BMW 320d Timing Chain Rattle: What It Means and What to Do

The engine behind the problem

Between roughly 2007 and 2014, BMW fitted its N47 2.0-litre diesel to most of its four-cylinder diesel cars: the 116d, 118d, 120d, 318d, 320d, 520d, X1 and X3. It is a smooth, economical engine, and plenty of them are still on the road around Birmingham. It is also the engine behind one of the best-known BMW faults — the timing chain.

What goes wrong

A timing chain is meant to last the life of the engine. On the N47, the chain and its plastic guides can wear prematurely. As they wear, the chain stretches and starts to rattle. If nothing is done, it can eventually jump teeth or snap, and because the N47 is an interference engine, that usually means the valves hit the pistons and the engine is destroyed.

BMW placed the chain at the back of the engine, next to the gearbox. That makes it quiet and compact, but it also means repairing it is a big job — the engine or gearbox has to come out.

How to recognise the rattle

The classic sign is a rattling or whirring noise from the rear of the engine, closest to the windscreen. It is often most noticeable at idle, when the engine is warm, or when you lift off the accelerator. Open the bonnet with the engine idling and listen at the back. Other noises — a worn auxiliary belt tensioner or a failing pulley — can sound similar, which is why a proper diagnosis matters.

Why you should not wait

There is no reliable way to know how long a rattling chain will last. Some go on for months; some fail within weeks. A chain replacement is a significant cost, but it is a fraction of a replacement engine. If your 320d or 120d has started to rattle, it is worth getting it checked straight away and avoiding long journeys until you know what you are dealing with.

What the repair involves

A proper repair replaces the timing chains, guides, tensioner and seals together. With the engine out, it also makes sense to look at the clutch and dual-mass flywheel on manual cars, as replacing them at the same time saves a lot of labour if they are worn. We then refill with the correct BMW-approved oil.

Can you prevent it?

Nothing guarantees a chain will last, but regular oil changes with the correct oil are widely thought to help. BMW's long-life service intervals can mean two years between oil changes on a low-mileage car, and we generally suggest changing it at least every year or 10,000 miles on an N47.

If you are unsure whether your BMW has the N47, or you think you can hear a rattle, call us on 0121 476 2287 or book a check online.

Buying a used N47 BMW

If you are looking at a 2007–2014 BMW diesel, ask whether the timing chain has been replaced and ask to see the invoice if it has. A car with the work already done is worth more than one without. Listen to the engine from cold and again when it is warm, and walk away from any car with a rattle that the seller cannot explain.

Look at how often the oil has been changed. A car that has had its oil changed every year is a safer bet than one that has run the maximum long-life interval every time. If you want a second opinion, we can listen to a car and look over its history before you buy.