BMW Timing Chain Failure


The N47 Timing Chain Problem
For some BMW owners, premature timing chain failure has become a serious problem - regularly discussed in BMW website forums, featured on BBC Watchdog and highlighted in other media sites.

The BMW diesel engine N47D20A (aka N47) produced during 2007, 2008 & 2009 appears to have a design problem affecting the timing chain. The timing chains are very weak and stretch over time, causing them to snap.

BMW timing chains have snapped on a range of models across the 1 Series, 3 Series and 5 Series.

The specific BMW models with engine code : N47 / N47D20A are detailed in the table below.

BMW Models Years
Engine Codes
118d 2007,2008,2009 N47 / N47D20A
120d 2007,2008,2009 N47 / N47D20A
123d 2007,2008,2009 N47 / N47D20A
318d 2007,2008,2009 N47 / N47D20A
320d 2007,2008,2009 N47 / N47D20A
520d 2007,2008,2009 N47 / N47D20A

The timing chain is located at the rear of the engine bay and is not intended to be a serviceable part, as described here by John Dabek, Principal of Forensic Engineering Associates.

IAAF e-Bulletin – BMW attempt to deflect blame for engine timing chain failure

What Happens When A Timing Chain Snaps?
When a BMW engine timing chain snaps, the inlet and exhaust valves collide with the pistons, resulting in massive engine damage. At this point it will bend all 16 valves, shatter the rocker arms, snap and distort both camshafts and the camshaft housing.

Rebuilding A Damaged BMW Engine
As you will imagine, repairing this catastrophic damage is a labour intensive and expensive job. The timing chain is located at the rear of the engine, therefore the engine rebuilder must remove the entire engine and completely strip down all components to replace damaged parts and restore the engine to running order. The N47 engine is rebuilt with modified chains, guides and tensioners supplied by BMW to reduce the risk of a repeat failure. The replacement parts required to rebuild the N47 engine are as expensive as you would expect from BMW.

If your timing chain has snapped then you will require a full rebuild which we can carry out for you at a cost of approximately £2,500 inclusive of parts.

Further Information on the Timing Chain Failure Issue
Earlier this year, our workshop specialist was consulted by researchers from
the BBC Watchdog programme – they were keen to acquire real-world professional
advice on this subject, and some of our engine rebuild customers had recommended
us as experts in this subject.

BBC Watchdog was producing a feature on the timing chain failure issue, having been
alerted by many unhappy BMW owners. Some of the BMW owners contacting Watchdog had been quoted huge repair costs from BMW and had instead chosen Prestige to rebuild their badly damaged engines. You can view their report here:

BBC Watchdog Report – BMW Timing Chain Failure – N47

Prestige Engine Rebuild & Repair Services
We are BMW diesel engine rebuild specialists and we became aware of the broken timing chain problem several years ago.

Combined with the ‘Swirl Flap failure’ problem, we have rebuilt over 160 engines in the last few years including the 118d, 120d, 123d, 318d, 320d, 520d.

I have personally been working on German cars for the past 25 years and I am a fully qualified Mercedes Benz trained technician and engine assembler.

At Prestige we have a well deserved reputation for technical excellence and superb customer care. We will collect your car from anywhere within mainland UK, rebuild the engine replacing all damaged parts and you will be able to enjoy driving it once again.

If you need any advice or help, please call Steve Baker at Prestige German Automotive on 07792 300252 to discuss your individual engine repair requirements and I will quote your engine repair work. Many thanks for taking the time to read.

Cheaper Engine Repair Solutions
If you are considering other companies offering so called ‘re-manufactured’ engines at under £2,000, our advice is please steer clear or do some thorough research. The chances are the engines are not rebuilt, nor re-manufactured, as genuine BMW replacement parts cost over £1,200.
It is more likely that the replacement engine will have been recovered from a damaged car – it’s also likely that it won’t have the modified BMW replacement timing chains, guides and tensioners – so they will just snap again…

It is a skilled and time consuming process to correctly repair an engine damaged by a broken timing chain, cheap solutions are unlikely to provide the reliability and warranty offered by Prestige.