The AA Blog: BMW N47 Chain Problem Myth – The Truth

Categories:BMW, Bmw f10, BMW f11, N47 engine

The biggest BMW myth of them all

The N47 engine AND the b47 engine, does it ring a bell? If you’re one that doesn’t know what the N47 engine and the b47 is, continue reading..

The truth about the N47 engine

Find out what the N47 engine is really like, does it really have a weak chain? or is it something else? Find out…

The N47 engine

The N47 engine is an diesel engine from BMW, you’ll find these engines in the 1 series, 3 series and 5 series as a 1.6 and a 2.0 litre engine.

The B47 engine

The B47 engine was the replacement engine for the N47 which was debuted in 2014. This engine also came with a lot of talk about it having a weak chain not long after.

About the N47 – First use

The N47 engine debuted in March 2007 in the facelifted 1 Series BMW E87 and E81 and was available in the 1 Series BMW E82 and E88, which were introduced later in the same year.

The engine is a four-cylinder common rail diesel engine that has many improvements over its predecessor, the M47. But in 2014 it was replaced with the B47 engine.

If you’ve just bought a car with the N47 engine, don’t instantly be put off! Or are you looking at a car that has the N47 engine and you’re here doing some research? What I will say to you is, check the service history of the car, check for oil servicing!

Also, listen out, see if you can hear a rattling noise from the rear of the engine. (View the car on a cold morning, and listen out for the rattling noise.)

Timing chain issues

The N47 engine family (N47D16, N47D20) is prone to excessive timing chain wear and premature failure. But is the problem with the timing chain or is the problem with BMW recommended service intervals and driving styles?

With many BMW cars being leased out for sales specialists for such big companies, many of these cars were not serviced on time with cars reported doing over 20K before a service.

This raises the question as to whether there are any external factors which contribute to the premature failure of the chains, such as more frequent oil/filter changes?

For those that know of this problem have you ever noticed that these “chain snaps” in cars have different millages when you searched?

Some cars reported having 26K miles, 52k miles, 100k miles, and others over 150k miles. This shows that the millage does not matter, Its down to the driving style. 98% of chains snap on engine start, what does it mean?

It means that the starting of the engine is the biggest effort for a timing chain, for a chain to snap while driving on the motorway is almost rare!

BMW’s are often driven hard, Why? Well because it’s a BMW and owners of them think it’s okay to do so without any thought or sympathy.

What does a Oil expert says?

An oil expert has said that there hasn’t been a single report of a N47 timing chain snap if you drive sensibly and change your oil before 10,000k miles, this is a complete myth, which has been fueled by BBC Watchdog. The problems have occurred due to two primary factors. The long ‘official’ BMW service intervals and driving style.

These service intervals were brought in to keep the fleet market happy, who get rid of cars at 3-4 years old and 60k miles. If only 1 or 2 oil changes in that time, then maintenance costs are greatly reduced.

However, oil that has done 15-18k miles has suffered a horrible amount of degradation, and its lubricating properties are pretty much shot. Fast forward 4 or 5 years and those timing chains end up getting stretched, jump a link, and the engine is goosed. Also, people not cooling the turbo (especially in diesels).

“After a long run at speed, you pull into the service station and switch off the engine immediately. The oil that is around the bearings of the turbocharger stops moving and sits there.

The turbo is at a high temperature, and that oil basically gets cooked. Some of it turns to solid carbon. Eventually, those lumps of carbon dislodge and move around the engine. You HOPE that they end up in the sump. However, they’ll also tend to get stuck in any really small pipe/nozzle – like the ones that spray the oil onto the timing chain to keep it lubricated, for example. Those block up, no oil on the timing chain, engine goosed again. I’ve never seen an N47 engine fail with excellent service history.”

I recommend those people that have a BMW with the N47 engine to service it every 7,000 miles, chains need fresh oil to stay healthy, and so do turbos.

Lease companies hire cars out on maintaince free contracts of normally 3 years 36k miles, you get the car serviced every year and hand it back at the end of the period with the mileage at no more than 36k or you pay a fee for every mile you go over.

Unscrupulous individuals or companies do as many miles as they like and just clock the vehicle prior to the hand back with a fully stamped service book. Invariably joe blogs buys what he thinks is a low mileage car with provenance but in reality, it’s far from it.

How much is a n47 chain replacement?

If you have a n47 in your 1,3 or 5 series bmw and assuming it isn’t an x-drive, the cost to replace the n47 chain with the following:

The total cost is around £1,399 inc VAT.

High mileage N47

If you look after your n47 engine, and just like any other engine, it will keep on going. So to end this, if you change the engine oil and air, oil and fuel filters with good oem products, you have nothing to worry about and your n47 engine will achieve 750,000 miles and above.

Drive your BMW more carefully, it’s not a race. Have some “mechanical sympathy” understand how the car works and it will make you a better driver.

b47 engine and the n20 engine

The b47 and the n20 engine by BMW was meant to be the better of the 2.0.

BMW said the b47 engine had improved from the previous n47 platform.

The n20 engine which replaced the n53 engine in 2011 hasn’t had much improvement.

The b47 engine was released in 2014 and was also a 2.0 engine. Sadly not long after 2015 this engine had a lot of talk about it having the same “weak chain” as the n47 engine.

This is completely rubbish.

We have to understand that BMW’s don’t get driven around like any other car, BMW’s get driven around like its a race, with many owners remapping engines to go even faster..

If you want a fast BMW don’t buy a 2.0 n47, b47 or a n20, get yourself an BMW M5.