BMW’s turbocharged four-cylinder engines from the mid-2010s have earned a reputation for being unreliable, primarily due to several issues, the most notorious being brittle plastic timing chain guides that can lead to engine failure.
In a recent teardown video by the I Do Cars YouTube channel, they explored a failed N26 four-cylinder engine, shedding light on the reasons behind these widespread failures. A significant factor in this reliability issue appears to be BMW’s recommendation of a 15,000-mile oil change interval. This extended interval may allow varnish and sludge to accumulate in the engine, leading to the degradation of plastic and rubber components over time.
The condition of this particular engine certainly aligns with that theory, as evident from the dark brown-stained metal in the head. As Eric, the host of the video, delves deeper into the engine, he discovers multiple chunks of the original plastic timing chain guide. His investigation leads him to the oil pickup tube, which was completely obstructed by debris from the timing chain guide.
The accumulation of these chunks was significant enough to block the oil flow to the pump, ultimately starving the engine of critical oil and resulting in considerable wear and damage. On a positive note, many of the internal components were still salvageable, offering a glimmer of hope amid the bad news.
In response to these issues, BMW has adjusted its oil change recommendations to every 10,000 miles—an improvement over the previous guideline, but still not as frequent as the 5,000 to 7,000 miles that many experts suggest. This teardown serves as a crucial reminder that prioritizing regular oil changes is essential; neglecting this can lead to costly repairs in the future.
