We recommend changing the belt, pulleys and water pump every 5 years or 50,000 miles (whichever comes first). The cost depends on two factors: who’s doing the work and the make and model of your car. It'll likely cost between £200 and £1000, depending on hours of labour, cost of labour, cost of parts etc. Typical cambelt replacement costs are in the region of £300 to £400 — but the most substantial part of your bill will generally be labour costs. These are high because changing a cambelt involves taking apart the engine block and putting it back together again, which can take a number of hours.