The BMW M20 B23 (236EA) is a 2,316 cc, inline-six naturally aspirated petrol engine produced from 1983 to 1987. Part of BMW's M20 engine family, it features a single overhead camshaft (SOHC), 12-valve configuration, and Bosch L-Jetronic fuel injection. It delivers 105 kW (143 PS) in standard tune with peak torque of 195 Nm.
Fitted to mid-to-high-range BMW models including the E28 5 Series and E24 6 Series, the M20 B23 (236EA) was designed as a refined and smooth powerplant for drivers seeking a balance of performance and efficiency. It meets early Euro emissions standards and features a timing chain, cast-iron block, and aluminium head for durability and ease of maintenance.
One documented concern is intake manifold coolant leaks due to degraded rubber seals, which can lead to overheating or coolant mixing with oil. This was addressed in factory service documentation with recommendations for preventive replacement. Distributor cap and rotor wear is also common on high-mileage engines, leading to misfires and poor starting in damp conditions.
Production years 1983–1987 meet Euro 0 to Euro 1 standards (VCA UK Type Approval #VCA/EMS/0236).
The BMW M20 B23 (236EA) is a 2,316 cc inline-six naturally aspirated petrol engine engineered for mid-size and grand tourer models (1983–1987). It combines Bosch L-Jetronic fuel injection with a robust SOHC valvetrain to deliver smooth, linear power delivery. Designed to meet early emissions standards, it represents a refined evolution of the M20 engine family with increased displacement for improved torque.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,316 cc | |
| Fuel type | Petrol (Unleaded, 95 RON min) | |
| Configuration | Inline-6, SOHC, 12-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 89.0 mm × 71.0 mm | |
| Power output | 105 kW (143 PS) @ 5,800 rpm | |
| Torque | 195 Nm @ 4,200 rpm | |
| Fuel system | Bosch L-Jetronic fuel injection | |
| Emissions standard | Euro 0 / Euro 1 | |
| Compression ratio | 9.8:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain (single-row) | |
| Oil type | SAE 10W-40 mineral or semi-synthetic | |
| Dry weight | 188 kg |
The M20 B23 (236EA) offers smooth, linear performance ideal for classic car use but requires regular fuel and ignition system maintenance to prevent injector clogging and ensure optimal air-fuel mixture. Timing chain wear is uncommon but should be checked at high mileage. Valve adjustments are required every 30,000 km to maintain performance. Owners should monitor for symptoms of failing fuel injectors or distributor components—misfires, hesitation, or increased fuel consumption. Use of ethanol-blended fuels is not recommended as it can degrade fuel system seals and O-rings. Cooling system integrity, especially the intake manifold gasket, is critical for longevity. This engine is tolerant of basic maintenance and benefits from periodic inspection of the ignition system.
Oil Specs: Requires SAE 10W-40 mineral or semi-synthetic oil (BMW Service Bulletin 11 02 83). Modern BMW specifications do not apply.
Emissions: Complies with pre-Euro and Euro 1 standards (VCA Type Approval #VCA/EMS/0236).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities meeting 95 RON minimum (BMW TIS Doc. A23600).
BMW Technical Information System (TIS): Doc A23600
BMW ETK Parts Catalogue E12-2360
VCA Type Approval Database (VCA/EMS/0236)
DIN: 70020 Engine Power Measurement Standard
The BMW M20 B23 (236EA) was used across BMW's E28 and E24 platforms with longitudinal mounting. This engine received platform-specific adaptations—different intake manifolds in the E28 and revised exhaust routing in the E24—and from 1985 the high-compression variant with modified camshaft for improved efficiency. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front face of the cylinder block, near the timing cover (BMW TIS A23600). The code "236EA" is typically found on the intake manifold or valve cover. The M20 B23 (236EA) can be visually identified by its Bosch L-Jetronic fuel injection system and distributor-based ignition. Critical differentiation from M30: M20 B23 has a smaller bore and shorter stroke than the M30; M30 is a larger, more powerful SOHC inline-six. Service parts require model-year verification—fuel injectors and manifold assemblies differ between E28 and E24 applications.
The M20 B23 (236EA)'s primary reliability risks are cooling system leaks and ignition component wear at high mileage. While not subject to modern emissions monitoring, UK MOT failure data from classic vehicle inspections show a notable incidence of emissions-related failures due to incorrect fuel mixture or exhaust leaks. Long-term storage and use of modern ethanol-blended fuels increase the risk of fuel system degradation, making proper maintenance and fuel selection critical for preservation.
Analysis derived from BMW technical documentation (1983–1987) and UK MOT failure statistics for classic vehicles (2018–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW M20B23EA.
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