BMW B38 Engine

BMW B38 Engine Specs, Problems and Reliability

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By Scott Matthew

The BMW B38 engine series, with its 1.5-liter 3-cylinder design, has been in production since 2013 and finds applications in various vehicle configurations, including front-wheel drive (B38A15), rear-wheel drive (B38B15), and hybrid setups (B38K15). Additionally, these engines are utilized in Mini models, such as the 1.2-liter B38A12A and 1.5-liter B38A15A.

Specific Variants and Installations

  • B38A15U0 – 102 hp, 180 Nm:
    • Installed on BMW 2-Series F45 (2015–2018) and 2-Series F46 (2015–2018).
  • B38A15U1 – 109 hp, 190 Nm:
    • Installed on BMW 1-Series F40 (since 2020), BMW 2-Series F45 (2018–2021), and 2-Series F46 (since 2018).
  • B38A15M0 – 136 hp, 220 Nm:
    • Installed on BMW 2-Series F45 (2014–2018), 2-Series F46 (2015–2018), and BMW X1 F48 (2015–2017).
  • B38A15M1 – 140 hp, 220 Nm:
    • Installed on BMW 1-Series F40 (since 2019), BMW 2-Series F44 (since 2020), 2-Series F45 (2018–2021), 2-Series F46 (since 2018), BMW X1 F48 (since 2017), and BMW X2 F39 (since 2018).
  • B38B15U0 – 109 hp, 180 Nm:
    • Installed on BMW 1-Series F20 (2015–2019).
  • B38B15M0 – 136 hp, 220 Nm:
    • Installed on BMW 1-Series F20 (2015–2019), 2-Series F22 (2015–2021), and 3-Series F30 (2015–2018).
  • B38K15T0 – 231 hp, 320 Nm:
    • Installed on BMW i8 L12 (2013–2020) and i8 L15 (2017–2020).

These variants of the BMW B38 engine showcase a range of power outputs and torque specifications, enabling their integration into various BMW and Mini models across different production periods, catering to diverse performance and drivetrain needs.

Specifications

Production yearssince 2013
Displacement, cc1499
Fuel systemdirect injection
Power output, hp102 – 140
231 (hybrid version)
Torque output, Nm180 – 220
320 (hybrid version)
Cylinder blockaluminum R3
Block headaluminum 12v
Cylinder bore, mm82
Piston stroke, mm94.6
Compression ratio11.0
9.5 (hybrid version)
FeaturesValvetronic
Hydraulic liftersyes
Timing drivechain
Phase regulatorVanos
Turbochargingyes
Recommended engine oil0W-30, 0W-40, 5W-30, 5W-40
Engine oil capacity, liter4.25
Fuel typepetrol
Euro standardsEURO 6
Fuel consumption, L/100 km (for 318i F30)
— city
— highway
— combined
6.7
4.6
5.4
Engine lifespan, km~300 000

Exploring Common BMW B38 Engine Issues

The BMW B38 engine, despite its efficiency and performance, faces several recurring problems that owners should be aware of to ensure proper maintenance and preemptive care.

Vibrations and Noise on Idle

The B38’s inline-3 configuration leads to noticeable vibrations and increased noise levels during operation. Compared to more balanced engines like the inline-6 B58s, the inline-3 design lacks inherent smoothness due to fewer pistons. While this doesn’t signify engine malfunction, potential buyers should anticipate these characteristics before purchase.

Crankshaft Guide Bearing Failure

A critical issue with certain B38 engines involves premature wear of the crankshaft guide bearing. This malfunction can lead to clutch pedal dysfunction during gear shifts, accompanied by a check engine light and noise emanating from the transmission bell housing. While severe cases might cause engine damage, this occurrence is less common. The affected models primarily include F55 and F56 chassis Mini Cooper 4-door hardtop models produced between December 2014 and June 2015. It’s advisable to avoid vehicles from this specific production period or verify that the issue has been rectified through recalls or repairs.

Carbon Buildup

The implementation of direct injection technology in B38 engines leads to carbon buildup on intake ports. Direct injection, though efficient for fuel economy, causes carbon deposits on valves, hindering their optimal operation. Over time, this buildup can result in engine misfires and trigger the check engine light. Periodic walnut blasting, around every 60,000 miles, is recommended to remove these carbon deposits and maintain proper valve functionality.

Coolant Leaks From Turbo

Coolant leaks are a prevalent issue in B38 engines, particularly from the turbo due to O-ring failures in the coolant lines connected to the turbo. While these leaks are minor, they can manifest as greenish contaminants around the turbo area. Identifying such leaks and promptly replacing the O-rings while replenishing the coolant levels is crucial to prevent potential overheating and engine damage.

Water Pump & Thermostat Failures

Though less frequent in B38 engines compared to older BMW models, water pump and thermostat failures still occur over time, typically after around 5 years. These failures often result in leaks and overheating, potentially leading to severe engine damage. Addressing bluish coolant leaks and high temperatures promptly is advisable to prevent long-term complications.

VANOS Failure

The BMW variable valve timing system (VANOS) regulated by VANOS solenoids can malfunction, triggering the check engine light or causing the vehicle to enter limp mode. VANOS issues might indicate solenoid-related problems, necessitating diagnostic checks and potential replacements.

Awareness of these common issues and proactive maintenance measures, including periodic inspections and timely repairs, is essential to preserve the longevity and performance of BMW B38 engines.

Conclusion

The B38 gasoline engines made their initial appearance in the i8 coupe hybrid power plant but later expanded to conventional models. Key design features include an aluminum block with plasma-sprayed steel and a closed jacket, a 12-valve aluminum cylinder head with hydraulic lifters and direct fuel injection, Vanos phase shifters on both camshafts, Valvetronic system, and a timing chain drive. The engine is supercharged by a single water-cooled Continental turbocharger, complemented by a balancing shaft and a Bosch MEVD 17.2.3 control unit.

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