Bavarian Motor Works was founded in 1916 and has become synonymous with automotive excellence. Known for the performance and durability of their engines, BMW has always been at the forefront of testing new frontiers of power output with improved fuel efficiency and reduced emissions.
BMW warranted their timing chains to last 105,000 miles on all their engines until they experienced a design error on their N20 and N26 engines during the 2012 to 2015 period. Timing chains failed prematurely after only 70,000 miles. BMW has been forced to accept liability for these failures.
The quest for creating the most desirable driving machines has always inspired engineers in Munich to push the envelope of engine design. Engines have become smaller, lighter, and more powerful while being more fuel-efficient and emitting less toxic emissions.
Let’s look at how the timing chain failures on the N20 and N26 engines reminded BMW of the price of pushing the limits too far.
The Great Reliability Of BMW Engines Marred
When challenged to find ways to make their engines lighter and more fuel-efficient, BMW engineers mostly remained convinced that a timing chain is stronger and more durable than the rubber timing belts used by some competitors.
The engineers made a compromise on the width of the timing belt, and they were made narrower and lighter in a quest to find the optimum strength and durability of the component. The timing belt guides and tensioner evolved along with the chain design to be lighter yet durable.
BMW was largely successful in the evolution of its engines and built up a repute for putting some of the best engines into the automotive industry. The specified replacement interval for timing chains on BMW engines was set at 100,000 miles, and many technicians observed that the timing chains were still in very good condition at this replacement cycle.
CarComplaints.com documents the more than 900 complaints lodged against BMW for various timing chain issues. The X3, X5, 325i, 328i, and 335i models reflect the highest number of recorded complaints, with the 2013 X3 singled out as the worst BMW in the stable. You can read about my own experience owning an X5 here (it was not good).
A class-action lawsuit in the US was finalized in December 2020 in favor of the owners of BMW models, which all experienced premature timing chain failure or catastrophic engine failure as a result of a defective timing chain.
Included in the BMW timing chain lawsuit are the following models:
- 2012-2015 BMW X1
- 2013-2015 BMW X3
- 2015 BMW Z4
- 2012-2015 BMW X4
- 2014-2015 BMW 228i Coupe, Convertible
- 2012-2015 BMW 320i
- 2012-2015 BMW 328i Sedan, Sports Wagon, Gran Turismo
- 2014-2015 BMW 428i Coupe, Convertible, Gran Coupe
- 2014-2015 BMW 428i xDrive
- 2014-2015 BMW 528i Sedan
- 2012-2015 BMW 428i xDrive
- 2012-2015 BMW 528i
All these models were powered by the N20 or N26 direct-injection turbocharged engines. These engines were prone to premature failure of the primary and secondary timing chain assemblies.
The role of the primary timing chain is to synchronize the camshaft and the crankshaft and to control the opening and the closing of the inlet and exhaust valves during the four-stroke combustion cycle.
Two modes of failure were observed. Firstly, the primary timing chain became stretched and loose, allowing the timing chain to skip some teeth on the timing sprocket, causing the synchronization between the camshaft and crankshaft to be out and resulting in the engine misfiring or running rough.
In severe cases, the timing chain misalignment resulted in the chain snapping and causing the engine to fail catastrophically. The pistons would collide with the valves and cause excessive damage to the engine.
Analysis of the failed components pointed to the primary timing chain becoming stretched and the tensioning rails and chain rails being made of brittle plastic that causes the timing chain tension to become too loose.
The secondary timing chain assembly consists of the crankshaft and counterbalance shaft sprockets, oil pump drive chain, pump drive sprocket, chain tensioner, and integrated guide and tensioner rails. This assembly appeared to operate as designed and showed no sign of failure.
What Has BMW Done To Correct The Timing Chain Failures?
BMW issued an extended 7-year/70,000-mile engine warranty for all timing chain-affected vehicles in 2017. BMW has agreed to honor all such extended warranties based on the lawsuit’s outcome in favor of the complainants.
Vehicles affected were recalled, and all timing chains were replaced at no later than 60,000 miles. BMW further agreed to compensate all affected owners who incurred repair and engine replacement costs based on an eight-year/100,000-mile ownership before the timing chain lawsuit settlement.
For all BMW models with less than seven years or 70,000 miles whose owners incurred costs for tow-in, diagnostics, and repairs that were performed before the 2017 warranty extension, BMW agreed to reimburse owners for 100% of the total invoice for work that was done by authorized BMW dealerships.
If independent repair centers performed the work, the vehicle owners were compensated for the labor up to $3,000 for the timing chain module and up to $7,500 for engine failure.
For BMW models that fall between the 7 years/70,000 mile extended warranty but less than the previous 8 years/100,000 miles warranty owners were compensated for work performed at authorized BMW dealers as follows:
- Up to 80,000 miles: BMW pays 75% / Customer pays 25%
- 80,001 to 90,000 miles: BMW pays 55% / Customer pays 45%
- 90,001 to 100,000 miles: BMW pays 40% / Customer pays 60%
- 100,001 miles and above: BMW pays 0% / Customer pays 100%
Compensation for work performed at independent repair workshops was paid a labor cap of $3,000, and the engine replacement costs were capped at $7,500 per vehicle.
The cost of the timing chain replacement will vary between independent repair workshops and authorized BMW dealers, but both options will be a lot less expensive than the inconvenience of a breakdown and a complete engine replacement.
Even great companies get it wrong sometimes, and their response to solving the problem says much about them. BMW has always sought to create excellent customer experiences, whether from the Sheer Driving Pleasure of their cars or their treatment of customers when things go wrong.
Conclusion
If you own a BMW built-in from 2012 to 2016, request an authorized BMW dealer to inspect the vehicle and perform the repairs mandated by the class action lawsuit. The timing chains on the BMW models fitted with the N20 and N26 engines need to be replaced every 60,000 miles to avoid the failure mode observed.
For all other BMW models not fitted with the N20 and N26 engines, you can maintain the planned timing chain replacement at the 100,000-mile mark. You may want to consider doing the timing chain replacement sooner than 100,000 miles to be on the safe side.
References
https://www.carwriteups.co.uk/2019/09/list-of-bmw-engines-that-are-notorious-for-breaking-down/