Mercedes-Benz OM654 Specifications
| Engine Model: Mercedes-Benz OM654 |
| Engine Type: 4-cycle 4-cylinder DOHC 16-valve turbocharged liquid-cooled diesel |
| Total Displacement: 119 cu.in (1.95 L) |
| Rated Engine Power: 122-194 Hp (90-143 kW) at 4000 rpm |
| Fuel System Type: Common rail direct injection |
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The Mercedes-Benz OM654 is a 2.0-liter inline-four
diesel engine introduced in 2016 as a clean-sheet design intended to replace the
long-serving OM651 four-cylinder diesel family. Developed under the company’s
modular engine architecture strategy, the OM654 represented a fundamental
departure from its predecessor, utilizing an all-aluminum block construction for
the first time in a Mercedes-Benz four-cylinder diesel.
This weight reduction initiative alone reduced engine mass by 17 percent
compared to the cast-iron OM651, contributing to improved vehicle dynamics and
lower fuel consumption. The engine’s architecture was engineered with a
rear-mounted timing chain system positioned at the flywheel end, a configuration
that reduces overall engine height to improve pedestrian safety impact
performance while simultaneously reducing mechanical noise transmitted to the
passenger compartment.
The OM654 was designed from the outset to accommodate a range of outputs through
varying turbocharger configurations and software calibrations, allowing it to
serve applications from the C-Class sedan through to the heavy-duty Sprinter
van. Its introduction coincided with the rollout of increasingly stringent Euro
6d emissions standards, and the engine incorporates an integrated emissions
aftertreatment system mounted directly to the engine block to achieve rapid
thermal management and efficient NOx reduction.
The OM654 engine embodies Mercedes-Benz’s shift toward platform consolidation
and emissions-focused engineering in the modern diesel era. Its all-aluminum
crankcase, featuring twin-wire arc-sprayed NANOSLIDE cylinder coating,
eliminates the need for conventional cast-iron liners while providing a
low-friction, wear-resistant bore surface. The engine’s compact dimensions are
achieved through the rear-mounted timing drive, which shortens the overall
length and permits a lower hood line in vehicle applications.
Thermal management is enhanced through a split cooling system that isolates the
cylinder head from the block during warm-up, accelerating combustion chamber
temperature rise and reducing internal friction during cold-start operation. The
combustion system utilizes stepped-bowl steel pistons - an unusual pairing with
an aluminum block - selected for their superior thermal stability and ability to
withstand the high peak cylinder pressures generated by the common-rail
injection system operating at up to 2,500 bar.
The OM654’s modular nature extends to its emissions architecture, with a
close-coupled aftertreatment system that includes a diesel oxidation catalyst,
diesel particulate filter, and selective catalytic reduction (SCR) unit all
mounted directly to the engine rather than distributed along the underbody. This
integrated approach ensures rapid light-off of catalysts after a cold start, a
critical factor for meeting real-world driving emissions standards. The engine’s
refinement level is notable for a four-cylinder diesel, with the rear timing
chain and careful structural tuning contributing to noise, vibration, and
harshness characteristics that rival larger-displacement six-cylinder engines.
Production Period: 2016-present.
Engine Code: OM654 (DE 20).
Configuration: Inline-four (I4).
Displacement: 1,950 cc (119.0 cu.in).
Bore: 82.0 mm (3.23 in).
Stroke: 92.3 mm (3.63 in).
Firing Order: 1-3-4-2.
Compression Ratio: 15.5:1.
Maximum Engine Speed: 5,200 rpm (governed).
Engine Weight: 168.4 kg (371 lbs) complete.
Power Output
OM654 DE 20 G LR (Low Output): 122 hp (90 kW) @ 3,200-4,600 rpm.
OM654 DE 20 (Standard Output): 150 hp (110 kW) @ 3,200-4,600 rpm.
OM654 DE 20 (High Output): 194 hp (143 kW) @ 3,800 rpm.
OM654 M (Mild Hybrid): 265 hp (195 kW) from combustion engine.
Max Torques
OM654 DE 20 G LR (Low Output): 221 lb-ft (300 Nm) @ 1,400-3,200 rpm.
OM654 DE 20 (Standard Output): 236 lb-ft (320 Nm) @ 1,400-3,200 rpm.
OM654 DE 20 (High Output): 295 lb-ft (400 Nm) @ 1,600-2,800 rpm.
OM654 M (Mild Hybrid): 406 lb-ft (550 Nm) combined.
The OM654 cylinder block is constructed from a
high-pressure die-cast aluminum alloy, marking a significant departure from the
cast-iron construction of its predecessor. The block incorporates the NANOSLIDE
cylinder bore coating, applied using a twin-wire arc spray process that deposits
a thin layer of iron-carbon alloy onto the aluminum bore surfaces.
This coating is subsequently honed to create a mirror-smooth surface with
microscopic cavities that retain oil, reducing friction by approximately 50
percent compared to conventional cast-iron liners while providing wear
resistance superior to traditional materials. The block features a closed-deck
design at the top of the cylinder bores to maximize rigidity under high cylinder
pressures that exceed 180 bar.
The main bearing caps are made from sintered steel and are integrated into a
bedplate structure that also serves as the lower crankcase, contributing to
overall engine stiffness. The crankshaft centerline is offset by 12 mm (0.47 in)
relative to the cylinder bore centerline, a design feature that reduces the
piston side-loading during the power stroke and contributes to lower mechanical
friction. The block incorporates the engine’s split cooling system with separate
coolant passages for the cylinder head and block.
The cylinder head is manufactured from cast aluminum
alloy and features a dual-overhead-camshaft (DOHC) arrangement with four valves
per cylinder. The valvetrain utilizes roller finger followers with hydraulic
lash adjusters, eliminating any requirement for manual valve clearance
maintenance. The valve diameters are 29.5 mm (1.16 in) for the intake valves and
26.0 mm (1.02 in) for the exhaust valves.
The camshafts are hollow to reduce rotational mass and are driven by a
single-stage timing chain located at the rear of the engine, adjacent to the
flywheel. This rear-chain configuration allows for a shorter engine length and
reduces the transmission of timing chain noise to the front of the vehicle.
The cylinder head incorporates integrated exhaust manifolds cast directly into
the head structure, a design that reduces exhaust gas heat loss to the coolant
during warm-up and accelerates the heating of the aftertreatment system. The
combustion chamber is designed around centrally located multi-hole injectors,
with the piston bowl geometry optimized to promote air-fuel mixing for complete
combustion.
The OM654 utilizes a fourth-generation common-rail
direct injection system supplied by Bosch. The system operates at maximum
injection pressure of 2,500 bar (36,260 psi), delivered by a high-pressure pump
mounted to the engine and driven by the rear timing chain system. The fuel rail
is of a single-pass design, with pressure sensors providing feedback to the
engine control unit for closed-loop pressure regulation.
Piezoelectric injectors, capable of performing up to eight injection events per
combustion cycle, enable multiple pilot injections, a main injection, and
post-injections for particulate filter regeneration. The injection system is
capable of varying injection timing, pressure, and quantity on a cycle-by-cycle
basis, allowing precise control over combustion noise, emissions formation, and
fuel consumption.
A fuel cooler is integrated into the system to maintain fuel temperature within
an optimal range, particularly important for the high-pressure pump’s longevity
and consistent injection quantity control. The system uses a returnless fuel
delivery architecture, with the pressure regulator located within the fuel tank
to reduce fuel heating and evaporative emissions.
The lubrication system employs a variable-displacement
vane-type oil pump mounted within the front engine cover and driven directly by
the crankshaft. The pump’s displacement is controlled by the engine control unit
based on operating conditions, reducing parasitic losses by delivering only the
oil volume required for current engine speed and load.
At low engine speeds, the pump operates at maximum displacement to ensure
adequate flow, while at higher speeds, displacement is reduced to maintain
pressure without excess flow. The oil cooler is integrated with the oil filter
housing in a water-to-oil configuration, using engine coolant to stabilize oil
temperature. The oil filter is a replaceable cartridge type with an integrated
bypass valve to ensure lubrication continuity in the event of filter
restriction.
Total system capacity, including the oil cooler and filter, is 6.5 liters (6.9
qt) for most passenger car applications. The engine utilizes low-viscosity
synthetic oil, specified to 0W-20 grade, to reduce cold-start friction and
improve fuel economy.
The cooling system employs a split-circuit design,
separating coolant flow to the cylinder block and cylinder head. A
map-controlled thermostat and an electric coolant pump, in certain applications,
allow the engine control unit to manage coolant flow independently of engine
speed. During cold start conditions, coolant circulation is restricted to the
cylinder head only, allowing the cylinder block to warm up more rapidly and
reducing internal friction. Once operating temperature is reached, the system
opens flow to the radiator and cylinder block.
The main radiator is a high-efficiency aluminum unit with plastic end tanks,
complemented by an electric cooling fan controlled via pulse-width modulation
for variable speed operation. An additional electric coolant pump is employed on
vehicles equipped with the mild hybrid system to provide cabin heating and
aftertreatment thermal management when the combustion engine is not running. The
system utilizes a degas bottle with a pressure cap rated at 1.4 bar (20 psi).
Total coolant capacity ranges from 9.0 to 10.5 liters (9.5 to 11.1 qt) depending
on vehicle platform and equipment.
The intake system varies by output variant, with
lower-output versions utilizing a single variable-nozzle turbocharger (VNT) with
fixed geometry intake manifold. Higher-output variants employ a two-stage
turbocharging system with a smaller high-pressure turbocharger and a larger
low-pressure turbocharger arranged in series, providing rapid boost response at
low engine speeds while delivering high airflow at upper rpm ranges. An
air-to-air intercooler is mounted ahead of the radiator to reduce intake air
temperature and increase charge density.
The engine management system utilizes a Bosch engine
control unit with integrated processing for injection, turbocharger control, and
aftertreatment management. The system monitors a comprehensive array of sensors,
including wideband oxygen sensors, particulate filter differential pressure
sensors, and multiple temperature sensors throughout the intake and exhaust
systems. On mild hybrid variants, a belt-driven starter-generator provides 20 hp
(15 kW) of electric assistance during acceleration and enables functions
including coasting with the engine off and regenerative braking energy recovery.
Exhaust Aftertreatment System: The OM654 features an
integrated emissions aftertreatment module mounted directly to the engine block.
This module combines a diesel oxidation catalyst (DOC), a diesel particulate
filter (DPF), and a selective catalytic reduction (SCR) catalyst with an ammonia
slip catalyst (ASC). The close-coupled position of the aftertreatment system
reduces the time required to reach operating temperature after cold start, a
critical factor for meeting real-world emissions regulations. AdBlue (diesel
exhaust fluid) is injected into the exhaust stream upstream of the SCR catalyst,
with the system incorporating a heated AdBlue delivery line to prevent
crystallization in cold climates.
Timing Drive: The timing chain is located at the rear of the engine, adjacent to
the transmission bell housing. This arrangement reduces the overall engine
length and contributes to lower noise emissions at the front of the vehicle. The
chain drives both camshafts and the high-pressure fuel pump, with a hydraulic
tensioner maintaining proper chain tension throughout the engine’s operating
range.
Overall Length: 580 mm (22.8 in)
Overall Width: 680 mm (26.8 in)
Overall Height: 640 mm (25.2 in)
Dry Weight (complete engine): 168.4 kg (371 lbs)
Engine Oil: Synthetic 0W-20 meeting Mercedes-Benz
specification 229.71 (MB 229.71) for low-SAPS (sulfated ash, phosphorus, sulfur)
compatibility. Oil Capacity (with filter change): 6.5 L (6.9 qt). Oil Change
Interval: 30,000 km (18,600 mi) or 2 years under normal conditions; 15,000 km
(9,300 mi) under severe service.
Spark Plug: Not applicable (compression-ignition engine). Fuel Filter: Replace
at 40,000 km (24,800 mi) intervals; water drain service as indicated by warning
light. Coolant Capacity: 9.0-10.5 L (9.5-11.1 qt) depending on platform. Coolant
Specification: Mercedes-Benz approved phosphate-free, silicate-free antifreeze
meeting specification 325.0 or 326.0.
Valve Clearance: Hydraulic lash adjusters; no adjustment required. Engine Idle
Speed: 650-750 rpm. Glow Plugs: Ceramic glow plugs with afterglow function;
replacement interval 120,000 km (74,500 mi). AdBlue Consumption: 1.5-2.0 L per
1,000 km (0.4-0.5 gal per 600 mi) depending on driving conditions.
Tightening Torques (Critical Fasteners)
Connecting Rod Cap Bolts (M9 x 1): 30 Nm (22 lb-ft) + 90° + 90°
Main Bearing Cap Bolts (M10 x 1.25): 50 Nm (37 lb-ft) + 90° + 90°
Cylinder Head Bolts (M10), Stage 1: 40 Nm (30 lb-ft)
Cylinder Head Bolts (M10), Stage 2: 80 Nm (59 lb-ft)
Cylinder Head Bolts (M10), Stage 3: 120 Nm (89 lb-ft)
Camshaft Bearing Caps (M6 x 1): 10 Nm (7 lb-ft)
Camshaft Bearing Caps (M8 x 1.25): 23 Nm (17 lb-ft)
Intake Manifold to Cylinder Head: 10 Nm (7 lb-ft)
Exhaust Manifold to Cylinder Head: 23 Nm (17 lb-ft) + 90°
Flywheel/Flexplate to Crankshaft (M12): 100 Nm (74 lb-ft) + 90° + 90°
High-Pressure Fuel Pump Mounting: 23 Nm (17 lb-ft) for M8
High-Pressure Fuel Pump Mounting: 10 Nm (7 lb-ft) for M6
Fuel Rail Mounting Bolts: 23 Nm (17 lb-ft)
Turbocharger Mounting Nuts: 45 Nm (33 lb-ft)
Oil Filter Housing to Block: 23 Nm (17 lb-ft)
Mercedes-Benz Passenger
Cars
W205 C-Class (2016-2021): C 200 d, C 220 d, C 300 d.
W206 C-Class (2021-present): C 200 d, C 220 d, C 300 d.
W213 E-Class (2016-2023): E 200 d, E 220 d, E 300 d.
W214 E-Class (2023-present): E 220 d, E 300 d.
W223 S-Class (2020-present): S 350 d (select markets).
W222 S-Class (facelift, 2017-2020): S 350 d (select markets).
Mercedes-Benz SUVs and Crossovers
X253 GLC-Class (2016-2022): GLC 200 d, GLC 220 d, GLC 300 d.
X254 GLC-Class (2022-present): GLC 200 d, GLC 220 d, GLC 300 d.
V167 GLE-Class (2019-present): GLE 300 d, GLE 350 de (plug-in hybrid).
X247 GLB-Class (2019-present): GLB 200 d, GLB 220 d.
H247 GLA-Class (2020-present): GLA 200 d, GLA 220 d.
Mercedes-Benz Commercial Vehicles
W907/W910 Sprinter (2018-present): 210 CDI, 310 CDI, 410 CDI, 211 CDI, 311 CDI,
411 CDI, 213 CDI, 313 CDI, 413 CDI, 314 CDI, 414 CDI, 315 CDI, 415 CDI, 317 CDI,
417 CDI, 319 CDI, 419 CDI (varying power outputs).
W447 Vito / V-Class (2016-present): 111 CDI, 114 CDI, 116 CDI, 119 CDI, 124 CDI,
V 220 d, V 250 d, V 300 d.
Other Applications
Mercedes-Benz CLS-Class (C257): CLS 220 d, CLS 300 d (select markets).
Mercedes-Benz E-Class All-Terrain (S213): E 220 d, E 300 d.
Mercedes-Benz G-Class (W463A): G 350 d (2019-present, utilizing OM656
six-cylinder; OM654 not used in G-Class).
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