Timing belt: when to change it

The timing belt synchronises the crankshaft and camshaft (and sometimes the water pump). A broken belt can seriously damage the engine (cylinder head, pistons). It should be replaced at recommended intervals and not left until visible wear appears.

Intervals: manufacturer and engine type

Each manufacturer gives a mileage and often a time (years): typically 150,000–240,000 km or 6–10 years depending on engine. Some recent diesel or petrol engines have longer intervals; others (older or sporty) shorter. Check the service book or handbook; if in doubt, have it checked by a professional.

Signs of wear (often late)

A worn belt may produce a whine on start-up or acceleration, rough idle or timing drift (engine running poorly). These signs often appear when the belt is already very worn: do not wait to replace it if the interval has been exceeded.

Risks if it breaks

On an interference engine (most modern engines), a broken timing belt causes pistons and valves to get out of sync: collision possible, cylinder head or piston damaged. Repair often exceeds €2,000–5,000 and more. Preventive replacement at recommended intervals is much cheaper.

Order of magnitude for costs

Belt + idlers + tensioner (timing kit) replacement: about €400–1,200 depending on vehicle (parts and labour). If the water pump is driven by the same belt, it is often changed at the same time (about €100–300 extra). My Auto Check-up helps you estimate maintenance costs and prepare your visit.