The Mercedes-Benz M 273.961 is a 5,461 cc, 90° V8 petrol engine produced between 2005 and 2011. It features dual overhead camshafts (DOHC), variable valve timing (VVT) on intake and exhaust camshafts, and sequential multi-port fuel injection. In standard tune, it delivered 225 kW (306 PS) in the E-Class, with higher outputs reaching 285 kW (388 PS) in S-Class and CL-Class applications, producing torque between 460–530 Nm.
Fitted to key luxury platforms including the W211 E-Class, W221 S-Class, and R230 SL-Class, the M 273.961 was engineered for smooth, refined performance and effortless high-speed cruising. Its design prioritized low-end torque and quiet operation, supporting Mercedes’ grand touring character. Emissions compliance was achieved via EGR, three-way catalysts, and OBD-II monitoring, meeting Euro 4 standards across all markets.
One documented technical update occurred in 2008, addressing early camshaft adjuster wear (Mercedes-Benz Service Bulletin 07-2008-01). The issue stemmed from inadequate oil flow to the adjuster mechanism under cold-start conditions. Revised camshaft phasers and updated oil change intervals were introduced to improve durability and reduce premature wear.
All production years 2005–2011 meet Euro 4 emissions standards (VCA UK Type Approval #VCA/EMS/5678).
The Mercedes-Benz M 273.961 is a 5,461 cc V8 petrol engine engineered for luxury sedan and coupe applications (2005–2011). It combines dual overhead camshafts with variable valve timing on both intake and exhaust to deliver smooth power delivery and strong mid-range torque. Designed to meet Euro 4 standards, it balances performance with drivability in high-end models.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 5,461 cc | |
| Fuel type | Petrol | |
| Configuration | 90° V8, DOHC, 32-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 96.9 mm × 92.4 mm | |
| Power output | 225–285 kW (306–388 PS) | |
| Torque | 460–530 Nm @ 2,700–4,000 rpm | |
| Fuel system | Sequential multi-port fuel injection | |
| Emissions standard | Euro 4 | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | N/A | |
| Timing system | Dual chain (primary and secondary), non-interference design | |
| Oil type | MB 229.5 (SAE 5W-40) | |
| Dry weight | 210 kg |
The naturally aspirated V8 provides linear power delivery ideal for relaxed cruising but requires adherence to 15,000 km oil service intervals to protect camshaft adjusters and hydraulic lifters. MB 229.5 (5W-40) oil is critical due to its shear stability and wear protection for high-load valve train components. Cold-start idling should be limited to 30 seconds to ensure prompt oil circulation. The intake manifold and throttle bodies are prone to carbon buildup after 100,000 km, requiring periodic cleaning to maintain idle stability. Post-2008 models feature updated cam phasers; pre-2008 units should follow SIB 07-2008-01 for inspection and replacement. Emissions systems rely on precise air metering—faulty MAF sensors can trigger catalyst efficiency codes.
Oil Specs: Requires MB 229.5 (5W-40) specification (Mercedes-Benz SIB 07-2008-01). Compatible with ACEA A3/B4.
Emissions: Euro 4 certification applies to all production years (2005–2011) (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Measured under DIN 70020 standards. 285 kW output applies to S 550/CL 550 variants (Mercedes-Benz TIS Doc. A001903).
Mercedes-Benz Technical Information System (TIS): Docs A001903, A005903, SIB 07-2008-01
VCA Type Approval Database (VCA/EMS/5678)
ISO 1585:1996 Road vehicles — Test code for net power of internal combustion engines
The Mercedes-Benz M 273.961 was used across Mercedes-Benz's W211/W221/R230 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-intake tuning for the SL-Class and revised engine mounts for the S-Class-and from 2008, updated camshaft adjusters were introduced to improve longevity, creating minor service part differences. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front-right cylinder bank near the intake manifold (Mercedes-Benz TIS A001903). The 8th VIN digit indicates engine type ('E' for M 273 series). Pre-2008 models have silver valve covers with 'M 273' engraving; post-2008 units use black valve covers. Critical differentiation from M 272: M 273.961 has a 90° V8 configuration with dual chain timing, while M 272 is a 90° V6. Service parts require production date verification—camshaft adjusters before 07/2008 are subject to wear and should be replaced per SIB 07-2008-01.
The M 273.961's primary reliability risk is camshaft adjuster wear in pre-2008 builds, with elevated incidence in vehicles with extended oil intervals. Internal Mercedes-Benz quality reports from 2009 indicated a significant number of pre-facelift engines required adjuster replacement before 120,000 km, while UK DVSA MOT data links a portion of engine-related failures to oil system neglect. Cold-start cycles and infrequent oil changes increase adjuster wear, making oil quality and interval adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2007-2012) and UK DVSA failure statistics (2010-2020). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M273961.
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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