Mercedes-Benz M272 Specifications
| Engine Model: Mercedes-Benz M272 |
| Engine Type: 4-cycle 6-cylinder DOHC 24-valve liquid-cooled gasoline |
| Total Displacement: 152.3-213.5 cu.in (2.49-3.49 L) |
| Rated Engine Power: 201-312 Hp (150-230 kW) at 5000 rpm |
| Fuel System Type: Multi-point fuel injection or direct injection |
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The Mercedes-Benz M272 is a naturally aspirated
90-degree V6 gasoline engine that served as the core of the mid-range
Mercedes-Benz lineup from its introduction in 2004 through its phase-out in
2011. Designed as the successor to the single-overhead-camshaft,
3-valve-per-cylinder M112, the M272 represented a fundamental shift in
Mercedes-Benz’s engineering approach for its V6 family.
It reintroduced a 4-valve-per-cylinder architecture, a configuration not used in
Mercedes-Benz six-cylinder engines since the M103’s early developments, and
incorporated a suite of advanced technologies aimed at delivering higher
specific output, improved fuel efficiency, and reduced emissions. The engine
family was defined by its all-aluminum construction utilizing Alusil cylinder
bore material, a sophisticated dual-stage variable intake manifold, and
continuous variable valve timing on both the intake and exhaust camshafts.
A notable engineering challenge arose from the engine’s 90-degree bank angle - a
design carried over from the V8 architecture to streamline production - which
required the incorporation of a balance shaft within the engine block to
counteract the inherent second-order vibrations of a 90-degree V6. This engine
architecture laid the groundwork for the later direct-injection CGI variants,
which further advanced the platform’s efficiency and power output before its
eventual replacement by the M276 engine family.
The M272 engine family arrived as a comprehensive technological package designed
to compete with the advanced V6 engines from BMW and Audi that dominated the
luxury mid-size segment in the mid-2000s. Its core innovation lies in the
cylinder head design, which utilizes a four-valve arrangement with centrally
positioned spark plugs and variable valve timing on both camshafts, allowing for
a remarkably broad torque curve and a free-revving character.
The dual-stage intake manifold, controlled by a set of pneumatic actuators and
tumble flaps, optimizes airflow velocity across the engine speed range,
contributing to a linear power delivery that belies its displacement. The
90-degree architecture, while necessitating a balance shaft for refinement,
provided inherent packaging advantages and allowed the engine to be manufactured
alongside Mercedes-Benz’s V8 engines on the same production lines. The M272
proved versatile, appearing in everything from compact C-Class sedans to the
flagship S-Class and the ML-Class SUV.
While its mechanical foundation is robust, the engine gained notoriety for
specific component failures, particularly involving the balance shaft gear
material on early production units and the plastic linkage for the intake
manifold tumble flaps. Despite these service considerations, the M272 remains a
significant powerplant that successfully modernized Mercedes-Benz’s six-cylinder
offerings and established a performance benchmark for the brand’s mid-range
models during its production run.
Production Period: 2004-2011.
Engine Codes: M272 (E25, E30, E35 variants).
Configuration: 90° V6.
Displacement (E25): 2,496 cc (152.3 cu.in).
Displacement (E30): 2,996 cc (182.8 cu.in).
Displacement (E35): 3,498 cc (213.5 cu.in).
Bore (E25/E30): 88.0 mm (3.46 in).
Bore (E35): 92.9 mm (3.66 in).
Stroke (E25): 68.4 mm (2.69 in).
Stroke (E30): 82.1 mm (3.23 in).
Stroke (E35): 86.0 mm (3.39 in).
Firing Order: 1-4-3-6-2-5.
Compression Ratio (E25): 11.2:1.
Compression Ratio (E30): 11.3:1.
Compression Ratio (E35): 10.7:1.
Maximum Engine Speed: 6,500 rpm (electronically limited).
Power Output
M272 E25 (2.5L): 201 hp (150 kW) @ 6,000 rpm.
M272 E30 (3.0L): 228 hp (170 kW) @ 6,000 rpm.
M272 E35 (3.5L Standard): 268 hp (200 kW) @ 6,000 rpm.
M272 E35 CGI (Direct Injection): 288-312 hp (215-230 kW) @ 6,800 rpm.
Max Torque
M272 E25 (2.5L): 181 lb-ft (245 Nm) @ 2,900-5,500 rpm.
M272 E30 (3.0L): 221 lb-ft (300 Nm) @ 2,500-5,000 rpm.
M272 E35 (3.5L Standard): 258 lb-ft (350 Nm) @ 2,400-5,000 rpm.
M272 E35 CGI (Direct Injection): 269 lb-ft (365 Nm) @ 3,000-5,100 rpm.
The M272 cylinder block is a die-cast aluminum alloy
construction utilizing the Alusil (aluminum-silicon) material technology. This
eliminates the requirement for cast-iron cylinder liners; instead, the cylinder
bores are machined and then chemically etched to expose hard silicon crystals,
creating a low-friction, wear-resistant surface against which the aluminum
pistons operate directly. The block is a 90-degree V configuration, a geometry
shared with the company’s V8 engines to optimize manufacturing commonality. This
90-degree angle introduces second-order vibrations inherent to V6 engines, which
are addressed by a balance shaft mounted within the crankcase.
The balance shaft is chain-driven from the crankshaft and rotates at engine
speed, generating opposing forces to cancel the vertical vibrations. The
crankcase features a cross-bolted main bearing design, where each main bearing
cap is secured with four bolts - two vertical and two horizontal - providing
exceptional rigidity to the rotating assembly. The block incorporates a
structural aluminum oil pan that contributes to overall powertrain stiffness and
reduces noise, vibration, and harshness transmission into the vehicle chassis.
The cylinder heads are manufactured from aluminum alloy
and feature a dual-overhead-camshaft (DOHC) arrangement with four valves per
cylinder. The valve train utilizes roller finger followers with hydraulic lash
adjusters, eliminating any requirement for routine valve clearance maintenance.
The valve diameters vary by displacement, with the 3.5-liter engine utilizing
larger valves to support its increased cylinder volume. Continuous variable
valve timing is implemented on both the intake and exhaust camshafts, with
camshaft adjusters capable of altering timing by up to 40 degrees of crank
angle.
This independent adjustment allows the engine management system to optimize
valve overlap for idle stability, low-end torque, and high-end power without
compromise. The camshafts are hollow to reduce rotational mass and are driven by
a single-stage timing chain arrangement that routes from the crankshaft to the
balance shaft and then upward to the intake camshafts, with secondary chains
linking the intake to the exhaust camshafts on each cylinder head.
The M272 fuel system exists in two distinct
configurations. The standard version utilizes a sequential multipoint electronic
fuel injection system with fuel injectors positioned in the intake ports. This
system operates at a nominal pressure of 3.8 bar (55 psi) and uses a returnless
fuel delivery setup where the fuel pressure regulator is located within the fuel
tank, reducing fuel heating and evaporative emissions.
The later CGI (Stratified-Charge Gasoline Injection) variants, introduced on the
3.5-liter engine from 2006 onward, employ a direct injection system. In this
configuration, piezoelectric injectors are mounted directly in the cylinder
head, injecting fuel at pressures up to 200 bar (2,900 psi) directly into the
combustion chamber.
This permits stratified-charge operation under light load conditions, where a
lean air-fuel mixture is concentrated around the spark plug while the remainder
of the cylinder contains only air, substantially improving thermal efficiency
and fuel economy. The direct injection system also allows for a higher
compression ratio, contributing to increased power output.
The lubrication system utilizes a wet-sump design with
a single-stage oil pump mounted within the front timing cover and driven
directly by the crankshaft. The oil pump incorporates a flow-control valve to
regulate pressure and reduce parasitic losses at higher engine speeds. An
integrated oil cooler is mounted to the oil filter housing, utilizing engine
coolant to maintain oil temperature within an optimal range.
The system is designed to maintain consistent oil pressure across the engine’s
operating range, with the pressure relief valve set to open at approximately 4.5
bar (65 psi). The oil filter is a spin-on cartridge type with an integrated
bypass valve to ensure continued oil flow in the event of filter restriction.
Total system capacity, including the oil cooler and filter, is 8.0 liters (8.5
qt) for most applications, though this varies slightly depending on the vehicle
platform and oil pan configuration.
The cooling system is a pressurized, cross-flow design
utilizing a high-efficiency aluminum radiator with plastic end tanks. A single
electric cooling fan, controlled by the engine control unit via a pulse-width
modulated signal, provides variable airflow, allowing for precise temperature
management and reduced electrical consumption compared to multi-speed fans. The
water pump is driven by the serpentine accessory belt and features a composite
impeller designed for cavitation resistance.
The thermostat is a map-controlled unit, where the engine control unit can
actively regulate coolant temperature by varying the thermostat’s opening point.
This allows the system to maintain higher temperatures under light load for
reduced friction and improved fuel economy, then lower temperatures under high
load for increased power output and knock resistance. The system incorporates a
degas bottle with a pressure cap rated at 1.4 bar (20 psi).
| Intake and Exhaust Systems |
Intake System: The intake manifold is a two-piece
composite plastic construction that incorporates a dual-stage variable-length
runner system. Long runners are utilized at low engine speeds to enhance intake
air velocity and torque, while short runners are engaged at high engine speeds
to maximize volumetric efficiency and power output. The transition between
runner lengths is controlled by pneumatic actuators responding to engine control
unit commands. Tumble flaps are integrated into the intake manifold runners,
creating controlled air turbulence at low engine speeds to improve fuel
atomization and combustion stability.
Exhaust System: The exhaust system utilizes stainless steel construction with a
close-coupled catalytic converter mounted directly to each cylinder head,
allowing the catalysts to reach operating temperature rapidly for emissions
compliance. Four oxygen sensors - two upstream and two downstream of the
catalysts - provide the engine control unit with feedback for closed-loop fuel
control and catalyst monitoring.
| Ignition and Electrical System |
Ignition System: The ignition system is a coil-on-plug
design with individual pencil-style ignition coils mounted directly over each
spark plug. This eliminates high-tension ignition wires and provides maximum
spark energy with precise timing control. The system receives its crankshaft
position signal from a 60-2 toothed wheel mounted on the crankshaft, with
camshaft position sensors on each cylinder head providing cylinder
identification for sequential fuel injection and ignition.
Electrical System: The engine management system utilizes a Bosch ME 9.7 or ME
2.8 control unit depending on the vehicle platform and injection type. The
system monitors a comprehensive array of sensors, including wideband oxygen
sensors for precise air-fuel ratio control, knock sensors on each cylinder bank,
and multiple temperature and pressure sensors throughout the intake and cooling
systems.
Overall Length: 645 mm (25.4 in).
Overall Width: 720 mm (28.3 in).
Overall Height: 690 mm (27.2 in).
Dry Weight (complete engine): 174 kg (384 lbs) for standard configuration.
Dry Weight (complete engine): 178 kg (392 lbs) for CGI variants.
Engine Oil: Synthetic 5W-30, 5W-40, or 0W-40 meeting
Mercedes-Benz specification 229.3, 229.5, or 229.51 (for CGI). Oil Capacity
(with filter change): 8.0 L (8.5 qt). Oil Change Interval: 16,000 km (10,000 mi)
or 1 year under normal conditions; 8,000 km (5,000 mi) under severe service.
Spark Plug Type: NGK ILZKR7A or Bosch FR 7 NPP 332. Spark Plug Gap: 1.0 mm
(0.040 in). Spark Plug Change Interval: 80,000 km (50,000 mi). Engine Idle
Speed: 650-750 rpm.
Coolant Capacity: 9.0-10.5 L (9.5-11.1 qt) depending on vehicle platform.
Coolant Specification: Mercedes-Benz approved phosphate-free, silicate-free
antifreeze (Glysantin G05 or equivalent). Balance Shaft Timing: Critical
maintenance item requiring special alignment tools; incorrect timing causes
camshaft correlation faults.
Connecting Rod Cap Bolts (M8 x 1): 20 Nm (15 lb-ft) +
90° + 90°
Main Bearing Cap Bolts (M10): 50 Nm (37 lb-ft) + 90°
Balance Shaft Bearing Cap Bolts: 10 Nm (7 lb-ft) for M6
Balance Shaft Bearing Cap Bolts: 23 Nm (17 lb-ft) for M8
Cylinder Head Bolts (M10, 12-point), Stage 1: 40 Nm (30 lb-ft)
Cylinder Head Bolts (M10, 12-point), Stage 2: 80 Nm (59 lb-ft) +90°
Camshaft Bearing Caps: 10 Nm (7 lb-ft) for M6
Camshaft Bearing Caps: 23 Nm (17 lb-ft) for M8
Intake Manifold to Cylinder Head: 10 Nm (7 lb-ft)
Exhaust Manifold to Cylinder Head: 25 Nm (18 lb-ft)
Flywheel/Flexplate to Crankshaft (M12 x 1.25): 100 Nm (74 lb-ft) + 90°
Spark Plugs: 23 Nm (17 lb-ft)
Oil Filter Housing to Block: 25 Nm (18 lb-ft)
Timing Chain Tensioner: 50 Nm (37 lb-ft)
Mercedes-Benz Passenger
Cars
W203 C-Class (2004-2007): C230 (2.5L).
W204 C-Class (2007-2011): C230 (2.5L), C280/C300 (3.0L), C350 (3.5L).
W211 E-Class (2005-2009): E230 (2.5L), E280/E300 (3.0L), E350 (3.5L).
W212 E-Class (2009-2011): E300 (3.0L), E350 (3.5L), E350 CGI (3.5L DI).
W220 S-Class (2005-2006): S350 (3.5L).
W221 S-Class (2006-2011): S350 (3.5L), S350 CGI (3.5L DI).
R171 SLK-Class (2004-2011): SLK280 (3.0L), SLK350 (3.5L).
W164 ML-Class (2005-2011): ML350 (3.5L).
X164 GL-Class (2006-2011): GL350 (3.5L).
W251 R-Class (2005-2011): R350 (3.5L).
C219 CLS-Class (2005-2010): CLS280 (3.0L), CLS350 (3.5L).
W203/C209 Sport Coupe (2005-2008): C230 (2.5L), C350 (3.5L).
W906 Sprinter (2006-2011): 3500 (3.5L) for select markets.
Other Applications
Brabus: Various tuned versions of the M272 for Mercedes-Benz models, offering
power outputs up to 290 hp (216 kW) from the 3.5-liter engine.
Carlsson: Engine management recalibrations and performance upgrades for
M272-equipped Mercedes-Benz vehicles.
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