The Mercedes-Benz M116.961 is a 3,839 cc, naturally aspirated V8 petrol engine produced between 1981 and 1991. It features a 90° V8 configuration with a cast-iron block, aluminium heads, and dual overhead camshafts (DOHC) per bank. Delivering 150 kW (204 PS) at 5,000 rpm and 315 Nm of torque at 3,750 rpm, it was engineered for smooth, refined performance in luxury grand tourers and sedans.
Fitted primarily to the W126 S-Class and R107 SL-Class, the M116.961 was designed to provide effortless power delivery and long-distance cruising capability. It met Euro 1 emissions standards through precision mechanical fuel injection (Bosch K-Jetronic) and exhaust gas recirculation (EGR), with catalytic converter integration standard in most European and North American markets from 1985 onward.
One documented service concern involves degradation of the intake manifold vacuum flaps, which can lead to unstable idle and hesitation under light load. This issue, referenced in Mercedes Technical Service Bulletin 01.03.176, is typically caused by cracked diaphragms or blocked vacuum lines. Later production units incorporated revised vacuum actuators and updated flap linkage to improve long-term reliability.
Production years 1981–1984 meet pre-Euro emissions standards; 1985–1991 models comply with Euro 1 (EU Directive 83/351/EEC).
The Mercedes-Benz M116.961 is a 3,839 cc V8 naturally aspirated petrol engine engineered for full-size luxury sedans and grand tourers (1981–1991). It combines DOHC valvetrain architecture with Bosch K-Jetronic continuous fuel injection to deliver linear power delivery and smooth operation. Designed to meet early European emissions standards, it balances proven mechanical design with refined driving characteristics.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,839 cc | |
| Fuel type | Petrol | |
| Configuration | 90° V8, DOHC, 32-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 96.5 mm × 65.8 mm | |
| Power output | 150 kW (204 PS) @ 5,000 rpm | |
| Torque | 315 Nm @ 3,750 rpm | |
| Fuel system | Bosch K-Jetronic mechanical fuel injection | |
| Emissions standard | Pre-Euro (1981–1984); Euro 1 (1985–1991) | |
| Compression ratio | 9.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven camshafts (double-row) | |
| Oil type | SAE 10W-40 (API SF/CC) | |
| Dry weight | 220 kg |
The M116.961 provides smooth, refined V8 performance ideal for grand touring but requires consistent maintenance to preserve fuel and vacuum system integrity. Use of SAE 10W-40 oil meeting API SF/CC specifications is essential for camshaft and lifter lubrication. Vacuum-operated intake flaps should be inspected every 30,000 km to prevent idle instability. Fuel distributor and warm-up regulator servicing every 60,000 km maintains optimal air-fuel metering. Original K-Jetronic systems are sensitive to fuel quality; use of high-octane petrol (RON 98) prevents knock and maintains long-term injector and accumulator performance. Coolant system integrity is critical—replace hoses and thermostat every 90,000 km to prevent overheating.
Oil Specs: Requires SAE 10W-40 API SF/CC specification (Mercedes SIB 01.03.176). Supersedes earlier mineral oil standards.
Emissions: Euro 1 certification applies to post-1985 models only (EU Directive 83/351/EEC). Pre-1985 units comply with national equivalents under Regulation 1503/74.
Power Ratings: Measured under DIN 70020 standards. Output consistent across all markets with catalytic converter.
Mercedes-Benz Technical Information System (TIS): Docs A11670, M116-003, SIB 01.03.176
European Commission: Directive 83/351/EEC
SAE International: DIN 70020 Engine Power Measurement Standard
The Mercedes-Benz M116.961 was used across Mercedes-Benz's W126 and R107 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-fuel system tuning for automatic vs manual transmission pairings-and from 1985 the updated W126 models adopted Euro 1-compliant emission controls, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the front face of the right cylinder bank, near the timing cover (Mercedes TIS A11680). The 7th and 8th digits of the VIN indicate engine type ('16' for M116 series). Pre-1985 models lack catalytic converters in some markets; post-1985 units feature catalytic converters and revised exhaust routing. Critical differentiation from M117: M116.961 has a shorter stroke (65.8 mm vs 70.0 mm) and lower compression. Service parts require VIN and production date verification—intake manifold flaps and vacuum actuators for pre-1985 models are not compatible with Euro 1 variants due to calibration differences (Mercedes SIB 01.03.176).
The M116.961's primary reliability risk is vacuum flap actuator failure, with elevated incidence in high-mileage or poorly maintained vehicles. Mercedes internal service data from 1987 reported over 25% of pre-1985 units exhibiting idle instability by 150,000 km, while EU field reports link a significant share of drivability complaints to degraded vacuum lines. Extended idle periods and exposure to underhood heat accelerate diaphragm wear, making regular inspection and use of OEM-specified hoses critical.
Analysis derived from Mercedes-Benz technical bulletins (1981-1991) and EU vehicle field reliability reports (1985-1995). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M116961.
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