labor) | $500–$1,100 |
| Replacement interval | Typically every 60,000–105,000 miles (100,000–168,000 km) — follow the manual exactly. |
| DIY difficulty | Hard / Professional — precise timing required; do the water pump and tensioner at the same time |
| Recommended brands | Gates, Continental, Aisin, OEM |
Where to buy the part
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Frequently asked questions
What happens if my timing belt breaks?
On an interference engine, the pistons can hit the open valves and cause major internal damage. On a non-interference engine the car just stalls. Either way, replace the belt at the recommended interval — do not push your luck.
Should I replace the water pump with the timing belt?
Yes, on belt-driven water pumps. The pump sits behind the belt, so doing both together saves a second teardown and avoids a pump failure ruining a fresh belt.