The BMW N47 engine and its timing chain

If you like BMW engines (and you are a used-car market geek), the N47 will definitely ring a bell, and you have probably heard about its timing chain. In this article we land what is covered in the video (which you will find at the end of the article, if you prefer not to read as much), with the aim of understanding the problem, recognising symptoms and knowing what to check before you buy, especially if you are a professional buying for stock. In that case, go to our website (veiko.es) and take a look at our auctions.

What the BMW N47 engine is and why everyone talks about it

The BMW N47 is a four-cylinder diesel used very widely across several models from the brand. The conversation around the N47 is not usually “everything breaks”, but a very specific point: premature wear/stretch of the timing chain (on certain series and uses).

What does it mean that the chain “stretches”?

When people talk about a “stretched chain”, they usually describe progressive wear: the chain, guides or tensioners are not working as they should and metallic noises appear (clack-clack-clack). The real risk is leaving it: if the system eventually fails, the breakdown can be serious. 

Typical symptoms: the “clack-clack”

What workshop guides repeat most is:

• A metallic rattle on a cold start or at idle. Take a look at the source Star Garage Mansfield
• A noise that can get worse with mileage if nobody intervenes.

WATCH THIS: not every noise is the chain, but if the sound is there and consistent, the smart move is to diagnose as soon as possible.

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Are N47 engines bad?

The key, rather than demonising it, is to treat it as what it is: an engine that can need expensive preventive maintenance.

It is not a “doomed” engine by definition. There are units that have done many kilometres without drama, but there is a known pattern of chain problems in part of this family, often cited in the range of approx. 2007–2015.

Why is the repair usually expensive?

The video explains an essential idea: the N47 chain is at the back of the engine, which makes access harder and drives up labour hours.

In different technical guides and workshop cases it is mentioned that access can require major dismantling.

The result?
Although “changing a timing system” sounds standard, on the N47 it can become a job costing thousands (especially if you get there late, according to Taller Autotrac Vinaròs)

What to check if you are going to buy a BMW with an N47

If you buy for resale or for your fleet, this matters even more than for a private buyer, because your margin depends on buying well. Spotting a fault in time can save you a lot of money and also a lot of time (and that is very important to favour a fast stock turnover in your dealership)

1) Key questions (documentation and maintenance)

• Is there a maintenance history?
• Have oil intervals been shortened compared with the long “longlife” ones? (on sensitive engines, this can matter)
• Has the timing system already been done? If yes: invoice, parts replaced (chain/guides/tensioners) and mileage.

2) Signs on a test drive and diagnosis

• Cold start: listen carefully for the first few seconds.
• Idle: is there a persistent metallic rattle?
• If you have access to diagnosis/a prior inspection: any sign of abnormal noise is a clear indication that you should take it to a workshop.

3) When to negotiate vs. when to walk away

• Negotiate if the car fits but there is no clear proof the timing job has been done: your offer should include a possible preventive (or at least the risk).
• Walk away if the noise is obvious, the seller plays it down and there is no history: because the “cheap” car can become “expensive” very quickly.