Timing belt · 2026
BMW 3 Series timing belt cost
The BMW 3 Series is timing chain, not belt, across virtually every modern engine (petrol and diesel). If you are searching for a 3 Series timing belt you almost certainly want the timing chain, which has no fixed interval but should be replaced if it rattles or stretches. As a guide, if a chain does need replacing, a UK independent garage typically charges £340–£968 for a BMW 3 Series.
Does the BMW 3 Series have a belt or chain?
It depends on the engine. Here's the belt-vs-chain breakdown for the main UK BMW 3 Series engines, with typical manufacturer replacement intervals (always confirm against your own handbook):
| Engine | Type | Interval |
|---|---|---|
320d N47 diesel (2007–2014) Timing chain. N47 chain failure is a well-known issue; the chain is rear-mounted against the bulkhead, making replacement very labour-intensive. Often fails from around 60k miles on poorly serviced cars. | Timing chain | No set interval |
320d / 318d B47 diesel (2014 on) Timing chain, no fixed interval. BMW relocated the chain to the front of the engine, making it more durable and easier to service than the N47. | Timing chain | No set interval |
320i / 328i N20 petrol (2011–2015) Timing chain; N20/N26 are prone to chain guide and tensioner wear, which can cause rattle and in worst cases chain failure. | Timing chain | No set interval |
320i / 330i B48 petrol (2015 on) Timing chain, generally more robust than the N20; no scheduled replacement interval. | Timing chain | No set interval |
325i / 330i N52/N53 six-cylinder petrol Timing chain, no fixed interval; generally regarded as durable. | Timing chain | No set interval |
335i N54/N55 3.0 turbo petrol Timing chain, no scheduled replacement; inspect if rattle develops. | Timing chain | No set interval |
BMW 3 Series timing belt cost
The 3 Series is chain-driven on most engines, so there's no routine cambelt cost. If a worn chain ever needs replacing, expect roughly £340–£968 at a UK independent garage — chains are labour-heavy to access.
Key things to know
- Almost all BMW 3 Series engines use a timing chain, not a belt, so there is no scheduled cambelt change.
- The N47 diesel (2007–2014) is the standout problem engine: a rear-mounted chain that is expensive to access and known to fail.
- The newer B47 diesel and B48 petrol moved the chain forward and improved reliability.
- Listen for a rattle on cold start or under load — the main warning sign of chain stretch or tensioner wear.
Good question
Questions Okay gets asked a lot
How much does it cost to replace the timing chain on a BMW 3 Series?
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The BMW 3 Series uses a timing chain, which has no scheduled replacement interval. If a chain does wear or stretch and needs replacing, a UK independent garage typically charges £340–£968, as it is a labour-intensive job. There is no routine cambelt cost to budget for — just keep up with oil changes and act on any cold-start rattle.
Does the BMW 3 Series have a timing belt or a timing chain?
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Every modern BMW 3 Series uses a timing chain, not a rubber timing belt. This applies to petrol engines like the N20, N52, N55 and B48 and to diesels like the N47 and B47. Because it is a chain there is no fixed mileage replacement interval, but it is not maintenance-free. On some engines, notably the N47 diesel, the chain can stretch or fail and require replacement.
Why is the N47 diesel timing chain such a common problem?
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The N47 2.0 diesel, used in many 318d and 320d models from 2007 to 2014, has its timing chain mounted at the rear of the engine against the gearbox. BMW assumed it would last the life of the car, but chains can stretch and snap, often from around 60,000 miles on neglected cars. Because of its position the repair is labour-intensive, so regular oil changes and acting on any rattle are essential.
What happens if the timing belt snaps on a BMW 3 Series?
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Its belt-driven engines are interference designs, which means if the belt snaps the pistons strike the open valves. That causes bent valves and often piston and cylinder-head damage — a repair that frequently runs to four figures and can write off an older car. This is why replacing the belt on schedule, by age as well as mileage, is far cheaper than risking a failure.
Get a price for your BMW 3 Series
Estimate the timing belt cost for your exact engine and region, then compare quotes from trusted local garages.