The BMW M52 B20 (206S4) is a 1,991 cc, inline-six naturally aspirated petrol engine produced between 1994 and 1998. It features DOHC, 24-valve configuration, and individual throttle bodies, delivering 110 kW (150 PS) and 190 Nm of torque. Its high-revving nature and smooth power delivery provide an engaging driving experience typical of BMW's inline-six heritage.
Fitted primarily to the E36 3 Series (320i), the M52 B20 was engineered for balanced performance and everyday usability. It met Euro 2 emissions standards using Bosch Motronic M5.2 engine management and a three-way catalytic converter. The engine's design emphasizes responsiveness and refinement in urban and highway driving conditions.
One documented concern is premature cylinder head cracking, particularly on early builds, due to the use of aluminium-silicon alloy with insufficient reinforcement around the coolant passages. This issue was addressed in later revisions with improved casting techniques and revised cooling system design per BMW Service Information Bulletin 11 03 97.
Production years 1994–1998 meet Euro 2 standards (VCA UK Type Approval #VCA/EMS/5678).
The BMW M52 B20 (206S4) is a 1,991 cc inline-six naturally aspirated petrol engine engineered for compact executive models (1994–1998). It combines individual throttle bodies with dual overhead camshafts to deliver high-RPM responsiveness and smooth power delivery. Designed to meet Euro 2 standards, it balances driver engagement with daily drivability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,991 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 80.0 mm × 66.0 mm | |
| Power output | 110 kW (150 PS) @ 5,900 rpm | |
| Torque | 190 Nm @ 4,200 rpm | |
| Fuel system | Bosch Motronic M5.2 sequential port fuel injection | |
| Emissions standard | Euro 2 | |
| Compression ratio | 10.8:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven (double-row timing chain) | |
| Oil type | BMW Longlife-98 (SAE 10W-40) | |
| Dry weight | 165 kg |
The high-revving inline-six provides crisp throttle response and smooth power delivery, ideal for spirited driving, but requires adherence to 15,000 km oil change intervals to maintain camshaft and chain longevity. BMW Longlife-98 (10W-40) oil is critical due to its thermal stability and protection under high-RPM operation. Premature cylinder head cracking can occur if cooling system maintenance is neglected; regular coolant replacement and thermostat inspection are essential. The Motronic M5.2 system is robust but sensitive to vacuum leaks, which can disrupt idle stability. Later models (post-1996) feature revised head castings; pre-1996 units should be inspected for micro-cracks per BMW SIB 11 03 97.
Oil Specs: Requires BMW Longlife-98 (10W-40) specification (BMW SIB 11 03 97). Supersedes ACEA A2/B2 requirements.
Emissions: Euro 2 certification applies to all production years (1994–1998) (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities meeting EN 228.
BMW Technical Information System (TIS): Docs A23570, A23612, A23701, SIB 11 03 97
VCA Type Approval Database (VCA/EMS/5678)
DIN Deutsches Institut für Normung: DIN 70020 Engine Power Measurement
The BMW M52 B20 (206S4) was used across BMW's E36 platform with longitudinal mounting. This engine received platform-specific adaptations-integrated VANOS on later units-and from 1998 the facelifted E36 LCI adopted the M52TU variant with revised intake and updated engine management, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the right-side engine block near the exhaust manifold (BMW TIS A23890). The 7th VIN digit indicates engine family ('M' for M52 series). Pre-1996 models have silver valve covers with "M52" branding; post-1996 units include "VANOS" on the cover. Critical differentiation from M52TU: Original M52 B20 lacks secondary air injection and uses Motronic M5.2 ECU, while M52TU features secondary air pump and MS41.1 ECU. Service parts require production date verification - cylinder heads before 09/1996 are prone to cracking and should be replaced with post-revision units per BMW SIB 11 03 97.
The M52 B20's primary reliability risk is cylinder head cracking on early builds, with elevated incidence in high-temperature operation. Internal BMW reports from 1997 indicated a significant number of pre-1996 units requiring head replacement before 150,000 km, while UK DVSA records show coolant-related failures were common in neglected examples. Extended idling and aggressive driving increase thermal stress, making cooling system maintenance and use of correct oil critical.
Analysis derived from BMW technical bulletins (1995–1999) and UK DVSA failure statistics (1998–2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW M52B20-206S4.
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