BMW i8 I12

Modular three-cylinder turbo with a lively character. Turbocharger and timing chain are wear items; vibration balance handled by a balancer shaft.

• !! Timing chain elongation from 70,000 km

  Same timing chain issue as N20 and B48. Plastic guide rails wear out, chain elongates. Slightly less loaded on the 3-cylinder.

  Symptoms: Rattling on cold start, engine check light, rough idle
  1,500–3,500 $
  Ad BMW B38 timing chainBMW B38 chain tensioner
• !! Crankshaft bearing half-shell undersized (early production) from 80,000 km

  Early B38 engines (manual gearbox, built before April 2015) had an undersized crankshaft half-shell bearing. BMW switched to 360° bearings and replaced affected engines as a goodwill gesture (up to 120,000 km / 5 years).

  Symptoms: Knocking or hammering from the engine block under load; oil pressure drop; in extreme cases engine seizure due to spun bearing
  3,000–8,000 $
  Ad BMW B38 crankshaftnlagerBMW B38 Lagerschale
• !! Turbocharger shaft seal leaking — oil consumption from 100,000 km

  Turbocharger shaft seals become porous and allow oil into the combustion process. On the 3-cylinder, exhaust gas pressure pulses cause higher wear than on four-cylinders.

  Symptoms: Blue smoke on cold start or wide-open throttle, oil consumption above 0.5 L/1,000 km, oil mist in intercooler, smoke after long motorway run.
  600–2,000 $
  Ad turbocharger B38B15 F20Turbo Welle gasket BMW 118i B3811657648513

+ 4 more engine weaknesses + vehicle weaknesses