Plastic timing chain guides and extended oil change intervals cause some turbocharged BMW engines to risk oil starvation
BMW’s turbocharged four-cylinder engines from the mid-2010s have earned a reputation for being unreliable, largely due to various issues, with the most significant being brittle plastic timing chain guides, which led to the failure of this particular engine.
In a teardown video by the I Do Cars YouTube channel, they examine a failed N26 four-cylinder engine, offering a closer look at why so many of these engines experience breakdowns. The prevailing theory blames BMW’s recommended 15,000-mile oil change intervals, which can cause varnish and sludge to accumulate, damaging both the plastics and rubber components.
This engine seems to confirm that theory, with dark brown-stained metal in the cylinder head as evidence. As Eric, the video’s host, continues the teardown, he discovers fragments of the plastic timing chain guide scattered throughout the engine. The investigation reaches its peak when he finds the oil pickup tube completely clogged with pieces of the broken timing chain guide.
The chunks were abundant enough to block the oil flow to the pump, starving the engine of essential lubrication and leading to significant wear and damage. Surprisingly, many internal components were still salvageable, so it’s not all bad news.
Today, BMW advises oil changes every 10,000 miles—an improvement from earlier recommendations, but still not as frequent as the 5,000 to 7,000-mile interval that’s likely safer. As this teardown shows, prioritizing regular oil changes is crucial, or you’ll end up paying for it later.
