BMW N47 diesel common problems

Common problems and what to look for on the N47

The known issues most worth checking when you view a car with this engine. None of them means a car is a bad buy, but they're worth knowing about before you buy, and a good history often shows they've been dealt with.

1. Timing chain wear at the gearbox end

   What to look for: Ask for the engine to be started from cold, ideally after standing overnight, with the bonnet open. Listen at the back of the engine, near the bulkhead, not just at the front. The normal diesel clatter is even and comes from the top of the engine. A metallic rattle, whine or ticking from the back, on start-up or as the revs fall after a blip, is the thing to note. Ask for any invoice for timing chain work, and for the oil change record.

   Why it matters: The N47 has its timing chain at the rear of the engine, so replacing it is an engine-out job. The chain can stretch and the tensioner can fail to take up the slack, and in the worst cases the chain breaks and the engine is badly damaged. Engines built from March 2007 to early 2009 were the most affected, and BMW ran a workshop campaign for some of them in some markets. Revised parts followed in 2009, 2011 and from 2013 to 2015, which reduced the risk, though wear has been seen on later engines too, mostly where servicing was infrequent. Many specialists replace the chain, guides and the oil pump chain at around 100,000 miles. Many cars have had it done by now, and a car with that invoice is in a good position.

2. EGR cooler recall

   What to look for: Ask a BMW dealer to check the car by its VIN (on the V5C) and confirm that all EGR cooler recall work has been done. On the drive, note any loss of power, a burning smell, or a low coolant warning.

   Why it matters: The cooler in the exhaust gas recirculation system can leak coolant internally, and in rare cases the residue mixed with soot can catch fire. BMW recalled 268,000 UK diesels in 2018 and extended the recall in 2019, covering N47 models built from 2010 and 2011 on, such as the X3 from August 2010, the 5 Series from March 2011, the 1 Series from November 2011 and the 3 Series from December 2011. Later campaigns brought an improved cooler, so a car fixed once may need the newer part. It is a free fix at a dealer.

3. Sooted EGR valve and swirl flaps

   What to look for: On the drive, note any flat spots, hesitation or a lack of pull, and whether the engine management light is on. Ask whether the EGR valve or inlet manifold has been cleaned or replaced.

   Why it matters: Soot from the exhaust gas recirculation system builds up in the EGR valve and the swirl flaps in the inlet manifold, which costs performance and can bring on the engine management light. Cars used mainly on short trips build up soot fastest. Cleaning or replacing the parts restores the running.