Symptoms
- Approaching or past the mileage listed in the manual for timing belt replacement
- No record of it ever being changed on a used car
- Car has an interference engine (check your manual or ask a shop)
Likely causes
- CommonInterval reached through normal wearRubber timing belts degrade with age and mileage regardless of how well the car runs.
- CommonUnknown service history on a used carWithout records, you can't assume a previous owner did this service even if the engine runs fine.
- PossibleConfusion with a timing chain (which usually doesn't need scheduled replacement)Not all engines have a timing belt; many modern engines use a timing chain instead.
What to do
- Check your owner's manual or a VIN lookup to confirm whether your engine uses a timing belt or a timing chain, since they're maintained very differently.
- If it's a belt, find the manufacturer's replacement interval, usually listed in miles and years.
- On a used car with no service records, assume the belt has not been changed unless you can verify otherwise.
- Ask whether your engine is an 'interference' design, where a snapped belt can cause the pistons and valves to collide and cause major damage.
- Have the timing belt replaced proactively before or at the interval, along with the water pump if it's driven by the same belt (commonly recommended together).
- Keep the receipt and mileage noted, since this is an expensive service worth having documented, especially if you sell the car later.
Tools and parts
Timing belt kit including water pump, as recommended for your engineSearch: “timing belt kit for [your car year make model]”
When to call a pro
This is typically a job for a professional shop given the precision timing required; a mistake can cause the same damage the maintenance is meant to prevent.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.