Mini Cooper S N14 Engine Teardown Reveals What's Wrong With BMW's Design

Aug. 19, 2023 3:11 PM ET byRoy Robles Video /6 Comments

The N14 engine was co-developed by PSA and BMW.

迷你库柏年代one of the most influential carsyou can buy today. But if Eric, otherwise known as I Do Cars on YouTube, is to be believed, some older models have some of the worst track records regarding engine reliability.

In the video below, Eric tore down an engine from a 2010 Mini Cooper - the N14B16A 'Prince' engine co-developed by PSA (now Stellantis) and BMW - and discovered why he wouldn't be keeping one soon.

This 1.6-liter, four-cylinder, turbochargedMini Cooperengine has an aluminum block and head, making 172 hp and 150 lb-ft of torque. It wasn't bad for the time, but these engines are known for specific problems, including timing guide failures, high-pressure fuel pump issues, and carbon buildup due to limited port injection. Forums are filled with horror stories about the issues these engines faced, especially in Minis.

Curiously, many of these issues never plagued French brands under the PSA banner, as Peugeot continued development of the motor and eventually turned it into a reliable, fun motor. Mini? Not so much.

The teardown was off to agreatstart. As Eric drained the oil pan, instead of just oil coming out of the plug, it was clear water and a little oil for good measure. Another stumbling block was the oil filter being located at a very inconvenient location under the engine harness. He surmised that he wouldn't be surprised if many users didn't get to change the oil filter just because of that.

Removing the stock BorgWarner K03 turbocharger revealed it to be in decent condition, but its impellers were immobilized, rendering it ineffective for the forced induction system. A thorough examination showed the valves and camshafts coated in a grimy substance, likely due to a water-oil mixture, culminating in seizure. This situation parallels a prior video of disassemblingan aged Ecoboost engine, though the current scenario appeared notably worse.

After sifting through the gunk and grime and even a broken exhaust valve, he came across a piece of the plastic timing guide floating around the engine wall. It could have probably been replaced before, but the debris wasn't taken out completely, causing the fuel and oil pump to pump in water, causing the corrosion inexplicably, and what he can only describe as a "blow-out."

Though this teardown raises doubts about these engines' reliability, proper upkeep can extend their lifespan. If it works, it's a fun engine, especially with the Mini Cooper S. While some have achieved hundreds of thousands of miles with routine oil changes, the engine in the video might be near its end.

Thankfully, newer Minis switched to BMW engines which have proven more reliable, and with the next-gen Mini Hardtop going electric-only in two-door guise, it won't face these problems at all.