Mercedes-Benz M137 Specifications
| Engine Model: Mercedes-Benz M133 |
| Engine Type: 4-cycle 12-cylinder SOHC 36-valve liquid-cooled gasoline |
| Total Displacement: 353.1 cu.in (5.78 L) |
| Rated Engine Power: 367 Hp (270 kW) at 5500 rpm |
| Fuel System Type: Sequential multi-point fuel injection |
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The Mercedes-Benz M137 is a 5.8-liter V12 gasoline
engine produced between 1998 and 2002, developed as a lightweight and compact
replacement for the M120 V12 that preceded it. Designed to meet the evolving
demands for reduced mass, improved packaging, and enhanced fuel efficiency in
the flagship S-Class and CL-Class models, the M137 represented a fundamental
departure from its predecessor’s architecture.
The engine was conceived alongside the M112 V6 and M113 V8 families, sharing
their modular design philosophy and utilizing a single overhead camshaft (SOHC)
per cylinder bank with a three-valve per cylinder arrangement - a configuration
that reduced complexity, lowered overall height, and decreased mass compared to
the four-valve M120.
The M137 incorporates a 60-degree V-angle and is constructed entirely from
aluminum alloys, with an Alusil cylinder block, aluminum cylinder heads, and a
magnesium intake manifold. A forged steel crankshaft provides the necessary
strength for the engine’s substantial torque output. The engine was offered in
standard form for the S 600 and CL 600 models, with a bored and stroked
6.3-liter version developed by AMG for limited-production high-performance
variants.
One of the M137’s most advanced features for its era was Active Cylinder
Management (ACC), a system that deactivated one complete cylinder bank under
light load to reduce fuel consumption, marking one of the first applications of
cylinder deactivation on a production V12 engine.
The M137 is a water-cooled, four-stroke, naturally aspirated V12 gasoline engine
configured for longitudinal mounting in rear-wheel-drive and all-wheel-drive
vehicle architectures. Its design emphasizes compact dimensions, reduced mass,
and operational refinement.
Engine Type: 60-degree V12, 4-cycle, water-cooled, naturally aspirated.
Displacement: 5,786 cc (353.1 cu.in).
Bore and Stroke: 84.0 mm (3.31 in) x 87.0 mm (3.43 in).
Compression Ratio: 10.0:1.
Valvetrain: SOHC, 3 valves per cylinder (2 intake, 1 exhaust) with chain drive.
Fuel System: Sequential multi-point fuel injection (MPI).
Firing Order: 1-12-5-8-3-10-6-7-2-11-4-9.
Maximum Power: 270 kW (367 Hp) at 5,500 rpm.
Maximum Torque: 530 Nm (391 lb-ft) at 4,250 rpm.
Idle Speed: 580 ± 30 rpm.
Engine Redline: 6,000 rpm.
The cylinder block is constructed from an
aluminum-silicon alloy utilizing the Alusil process, in which silicon particles
are dispersed throughout the aluminum matrix to create a wear-resistant cylinder
bore surface. This technology eliminates the need for cast iron cylinder liners,
reducing overall block mass while maintaining excellent wear characteristics.
The block features a 60-degree V-angle, a configuration selected for inherent
balance, compact width, and reduced vibration compared to narrower V-angles.
The closed-deck block design provides robust support for the cylinder head
gaskets and minimizes bore distortion under high thermal and mechanical loads.
The block incorporates seven main bearing webs with cross-bolted main bearing
caps, a design that enhances rigidity under the high bending and torsional loads
generated by the V12 configuration. The crankshaft is supported by seven main
bearings and is constructed from forged steel to withstand the engine’s
substantial torque output. An aluminum oil pan is sealed to the lower crankcase,
contributing to overall engine rigidity and serving as the oil reservoir.
Block Material: Aluminum-silicon alloy (Alusil).
Bore Diameter (finished): 84.0 mm (3.31 in).
Main Bearing Caps: Cast iron, cross-bolted design.
Cylinder Bore Deformation Limit: 0.03 mm (0.0012 in).
Crankshaft: Forged steel crankshaft with seven main bearings and twelve
counterweights.
Connecting Rods: Forged steel, fracture-split cap design.
Pistons: Cast aluminum alloy with a reinforced crown section and a low-friction
skirt coating.
Each cylinder head is manufactured from aluminum alloy,
with one head per cylinder bank. The SOHC valvetrain actuates three valves per
cylinder - two intake valves and one exhaust valve - through a system of roller
rocker arms. The three-valve configuration was selected to reduce cylinder head
width and overall engine height compared to a four-valve design, contributing to
the M137’s compact packaging while maintaining adequate flow characteristics for
the naturally aspirated application.
The camshafts are driven by a duplex roller chain from the crankshaft, with an
automatic hydraulic tensioner maintaining chain tension. Valve clearance is
maintained by hydraulic lash adjusters integrated into the roller rocker arms,
eliminating the need for manual adjustment throughout the engine’s service life.
The combustion chambers are of a compact pent-roof design, optimized for the
three-valve layout. The engine incorporates twin-spark ignition, with two spark
plugs per cylinder mounted on opposite sides of the combustion chamber. The
offset firing sequence of the two plugs enhances combustion efficiency, reduces
emissions, and allows for leaner air-fuel mixtures under partial load
conditions.
Head Material: Aluminum alloy.
Valve Configuration: SOHC, 3 valves per cylinder (2 intake, 1 exhaust) with
roller rocker arms and hydraulic lash adjusters.
Valve Diameter (Intake): 37.0 mm (1.46 in).
Valve Diameter (Exhaust): 38.0 mm (1.50 in) (single exhaust valve).
Valve Stem Diameter: 6.0 mm (0.24 in).
Valve Seat Angle: 45 degrees.
The M137 employs a sequential multi-point fuel
injection (MPI) system. This system uses twelve fuel injectors mounted in the
intake manifold, positioned to spray fuel directly onto the back of each intake
valve. The sequential injection strategy allows each injector to fire at the
optimal point in the intake cycle for its respective cylinder, improving fuel
economy and reducing emissions.
A fuel pump assembly located within the fuel tank supplies pressurized fuel to a
dual fuel rail system - one rail per cylinder bank - that distributes fuel
evenly to all twelve injectors. The engine control unit (ECU) calculates
injection pulse width based on input from the mass airflow sensors, throttle
position sensor, coolant temperature sensor, crankshaft position sensor, and
oxygen sensor feedback from both cylinder banks. The Active Cylinder Management
(ACC) system, active under light load conditions, shuts off fuel delivery to one
complete cylinder bank and deactivates the corresponding intake and exhaust
valves, allowing the engine to operate as a six-cylinder unit to reduce fuel
consumption.
Injection Type: Sequential multi-point electronic fuel injection (port
injection).
Fuel Pressure: 350-380 kPa (50.8-55.1 psi).
Fuel Injector Resistance: 12.0-16.0 Ohms.
Fuel Requirement: 95 Research Octane Number (RON) or higher (premium).
Fuel Cutoff: 6,200 rpm.
The lubrication system is a fully pressurized, wet-sump
design utilizing a gear-type oil pump mounted to the front of the crankshaft.
The oil pump draws lubricant from the aluminum oil pan through a mesh strainer
and circulates it through a full-flow, replaceable oil filter before entering
the main oil gallery. From the gallery, pressurized oil is distributed to the
crankshaft main bearings, connecting rod bearings, camshaft bearings, hydraulic
lash adjusters, and timing chain tensioners.
A pressure relief valve integrated into the oil pump maintains system pressure
within operational limits to prevent over-pressurization during cold starts or
high engine speeds. The lubrication system includes oil jets directed at the
underside of each piston crown to manage thermal loads. An oil cooler is mounted
within the V of the engine block to maintain oil temperature under sustained
high-load conditions.
Oil Type: Synthetic, SAE 0W-40, 5W-40, or 10W-40.
Oil Capacity (with filter): 9.0-9.5 liters (9.5-10.0 US qt).
Oil Pressure (at 3,000 rpm): 350-450 kPa (50.8-65.3 psi).
Oil Pump Type: Gear-type, crankshaft-driven.
Oil Filter Type: Cartridge-type, replaceable element.
The cooling system is a pressurized, liquid-cooled
design employing a cross-flow aluminum radiator with dual electric cooling fans.
A centrifugal-type water pump, driven by the crankshaft, circulates coolant
through the engine block, cylinder heads, heater core, and transmission oil
cooler. A wax-pellet thermostat regulates coolant flow to maintain optimal
operating temperature, with a bypass circuit that allows the engine to warm
rapidly by circulating coolant only within the engine until the thermostat
opens.
The cooling system is sized to manage the thermal load generated by the V12
configuration. An auxiliary electric water pump continues coolant circulation
after engine shutdown to prevent localized hot spots and protect the
turbocharger bearings on the AMG variants.
Coolant Type: Ethylene-glycol based antifreeze with corrosion inhibitors.
Coolant Capacity: 13.0-14.0 liters (13.7-14.8 US qt).
Thermostat Opening Temperature: 85-90 °C (185-194 °F).
Thermostat Full-Open Temperature: 102 °C (216 °F).
Radiator Cap Pressure: 140-150 kPa (20.3-21.8 psi).
Water Pump Type: Centrifugal, crankshaft-driven.
| Intake and Exhaust Systems |
Intake System: A magnesium intake manifold with two
separate plenums - one per cylinder bank - and a crossover passage to balance
intake pulsations. The intake system incorporates an air cleaner housing with a
dry-type paper filter element. An electronically controlled throttle body
manages airflow into the engine.
Exhaust System: Stainless steel exhaust manifolds with individual runners per
cylinder bank collecting into dual downpipes. The system incorporates four
heated oxygen sensors (two upstream, two downstream of the catalytic converters)
for precise fuel trim feedback per cylinder bank. Dual catalytic converters are
integrated into the exhaust system.
Twin-spark ignition with two individual pencil-type
ignition coils per cylinder, mounted directly over each spark plug. The system
utilizes a crankshaft position sensor and two camshaft position sensors (one per
cylinder bank) for precise ignition timing control. The offset firing sequence
between the two spark plugs per cylinder enhances combustion stability and
allows for retarded ignition timing under cold-start conditions to rapidly heat
the catalytic converters.
Active Cylinder Management (ACC): The ACC system
deactivates one complete cylinder bank under light-load conditions. When active,
fuel injection is halted for the deactivated bank, and the intake and exhaust
valves are held closed by hydraulic valve deactivation mechanisms integrated
into the roller rocker arms. The system operates seamlessly, with transition
between six-cylinder and twelve-cylinder operation controlled by the ECU based
on throttle position, engine load, and vehicle speed.
Timing Drive: A duplex roller chain drives the camshafts from the crankshaft.
The primary chain drives an intermediate shaft, with secondary chains from that
shaft driving the left and right cylinder bank camshafts. Automatic hydraulic
tensioners maintain chain tension. The timing system is designed for the service
life of the engine with no specified replacement interval under normal operating
conditions.
Overall Length: 780 mm (30.7 in)
Overall Width: 850 mm (33.5 in)
Overall Height: 680 mm (26.8 in)
Dry Weight (complete engine): 220 kg (485 lb)
Oil Change Interval: Variable, up to 20,000 km (12,500
mi) or 1 year under normal driving conditions; reduced under severe conditions.
Oil Filter Change: At every oil change. Engine Coolant Replacement: 150,000 km
(93,000 mi) or 10 years; thereafter 60,000 km (37,500 mi) or 5 years. Fuel
Filter Replacement: 80,000 km (50,000 mi).
Spark Plug Replacement: 80,000 km (50,000 mi). Spark Plug Type: NGK IFR6J-11 or
equivalent (iridium-tipped). Spark Plug Gap: 1.0-1.1 mm (0.039-0.043 in). Drive
Belt (Accessory) Inspection: Every 20,000 km (12,500 mi) for tension, cracking,
and glazing. Air Filter Replacement: 40,000 km (25,000 mi) or as indicated by
inspection.
Cylinder Head Bolts (M12 x 1.5), 1st pass: 40 Nm (30
lb-ft).
Cylinder Head Bolts (M12 x 1.5), 2nd pass: 60 Nm (44 lb-ft) plus 90° rotation.
Main Bearing Cap Bolts (M12 x 1.5): 50 Nm (37 lb-ft) plus 90° rotation.
Connecting Rod Cap Bolts (M9 x 1.0): 20 Nm (15 lb-ft) plus 90° rotation.
Camshaft Bearing Cap Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Intake Manifold Bolts (M8 x 1.25): 20-25 Nm (15-18 lb-ft).
Exhaust Manifold Nuts (M8 x 1.25): 25-30 Nm (18-22 lb-ft).
Spark Plugs: 25-28 Nm (18-21 lb-ft).
Oil Pan Bolts (M6 x 1.0): 9-11 Nm (80-97 lb·in).
Water Pump Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Timing Chain Tensioner (M14 x 1.5): 40-45 Nm (30-33 lb-ft).
Crankshaft Pulley Bolt (M18 x 1.5): 200 Nm (148 lb-ft).
Flywheel / Drive Plate Bolts (M12 x 1.5): 90-100 Nm (66-74 lb-ft) plus 90°
rotation.
The Mercedes-Benz M137 engine was utilized across the
flagship model lines of the Mercedes-Benz passenger vehicle range during its
production period from 1998 to 2002, with limited-production AMG variants
appearing during the final years of the engine’s lifecycle.
S-Class (W220): S 600 (1998-2002 model years).
CL-Class (C215): CL 600 (1998-2002 model years).
S-Class (W220): S 63 AMG (2001-2002, limited production).
CL-Class (C215): CL 63 AMG (2001-2002, limited production).
G-Class (W463): G 63 AMG (2002-2003, low-volume V12 variant).
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