How often should a timing belt be replaced?

Most manufacturers recommend replacing the timing belt every 40,000-100,000 miles or every 4-6 years, whichever comes first. The exact interval varies by make and model. Common intervals are: many VW/Audi 4-cylinder engines at 80,000 miles, Ford at 100,000 miles, and some Honda models at 60,000 miles. Always check your specific model.

What is an interference engine?

An interference engine is one where the valves and pistons occupy the same space in the cylinder at different times. If the timing belt breaks, the pistons hit the open valves, causing bent valves, damaged pistons, and potentially a destroyed engine. Most modern engines are interference type. Repair costs can exceed the car's value.

What happens if a timing belt breaks?

On an interference engine, a broken timing belt typically bends valves and damages pistons, requiring a complete engine rebuild or replacement (£2,000-£5,000+). On a non-interference engine, the engine simply stops and won't restart, but internal damage is unlikely. Either way, you will be stranded.

Should I replace the water pump at the same time?

Yes, almost always. The water pump is driven by the timing belt on most cars, and replacing it at the same time adds only £30-£80 in parts (the labour is already done). If the water pump fails later, you need to pay for the entire timing belt job again to access it.

Does my car have a timing belt or timing chain?

Some engines use a timing chain instead of a belt. Chains typically last the life of the engine (200,000+ miles) and do not need routine replacement, though they can stretch over time. Check your owner's manual. Generally, many modern BMW, Mercedes, and some newer Vauxhall engines use chains.

CarCalcs

Timing Belt Calculator — When Is Replacement Due?

Calculate when your timing belt is due for replacement based on mileage and age intervals.

Current Mileage

Last Belt Change (mileage)

Years Since Last Change

Manufacturer Interval (miles)

Manufacturer Interval (years)

Engine Type

Annual Mileage

How We Calculate This

How It Works

The timing belt replacement is based on two intervals — whichever comes first:

Mileage interval: Due at = Last change mileage + Interval miles
Time interval: Due at = Last change date + Interval years

Why Both Matter

Rubber degrades over time even without use. A timing belt on a low-mileage car that has never been changed may look fine but could be brittle and ready to snap. Time-based replacement is just as important as mileage-based.

What to Replace

A complete timing belt job should include: timing belt, tensioner(s), idler pulley(s), and water pump. Some cars also have auxiliary belts that should be done at the same time.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Actual figures may vary based on driving conditions, vehicle specifications, and other factors.