Mercedes-Benz OM647 Specifications
| Engine Model: Mercedes-Benz OM647 |
| Engine Type: 4-cycle inline 5-cylinder DOHC 20-valve turbocharged liquid-cooled diesel |
| Total Displacement: 163.8 cu.in (2.68 L) |
| Rated Engine Power: 154-156 Hp (115-116 kW) at 3800 rpm |
| Fuel System Type: Common-rail direct injection |
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The Mercedes-Benz OM647 engine is an
inline-five cylinder, common-rail direct injection turbocharged diesel
powerplant. It represents a significant technological leap from the
preceding OM612, featuring refined combustion, improved electronic
management, and enhanced emissions control. Introduced in 2002, this
engine was the final evolution of Mercedes-Benz's five-cylinder diesel
for passenger cars and light commercial vehicles.
The OM647 employs a cast iron cylinder block, an aluminum cylinder head
with four valves per cylinder, and a Bosch second-generation common-rail
injection system operating at 1600 bar. It is renowned for its smooth
operation, substantial low-end torque, fuel efficiency, and exceptional
durability. The engine incorporates a variable geometry turbocharger
(VGT) and a maintenance-free, hydraulic valve compensation system. The
OM647 is considered one of the most reliable modern diesel engines
produced by Mercedes-Benz, serving as a workhorse in Sprinter vans and a
refined power unit in E-Class sedans.
Engine family: Mercedes-Benz OM647.
Engine type: Inline-five cylinder, four-stroke diesel cycle,
turbocharged with common-rail direct injection.
Displacement: 2685 cc (163.8 cubic inches).
Bore: 88.0 mm (3.465 inches).
Stroke: 88.4 mm (3.480 inches).
Compression ratio: 18.0:1.
Maximum power output: 154 Hp (115 kW) at 3800 rpm for passenger car
applications (E 270 CDI). 156 Hp (116 kW) at 3800 rpm for commercial
vehicle applications.
Maximum torque output: 295 lb-ft (400 Nm) at 1600-2400 rpm for passenger
car versions. 243 lb-ft (330 Nm) at 1200-2400 rpm for lower-state
commercial variants.
Firing order: 1-2-4-5-3.
Engine orientation: Longitudinal or transverse, depending on
application.
Aspiration: Variable geometry turbocharger (VGT) with air-to-air
intercooler.
Fuel type: Ultra-low sulfur diesel fuel.
Recommended oil grade: SAE 5W-40 or 0W-40, meeting Mercedes-Benz
specification 229.5 or 229.51. Oil capacity: 7.5 liters (7.9 U.S.
quarts), including filter.
Coolant capacity: 10.5 liters (11.1 U.S. quarts).
The cylinder block is a rigid, grey cast iron casting. Its design
provides inherent strength and effective noise damping for diesel
combustion forces. The block incorporates five cylinder bores arranged
in line. The crankshaft is supported by six main bearings, a
configuration essential for smoothing the inherent vibrations of a
five-cylinder layout. The crankshaft is a forged steel component.
Main bearing caps are cast iron and secured with two vertical bolts
each. Connecting rods are forged from steel. Pistons are aluminum alloy,
with a toroidal combustion bowl machined directly into the crown to
facilitate the direct injection combustion process. The piston design
includes cooling channels fed by dedicated oil spray jets. Each piston
uses three rings: two chrome-plated compression rings and one
three-piece oil control ring.
The cylinder head is a cast aluminum alloy unit. It employs a dual
overhead camshaft (DOHC) layout, with each camshaft operating ten valves
(two intake and two exhaust per cylinder). The four-valve design
optimizes airflow and promotes efficient combustion. Valve actuation is
via roller rocker arms with hydraulic lash adjusters, providing
automatic, zero-maintenance valve clearance compensation.
The camshafts are driven by a single-stage silent chain from the
crankshaft. Chain tension is maintained by a hydraulic tensioner. Intake
valves are sized to maximize air charge. Exhaust valves feature rotated
seat rings to improve durability. Valve seats are hardened to withstand
the high temperatures of direct diesel injection.
The fuel system is a Bosch second-generation common-rail direct
injection system. This is a defining feature, where a high-pressure pump
supplies fuel to a common rail (accumulator) maintained at a constant
pressure up to 1600 bar (23,200 psi). The system is managed by a Bosch
EDC 16 engine control unit. Solenoid-operated injectors, mounted
directly in the cylinder head, inject fuel into the combustion chamber
in precise, multiple events (pilot, main, and post injections) per
cycle.
This control enables quieter combustion, reduced emissions, and improved
fuel economy. A low-pressure electric lift pump in the fuel tank
supplies the high-pressure pump. The system includes a fuel temperature
sensor and a water-in-fuel sensor. The fuel filter incorporates a water
separator requiring periodic draining.
The lubrication system is a pressure-fed, full-flow filtration wet-sump
design. A gear-type oil pump is driven directly by the crankshaft. Oil
is drawn from the aluminum oil pan through a pickup tube and screen. The
oil is pressurized and forced through a full-flow, spin-on cartridge oil
filter. From the filter housing, oil flows into the main gallery in the
cylinder block.
It supplies the crankshaft's six main bearings and connecting rod
bearings via drilled passages. A separate feed supplies the cylinder
head, lubricating the camshaft bearings, rocker arms, and hydraulic lash
adjusters. The turbocharger center bearing receives oil from a dedicated
feed line. An oil cooler, integrated into the cooling system, regulates
oil temperature. Oil quality and level are monitored by the engine
management system.
The cooling system is a pressurized, forced-circulation system with a
dual-circuit thermostat for faster warm-up. A centrifugal water pump is
driven by the serpentine accessory belt. Coolant flow is regulated by a
wax-pellet thermostat. The system employs an aluminum radiator with
plastic header tanks. Electric cooling fans provide airflow management.
The turbocharger is a variable geometry turbine (VGT) type, where
movable vanes adjust the effective turbine area to optimize boost
response across the engine speed range. Charge air is cooled by a
front-mounted air-to-air intercooler. The engine incorporates an exhaust
gas recirculation (EGR) system with a cooler to reduce nitrogen oxide
(NOx) emissions. A crankcase ventilation system with an oil separator is
present.
The external dimensions of the OM647 engine are defined by its
inline-five cylinder configuration. Approximate length is 800 mm (31.50
inches). Approximate width is 700 mm (27.56 inches). Approximate height
is 750 mm (29.53 inches). Dimensions vary slightly between longitudinal
passenger car and transverse commercial vehicle installations. The
weight of a complete OM647 engine, with all fluids and standard
accessories, is approximately 230 kg (507 lbs). The cast iron block
forms a substantial portion of this mass.
Engine oil and filter change intervals are extended under the
Mercedes-Benz Flexible Service System (FSS), but a conservative interval
is 15,000 km (9,321 miles) or annually, especially for commercial use.
The fuel filter is a critical maintenance item and must be replaced
every 40,000 km (24,855 miles) or as indicated by the service reminder.
Valve clearance is maintained automatically by hydraulic lifters.
The timing chain and tensioner are designed for the engine's service
life but should be inspected for wear after 300,000 km (186,411 miles).
The accessory drive belt (serpentine belt) should be inspected every
60,000 km (37,282 miles) and replaced at signs of wear. Coolant should
be replaced every 250,000 km (155,343 miles) or 15 years. The EGR valve
should be cleaned periodically to prevent clogging.
All torque values are for clean, dry threads unless specified. Cylinder
head bolts are tightened in a multi-stage angular torque procedure:
initial torque 40 Nm (30 lb-ft), followed by a 90-degree turn, and a
final 90-degree turn. Main bearing cap bolts: 60 Nm (44 lb-ft) plus an
additional 90-degree turn.
Connecting rod cap bolts: 30 Nm (22 lb-ft) plus an additional 90-degree
turn. Crankshaft pulley bolt: 300 Nm (221 lb-ft) plus an additional
90-degree turn. Camshaft sprocket bolts: 100 Nm (74 lb-ft).
High-pressure fuel pump sprocket bolt: 45 Nm (33 lb-ft). Oil drain plug:
40 Nm (30 lb-ft). Oil filter housing: 25 Nm (18 lb-ft).
The Mercedes-Benz OM647 engine saw wide application in both passenger
and commercial vehicles from 2002 until approximately 2009. Primary
passenger car applications include: W211 chassis (E-Class: E 270 CDI).
W203 chassis (C-Class: C 270 CDI). R171 chassis (SLK-Class: SLK 270 CDI
for specific markets). Commercial and van applications are extensive:
T1N chassis (Sprinter 2500/3500 vans and wagons, both North American and
global markets).
It also powered the Volkswagen LT and the Chrysler/Dodge Sprinter in
North America. The OM647 was the dominant diesel engine for the Sprinter
platform during its production run and is noted for its longevity in
high-mileage service. It was succeeded by the V6 OM642 engine in
passenger cars and the four-cylinder OM651 in later Sprinters.
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