BMW 320d Timing Chain Rattle: Is Your N47 Engine at Risk?

Which BMWs have the N47 engine?

The N47 is the 2.0 litre four-cylinder diesel BMW used from 2007 until it was replaced by the B47 around 2014 and 2015. It powers a huge number of cars: the 116d, 118d and 120d, the 316d, 318d and 320d, the 520d, and the X1 and X3 20d among them.

It is a strong, economical engine with plenty of performance. Its weak point is the timing chain.

What goes wrong

The timing chain on the N47 runs on plastic guides, and it is at the back of the engine next to the gearbox rather than at the front. Over time the guides wear and the chain stretches. Long gaps between oil changes speed that up.

As the chain loosens, it starts to rattle or whine. If it is left, the chain can jump teeth or snap. On a diesel engine that usually means the pistons hit the valves, and the engine is often not worth repairing afterwards.

What the rattle sounds like

The typical N47 chain noise is a metallic rattle or a whine from the back of the engine, closest to the windscreen. It is usually easiest to hear at idle when the engine is warm, with the bonnet open or the windows down. It often gets gradually louder over weeks or months.

Other things can make similar noises, including a worn dual-mass flywheel, a loose heat shield or injector noise. That is why it is worth having it listened to by someone who knows these engines, rather than assuming the worst or the best.

Why the repair is a big job

Because the chain is at the back of the engine, replacing it means removing the engine or the gearbox for access. It is a substantial job, but it is still far cheaper than a replacement engine.

When we do it, we replace the chains, guides, tensioner and sprockets as a complete kit so the job only needs doing once. With everything apart, it is also the right time to check the clutch, flywheel and rear main oil seal.

Protecting your N47

Regular oil changes with the correct BMW-approved oil are the best protection. Many cars ran long variable service intervals when new, and those that did are more likely to have chain wear now. If you are buying a used N47-engined BMW, ask whether the chain has been done and listen carefully on a warm idle.

Signs the chain has already slipped

Sometimes the chain has already moved before the owner notices a rattle. Warning signs include the engine management light, a car that is harder to start, rough running or a sudden loss of power. Fault codes relating to camshaft and crankshaft position correlation can also point to a stretched chain.

If any of these appear alongside a rattle, stop driving the car and have it checked. Driving on with a chain that has jumped can cause the valves and pistons to meet, and at that point the cost rises sharply. A quick diagnosis now is far cheaper than a replacement engine later.

Getting it checked in Oldbury

If your 320d, 120d or 520d has started rattling, do not wait for it to get louder. Call us on 0121 544 3736 to book a check at our Oldbury workshop and we will tell you exactly what the noise is.