First of all, what is a timing chain?
A timing chain is a very important internal part of an engine. It keeps the valves in perfect sync so they open and close at the right time. Modern BMW engines are known as “interference engines” which means that if the timing of the engine were not kept perfectly by the timing chain, pistons could collide with the valves and cause severe engine damage.
Ok, do I have an N47 engine in my BMW?
The BMW N47 engine was found in the 1 series, 3 series and 5 series including the E87 LCI and E81, E82 and E88, E9X LCI, E60/E61 LCI and F10/F11 models.
Production of the N47 common rail diesel engine began in 2007. In mid-2009, modifications were made to the chain design which did reduce the likelihood of failure but did not eliminate it. The main problems with the N47 timing chain were noted until 2011 although there are still, albeit fewer, reported problems after this.
In 2014, BMW replaced the N47 engine with the B47 which uses same chain design but left the poor reputation of the N47 behind.
Do I need to replace my N47 timing chain?
BMW engines have for a long time used a timing chain rather than a cam belt design. This is largely to give the owner confidence that it is a “lifetime” part and therefore a non-serviceable item, reducing costs as a result. The N47 had the timing chain placed at the rear of the engine as BMW felt that access to it would not be needed for the life of the vehicle. BMW usually consider lifetime to mean 100,000 miles.
Replacement of the timing chain on the 1 series, 3 series and 5 series engines normally require removal of the engine. Depending on the RPM at the time of failure, the engine may or may not be salvageable due to the high possibility of internal engine damage.
It is important to have your vehicle inspected if you notice any symptoms of the timing chain failing, as if you have the chain replaced before it has snapped you are less likely to suffer catastrophic damage to internal engine components.
Common signs your N47 timing chain may be failing
Tell-tale signs of problems with your timing chain will be a rattling or even metallic sounding noise from the rear of the engine nearest the windscreen.
Due to the extra stress on the timing chain when cranking, it is unsurprisingly common that so many BMW N47 owners report non-start issues after stopping briefly to refuel for example. If the engine is immediately turned off and not allowed to cool, the oil deposits within the engine are unlikely to return to the sump and will likely turn to carbon within the engine itself.
Can I prevent N47 timing chain failure?
Regular servicing is important with any engine but even more important with BMW N47 engines. It is recommended to service these engines around every 5,000 miles as old oil does not lubricate as well and high temperature oil turns to carbon.
These lumps of carbon move around the engine and can block nozzles which would be keeping the timing chain lubricated and running smoothly. It is also important to know the signs of timing chain failure, such as the distinctive noise you will hear so you can get your BMW repaired sooner rather than later.
If you have the option of automatic stop-start on your BMW, it is advisable to turn this off or have this option coded out to avoid additional stress on your timing chain and components.
If you are at all unsure and you have a noise you think may be your timing chain, drop it in to Absolute BM in Worcester where we will be more than happy to have a listen and advise you on the best way forward for you and your BMW.
My N47 timing chain has failed, what are my options?
Unfortunately, many owners end up needing a replacement engine. When the engine has been running out of time, the valves open and close at the wrong time so pistons can become damaged, along with valve lifters, rockers and camshafts.
It is often more cost effective to replace with a reconditioned engine from £3500 rather than costly strip down and diagnose only to find the engine has suffered catastrophic damage and is uneconomical to repair. As a BMW Specialist, we are also a supplier of brand new BMW engines at a very competitive price.
A second-hand engine is a possibility but there is no guarantee damage has not already been done and no warranty would be available should this replacement engine fail in the future.
If you have any concerns about your timing chain, it is best to get this checked as soon as possible to keep costs down. At Absolute BM in Worcester, we are more than happy to advise you on what your BMW may need and find a solution to suit your budget.