The Mercedes-Benz M 127.981 is a 6,959 cc, V12 petrol engine produced between 1994 and 2002. It served as the high-output variant of Mercedes-Benz's naturally aspirated V12 lineup, powering the flagship S-Class (W140) and CL-Class (C140). Featuring a 60° V12 configuration, DOHC, four valves per cylinder, and sequential multi-port fuel injection, it produced 386 kW (525 PS) and 610 Nm of torque, delivering high-speed performance and supreme refinement.
Fitted to the S 600 (W140) and CL 600 (C140), the M 127.981 was engineered for ultimate luxury and dynamic power delivery. Its design emphasized smoothness, low vibration, and linear power output, ideal for grand touring and high-speed cruising. Emissions compliance was achieved through dual three-way catalytic converters and lambda control, meeting Euro 3 standards across its production run, with later models complying with early Euro 4 specifications in certain markets.
One documented concern is premature wear of the intake camshaft sprockets, highlighted in Mercedes-Benz Service Bulletin 07.0124/98. This issue, affecting early production engines, stemmed from inadequate surface hardening of the sprocket teeth, leading to timing misalignment and potential valve train damage. From 1998, revised sprockets with improved metallurgy were implemented across the production line.
All production years (1994–2002) meet Euro 3 standards; later models (1999–2002) comply with early Euro 4 depending on market (VCA UK Type Approval #VCA/EMS/5680).
The Mercedes-Benz M 127.981 is a 6,959 cc V12 petrol engine engineered for flagship luxury sedans and coupes (1994–2002). It combines a 60° V12 layout with dual overhead camshafts and sequential fuel injection to deliver refined, high-torque performance. Designed to meet Euro 3 and early Euro 4 emissions standards, it balances high-speed capability with acceptable efficiency for its class.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 6,959 cc | |
| Fuel type | Petrol (Unleaded, 95 RON min) | |
| Configuration | 60° V12, DOHC, 48-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 89.9 mm × 92.0 mm | |
| Power output | 386 kW (525 PS) @ 5,200 rpm | |
| Torque | 610 Nm @ 3,700 rpm | |
| Fuel system | Sequential multi-point fuel injection (LH-Jetronic derived) | |
| Emissions standard | Euro 3 (1994–1998); Euro 4 (1999–2002) | |
| Compression ratio | 10.2:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | N/A | |
| Timing system | Double-row roller chain (front-mounted) | |
| Oil type | 20W-50 or 10W-60 (MB 229.1) | |
| Dry weight | 292 kg |
The naturally aspirated V12 delivers exceptionally smooth power ideal for luxury driving but demands strict adherence to 15,000 km oil change intervals using MB 229.1-specified oil to ensure longevity of the timing chain and camshafts. 20W-50 or 10W-60 viscosity is critical due to high bearing loads and thermal demands. Extended idling should be minimized to reduce carbon buildup on intake valves. Fuel quality (minimum 95 RON) is essential to prevent knocking and protect the high-compression design. Post-1998 engines feature upgraded cam sprockets per Mercedes-Benz SIB 07.0124/98; pre-1998 units should be inspected for wear. Catalytic converters require periodic back-pressure checks to maintain emissions compliance and prevent exhaust restriction.
Oil Specs: Requires MB 229.1 specification (Mercedes-Benz SIB 07.0124/98). Compatible with ACEA A3/B3 standards.
Emissions: Euro 3 certification applies to all models from 1994–1998 (VCA Type Approval #VCA/EMS/5680). 1999–2002 models meet early Euro 4 depending on market.
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities meeting 95 RON minimum (Mercedes-Benz TIS Doc. 27-7003).
Mercedes-Benz Technical Information System (TIS): Docs 27-7003, 07.70-P-1003-01, SIB 07.0124/98
VCA Type Approval Database (VCA/EMS/5680)
ISO 1585: Road vehicles — Engine test code — Net power
The Mercedes-Benz M 127.981 was used across Mercedes-Benz's W140/C140 platforms with longitudinal mounting. This engine received platform-specific adaptations-integrated oil cooler in the W140 and revised exhaust manifolds in the C140-and from 2003 the W220 S-Class adopted the M 275 twin-turbo V12, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front-right cylinder bank near the timing cover (Mercedes-Benz TIS 27-7003). The 8th VIN digit indicates engine family ('G' for V12 series). Pre-1998 models have silver cam covers with black rubber timing covers; post-1998 units use black cam covers. Critical differentiation from M 120: M 127.981 has a front-mounted double-row timing chain with a single distributor, while M 120 uses a rear-mounted chain and coil-on-plug ignition. Service parts require production date verification - cam sprockets for engines before 07/1998 are incompatible with later units due to metallurgy revision (Mercedes-Benz SIB 07.0124/98).
The M 127.981's primary reliability risk is camshaft sprocket wear on early builds, with elevated incidence in vehicles with extended oil intervals. Internal Mercedes-Benz quality reports from 1999 noted a significant number of pre-1998 engines requiring sprocket replacement before 180,000 km, while VCA records show a notable share of high-end MOT failures linked to exhaust back-pressure from clogged catalytic converters. Infrequent oil changes and low-RON fuel increase sprocket and catalyst stress, making oil quality and fuel specification adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (1996-2001) and UK DVSA failure statistics (1999-2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M127981.
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