Mercedes-Benz OM662 Specifications
| Engine Model: Mercedes-Benz OM662 |
| Engine Type: 4-cycle inline 5-cylinder SOHC 10-valve liquid-cooled diesel |
| Total Displacement: 175.4 cu.in (2.87 L) |
| Rated Engine Power: 95-120 Hp (70-88 kW) at 4000 rpm |
| Fuel System Type: Indirect injection |
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The Mercedes-Benz OM662 is a 2.9-liter, inline-five
diesel engine produced under license by SsangYong in South Korea. Derived from
the Mercedes-Benz OM602 architecture, this powerplant was developed to provide a
robust, mechanically controlled diesel option for SsangYong’s passenger and
light commercial vehicle lineup during the 1990s and early 2000s. The OM662 is
celebrated for its mechanical simplicity, resistance to poor fuel quality, and
extreme durability, with many examples achieving service lives exceeding 500,000
km (300,000 mi) under routine maintenance.
The OM662 retains the core design principles of its Mercedes-Benz predecessor: a
cast iron cylinder block, an aluminum alloy cylinder head, and indirect
injection (IDI) with a Bosch mechanical in-line injection pump. The engine is
offered in both naturally aspirated and turbocharged configurations, with the
turbocharged variant often incorporating an intercooler to increase power output
while maintaining reliability.
The valvetrain employs a single overhead camshaft (SOHC) with two valves per
cylinder, driven by a duplex timing chain that also drives the injection pump.
Hydraulic bucket tappets eliminate the need for manual valve clearance
adjustments, reducing maintenance complexity. The OM662’s robust construction
and mechanical fuel system have made it a favored base for performance upgrades
within enthusiast communities.
The OM662 is a water-cooled, four-stroke diesel engine configured for
longitudinal mounting in rear-wheel-drive and four-wheel-drive vehicle
architectures. The engine is available in naturally aspirated and turbocharged
variants, sharing identical displacement and bore and stroke dimensions.
Engine Type: Inline-5, 4-cycle, water-cooled diesel.
Displacement: 2,874 cc (175.4 cu.in).
Bore and Stroke: 89.0 mm (3.50 in) x 92.4 mm (3.64 in).
Compression Ratio: 22.0:1.
Valvetrain: SOHC, 10-valve (2 valves per cylinder) with chain drive.
Firing Order: 1-2-4-5-3.
Idle Speed: 700 ± 50 rpm.
Maximum Engine Speed: 4,400 rpm (governor limited).
Naturally Aspirated Variant
Aspiration: Naturally aspirated.
Maximum Power: 70 kW (95 Hp) at 4,000 rpm.
Maximum Torque: 192-193 Nm (142 lb-ft) at 2,400-2,600 rpm.
Turbocharged Variant
Aspiration: Turbocharged with intercooler.
Maximum Power: 88 kW (120 Hp) at 4,100 rpm.
Maximum Torque: 250-256 Nm (184-189 lb-ft) at 2,400 rpm.
Turbocharger: Garrett or similar fixed-geometry turbocharger with wastegate.
The cylinder block is constructed from gray cast iron,
a material selected for its exceptional rigidity, vibration-damping properties,
and long-term dimensional stability under high cylinder pressures. The
inline-five configuration provides inherent balance advantages over
four-cylinder engines while maintaining a compact overall length suitable for
passenger vehicle applications. The block features a closed-deck design where
the cylinder bores are fully supported by the water jacket structure at the top
deck surface, providing robust clamping force for the cylinder head gasket.
Cast-in-place cylinder bores are machined directly into the iron casting. The
block incorporates six main bearing webs with two-bolt main bearing caps, an
additional bearing compared to four-cylinder designs to support the longer
crankshaft. The crankshaft is supported by six bearings and is constructed from
forged steel to withstand the elevated cylinder pressures of diesel combustion.
A stamped steel oil pan is sealed to the lower crankcase, providing the oil
reservoir. The block incorporates substantial ribbing around the main bearing
area to minimize flexure under load.
Block Material: Gray cast iron.
Bore Diameter (finished): 89.0 mm (3.50 in).
Main Bearing Caps: Cast iron, two-bolt design.
Cylinder Bore Deformation Limit: 0.05 mm (0.0020 in).
The cylinder head is manufactured from aluminum alloy,
a selection that reduces overall engine mass and improves heat dissipation from
the combustion chambers compared to an all-iron construction. The cross-flow
design positions the intake manifold on one side and the exhaust manifold on the
opposite side. On turbocharged variants, the exhaust manifold is constructed
from cast iron and integrates the turbocharger mounting flange.
The SOHC valvetrain actuates ten valves - two valves per cylinder - through
hydraulic bucket tappets. The hydraulic tappets automatically maintain zero
valve clearance throughout the engine’s service life, eliminating the need for
periodic manual adjustments. The camshaft is driven by a duplex roller chain
from the crankshaft, with an automatic hydraulic tensioner maintaining chain
tension.
The injection pump is driven by a secondary gear or chain take-off from the
camshaft drive system. The pre-chamber combustion system is integrated into the
cylinder head, with each cylinder equipped with a pre-chamber insert and a
pencil-type glow plug. The engine is of interference design; in the event of
timing chain failure or significant timing deviation, valve-to-piston contact
occurs.
Head Material: Aluminum alloy.
Valve Configuration: SOHC, 2 valves per cylinder with hydraulic bucket
tappets.
Valve Diameter (Intake): 42.0 mm (1.65 in).
Valve Diameter (Exhaust): 38.0 mm (1.50 in).
Valve Stem Diameter: 8.0 mm (0.31 in).
Valve Seat Angle: 45 degrees.
The OM662 employs an indirect injection system
utilizing a Bosch mechanical in-line injection pump. The system uses a
pre-chamber located in the cylinder head, into which fuel is injected before
combustion propagates into the main combustion chamber. This design reduces
combustion noise and allows for smooth operation across a wide range of engine
speeds.
The Bosch in-line injection pump is mechanically governed, with a centrifugal
governor controlling fuel delivery based on engine speed and load. The pump
delivers fuel to five individual injection lines that feed nozzle holders
mounted in the pre-chambers. Injection timing is adjusted by rotating the
injection pump relative to the drive gear. A manual or electric fuel shut-off
solenoid provides engine shutdown. The mechanical injection system offers high
tolerance for variable fuel quality and eliminates reliance on electronic
sensors for basic engine operation, contributing to the engine’s reputation for
reliability in demanding conditions.
On turbocharged variants, a boost compensator (aneroid device) is incorporated
into the injection pump to adjust fuel delivery under boost conditions, ensuring
proper air-fuel ratios and preventing excessive smoke output. The turbocharged
variant also utilizes an intercooler to reduce intake air temperature before
combustion.
Injection Type: Indirect injection (pre-chamber).
Injection Pump: Bosch mechanical in-line pump with centrifugal governor.
Injection Pressure (nozzle opening): 11.8-13.0 MPa (1,710-1,890 psi).
Injection Timing: 15-17° before top dead center (dynamic, engine running).
Fuel Requirement: Diesel fuel meeting applicable standards (cetane number 45
minimum).
Turbocharger Boost Compensation: Aneroid device on injection pump.
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 stamped steel oil pan through a mesh
strainer and circulates it through a full-flow, replaceable oil filter before
entering the main oil gallery. A bypass filter is not incorporated on this
engine; the full-flow filter provides adequate contaminant removal for the
specified oil change intervals.
From the main gallery, pressurized oil is distributed to the crankshaft main
bearings, connecting rod bearings, camshaft bearings, hydraulic tappets, timing
chain, and turbocharger bearing housing on turbocharged variants. A pressure
relief valve integrated into the oil pump maintains system pressure within
operational limits to prevent over-pressurization during cold starts.
Oil Type: SAE 15W-40 or 20W-50 (API CF-4, CG-4, or higher).
Oil Capacity (with filter): 7.0-7.5 liters (7.4-7.9 US qt).
Oil Pressure (at 3,000 rpm): 300-400 kPa (43.5-58.0 psi).
Oil Pump Type: Gear-type, crankshaft-driven.
Oil Filter Type: Full-flow, spin-on or cartridge-type.
0The cooling system is a pressurized, liquid-cooled
design employing a cross-flow aluminum or copper-brass radiator with an
engine-driven cooling fan and viscous clutch, supplemented by an electric fan on
some applications. A centrifugal-type water pump, driven by the accessory belt,
circulates coolant through the engine block, cylinder head, turbocharger center
housing (on turbocharged variants), intercooler (on intercooled variants), and
heater core.
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 of the five-cylinder diesel
engine under sustained load conditions.
Coolant Type: Ethylene-glycol based antifreeze with corrosion inhibitors.
Coolant Capacity: 9.0-10.0 liters (9.5-10.6 US qt) (variant dependent).
Thermostat Opening Temperature: 80-85 °C (176-185 °F).
Thermostat Full-Open Temperature: 95 °C (203 °F).
Radiator Cap Pressure: 100-120 kPa (14.5-17.4 psi).
Water Pump Type: Centrifugal, accessory belt-driven.
Turbocharger System (Turbocharged Variant): The engine
is equipped with a fixed-geometry turbocharger, supplied by Garrett or a
comparable manufacturer. The turbocharger features a water-cooled bearing
housing to prevent oil coking after engine shutdown. Boost pressure is regulated
by an internal wastegate actuator set to open at approximately 0.7-0.9 bar
(10.2-13.1 psi). An air-to-air intercooler is mounted in front of the radiator
to reduce intake air temperature before entering the engine, increasing air
density and reducing thermal load.
Intake System: Cast aluminum or composite plastic intake manifold with
individual runners per cylinder. The naturally aspirated variant uses a single
inlet from the air cleaner housing. The turbocharged variant routes compressed
air from the turbocharger through an intercooler before entering the intake
manifold. The intake system incorporates an air cleaner housing with a dry-type
paper filter element.
Exhaust System: Cast iron exhaust manifold with individual runners. On naturally
aspirated variants, the manifold collects into a single downpipe. On
turbocharged variants, the manifold mounts the turbocharger directly. The
exhaust system incorporates a catalytic converter on later variants.
Timing Drive: A duplex roller chain drives the camshaft and injection pump from
the crankshaft sprocket. An automatic hydraulic tensioner maintains chain
tension. The timing chain is designed for extended service life with no
specified replacement interval under normal operating conditions.
Overall Length: 860 mm (33.9 in)
Overall Width: 630 mm (24.8 in)
Overall Height: 760 mm (29.9 in)
Dry Weight (complete engine): 210-230 kg (463-507 lb)
Oil Change Interval: 10,000 km (6,200 mi) under normal
driving conditions; 5,000 km (3,100 mi) under severe conditions. Oil Filter
Change: At every oil change. Timing Chain Inspection: No scheduled replacement;
inspect for noise at each service interval. Engine Coolant Replacement: 40,000
km (25,000 mi) or 2 years.
Glow Plug Inspection: Check at each major service; replace as required. Drive
Belt (Accessory) Inspection: Every 10,000 km (6,200 mi) for tension, cracking,
and glazing. Air Filter Replacement: 20,000 km (12,500 mi) or as indicated by
inspection. Fuel Filter Replacement: 20,000 km (12,500 mi).
Valve Clearance: Hydraulic bucket tappets; no adjustment required. Idle Speed
Adjustment: 700 ± 50 rpm; adjust via idle speed screw on injection pump.
Injection Timing Adjustment: Inspect as required; timing marks on injection pump
drive and front cover.
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).
Main Bearing Cap Bolts (M12 x 1.5): 90-100 Nm (66-74 lb-ft).
Connecting Rod Cap Bolts (M10 x 1.25): 50-55 Nm (37-41 lb-ft).
Camshaft Bearing Cap Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Intake Manifold Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Exhaust Manifold Nuts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Turbocharger Mounting Nuts (M8 x 1.25): 25-30 Nm (18-22 lb-ft).
Glow Plugs: 20-25 Nm (15-18 lb-ft).
Oil Pan Bolts (M6 x 1.0): 8-10 Nm (71-89 lb·in).
Water Pump Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Timing Chain Tensioner (M14 x 1.5): 50-60 Nm (37-44 lb-ft).
Crankshaft Pulley Bolt (M18 x 1.5): 280-300 Nm (207-221 lb-ft).
Flywheel / Drive Plate Bolts (M10 x 1.25): 70-75 Nm (52-55 lb-ft).
Injection Pump Drive Gear Nut (M12 x 1.5): 45-50 Nm (33-37 lb-ft).
The Mercedes-Benz OM662 engine, produced under license
by SsangYong, was utilized across a range of SsangYong passenger vehicles, light
commercial vehicles, and licensed variants produced in other markets.
SsangYong Musso: Naturally aspirated (2.9 D) and turbocharged (2.9 TD) variants.
SsangYong Korando (KJ series): Naturally aspirated and turbocharged variants.
SsangYong Rexton (RX290): Turbo-intercooled variant in early model years.
SsangYong Istana / Mercedes-Benz MB100 / MB140: Licensed van applications.
TagAZ Tager / Road Partner: Russian-assembled variants of Korando and Musso.
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