Mercedes-Benz OM617 Specifications
| Engine Model: Mercedes-Benz OM617 |
| Engine Type: 4-cycle inline 5-cylinder SOHC 10-valve liquid-cooled diesel |
| Total Displacement: 182.9-183.4 cu.in (2.99-3.01 L) |
| Rated Engine Power: 80-125 Hp (59-93 kW) at 4200 rpm |
| Fuel System Type: Indirect injection |
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The Mercedes-Benz OM617 is an inline-five, water-cooled
diesel engine produced between 1974 and 1991, widely regarded as one of the most
durable internal combustion engines ever manufactured. Developed as an extension
of the four-cylinder OM616, the OM617 holds the distinction of being the world’s
first five-cylinder passenger car diesel engine. Its reputation for exceptional
longevity - with countless examples surpassing 620,000 miles (1,000,000 km)
without major overhaul - established Mercedes-Benz’s benchmark for diesel
reliability and durability throughout the 1970s and 1980s.
The OM617 family encompasses both naturally aspirated and turbocharged variants,
with the turbocharged OM617A introduced in 1978 as the world’s first production
turbodiesel passenger car engine. The engine’s architecture is characterized by
a cast iron cylinder block and cylinder head, a single overhead camshaft (SOHC)
driven by a robust timing chain, two valves per cylinder, and a Bosch mechanical
indirect injection system using pre-combustion chambers.
The turbocharged variants incorporated specific reinforcements including
oil-cooled pistons and a nitrided crankshaft to withstand elevated thermal and
mechanical loads. The OM617 powered a wide range of Mercedes-Benz passenger
cars, the G-Class off-road vehicle, and commercial transporters throughout its
seventeen-year production run.
The OM617 is a four-stroke, water-cooled, naturally aspirated or turbocharged
diesel engine configured for longitudinal mounting in rear-wheel-drive and
four-wheel-drive vehicle architectures. The inline-five configuration provides
inherent primary balance while delivering greater displacement than a
four-cylinder within a compact package.
Type: inline-five, SOHC water-cooled diesel.
Redline: 5,000 rpm.
Firing Order: 1-2-4-5-3.
Naturally Aspirated (Early OM617.910)
Displacement: 3,005 cc (183.4 cu.in).
Bore and Stroke: 91.0 mm (3.58 in) x 92.4 mm (3.64 in).
Compression Ratio: 21.0:1.
Maximum Power: 59 kW (80 Hp) at 4,000 rpm.
Maximum Torque: 172 Nm (127 lb-ft) at 2,400 rpm.
Naturally Aspirated (Late OM617.912,
OM617.931)
Displacement: 2,998 cc (182.9 cu.in).
Bore and Stroke: 90.9 mm (3.58 in) x 92.4 mm (3.64 in).
Compression Ratio: 21.0:1.
Maximum Power: 65 kW (88 Hp) at 4,400 rpm.
Maximum Torque: 172 Nm (127 lb-ft) at 2,400 rpm.
Turbocharged (OM617A: OM617.950, OM617.951,
OM617.952)
Displacement: 2,998 cc (182.9 cu.in).
Bore and Stroke: 90.9 mm (3.58 in) x 92.4 mm (3.64 in).
Compression Ratio: 21.5:1.
Maximum Power: 82-93 kW (110-125 hp) at 4,200-4,350 rpm.
Maximum Torque: 231-250 Nm (170-184 lb-ft) at 2,400 rpm.
The cylinder block is manufactured from gray cast iron
using a high-strength alloy, a material chosen for its exceptional rigidity,
wear resistance, and vibration-damping properties essential for diesel engine
durability. The block features a closed-deck design, with the water jacket fully
enclosed at the top deck surface, providing maximum cylinder head gasket
clamping force and resistance to bore distortion under high compression
pressures.
The inline-five configuration incorporates six main bearing webs with the
crankshaft supported at six points - a main bearing between each cylinder and at
both ends - providing superior crankshaft support compared to four-cylinder
designs.
Pressed-in, replaceable cast iron cylinder liners are employed, allowing for
engine rebuilding through liner replacement and overboring. The liners are of
the wet type, with direct coolant contact on their outer surfaces for efficient
heat transfer. The block incorporates a gear-driven injection pump mounting pad
on the front left side and provisions for the vacuum pump driven by the
camshaft.
Block Material: Cast iron.
Liner Type: Replaceable, pressed-in wet liners.
Bore Diameter (early): 91.0 mm (3.58 in).
Bore Diameter (late): 90.9 mm (3.58 in).
Main Bearing Caps: Cast iron, two-bolt design with six main bearings.
Liner Protrusion above Block Deck: 0.07-0.12 mm (0.0028-0.0047 in).
The cylinder head is manufactured from cast iron,
matching the thermal expansion characteristics of the block to ensure reliable
head gasket sealing across the wide temperature range of diesel operation. The
head utilizes a cross-flow design with the intake manifold on the left side and
the exhaust manifold on the right side.
The combustion system employs indirect injection (IDI) with individual
pre-combustion chambers - swirl chambers - for each cylinder, formed by steel
inserts pressed into the cylinder head. These chambers provide a highly
turbulent environment for fuel-air mixing before combustion propagates into the
main cylinder, enabling smooth, quiet diesel operation.
The SOHC valvetrain operates ten valves - two per cylinder - via roller rocker
arms. The camshaft is driven by a double-roller timing chain from the
crankshaft, with a hydraulic tensioner maintaining optimal chain tension. Valve
clearance is set manually using adjustment screws on the rocker arms, a system
requiring periodic maintenance. The turbocharged OM617A incorporates
sodium-filled exhaust valves on certain variants for enhanced heat dissipation.
Head Material: Cast iron.
Combustion Chamber: Indirect injection with steel pre-combustion chamber
inserts.
Valve Configuration: SOHC, 2 valves per cylinder with roller rocker arms.
Valve Diameter (Intake): 40.0 mm (1.57 in).
Valve Diameter (Exhaust): 39.0 mm (1.54 in).
Valve Stem Diameter: 9.0 mm (0.35 in).
Valve Seat Angle: 45 degrees.
Glow Plug Type: Series-wired loop type (early); pencil type (late).
The OM617 employs a Bosch mechanical indirect injection
fuel system. A Bosch in-line injection pump - M-series or MW-series depending on
variant - is mounted on the left side of the cylinder block and driven by the
engine’s gear train. The injection pump uses individual plungers and barrels for
each cylinder, delivering precisely metered fuel through high-pressure steel
injection lines to nozzle-type injectors mounted in the cylinder head. A
mechanical governor regulates fuel delivery based on engine speed and load, with
an integrated cold-start device that advances injection timing when the engine
is cold.
The turbocharged OM617A incorporates an aneroid compensator (boost compensator)
on the injection pump, which adjusts fuel delivery in response to turbocharger
boost pressure to prevent excessive smoke during acceleration. A manual primer
pump is integrated into the fuel system to facilitate bleeding air after filter
changes. A fuel filter with an integrated water separator is mounted in the fuel
supply line.
Injection Type: Mechanical indirect injection.
Injection Pump: Bosch in-line type (M or MW series).
Injection Timing: 24-26 degrees before top dead center (static).
Injection Pressure (nozzle opening): 11.8-13.7 MPa (1,711-1,987 psi).
Fuel Requirement: Diesel fuel with minimum cetane number of 45.
Glow Plug Voltage: 6.5-12.0 V depending on variant.
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 a stamped steel or cast aluminum oil pan
through a mesh strainer and circulates it through a full-flow, replaceable oil
filter before entering the main oil gallery. A bypass valve allows oil flow to
continue if the filter becomes restricted.
The turbocharged OM617A incorporates several enhancements: oil-cooled pistons
with oil jets (piston squirters) that direct a continuous spray of oil to the
underside of each piston crown, a larger-capacity oil cooler, and a nitrided
crankshaft with enhanced surface hardness. A water-cooled oil cooler is mounted
externally on the oil filter housing to stabilize oil temperature under
sustained high-load operation.
Oil Type: Diesel-rated SAE 15W-40 or 10W-30 (API CC, CD, or higher).
Oil Capacity: 6.5-8.6 liters (6.9-9.1 US qt) depending on oil pan configuration.
Oil Pressure (at 3,000 rpm): 294-441 kPa (42.6-64.0 psi).
Oil Pressure (at idle): 98 kPa (14.2 psi) minimum.
Oil Pump Type: Gear-type, crankshaft-driven.
Piston Cooling Jets: Turbocharged variants only.
The cooling system is a pressurized, liquid-cooled
design engineered to manage the thermal load of a diesel engine under sustained
operation. A large-capacity cross-flow copper or aluminum radiator with a
viscous-driven mechanical fan provides cooling capacity. A centrifugal-type
water pump, driven by the timing chain, circulates coolant through the cylinder
block, cylinder head, 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 efficiently.
The system is designed to provide uniform cooling across all five cylinders,
minimizing thermal distortion of the cast iron components.
Coolant Type: Ethylene-glycol based antifreeze with corrosion inhibitors.
Coolant Capacity: 9.0-12.0 liters (9.5-12.7 US qt) depending on radiator.
Thermostat Opening Temperature: 80-86 °C (176-187 °F).
Radiator Cap Pressure: 88-108 kPa (12.8-15.7 psi).
Water Pump Type: Centrifugal, timing chain-driven.
| Intake and Exhaust Systems |
Intake System: Air is drawn through a dry-type paper
element air filter before entering the intake manifold. The naturally aspirated
variants use a cast iron intake manifold; turbocharged variants use a cast
aluminum manifold.
Exhaust System: Cast iron exhaust manifold with individual runners collecting
into a single outlet. The turbocharged variant incorporates the turbocharger
mounting flange into the manifold casting.
Turbocharger (OM617A): Single-scroll turbocharger with
a fixed geometry turbine housing. The turbocharger is mounted on the exhaust
manifold and provides boost pressure of approximately 0.7 bar (10.2 psi). The
system incorporates a boost pressure gauge in the instrument cluster on
passenger car applications.
Timing Drive: A double-roller timing chain drives the camshaft and injection
pump. The chain is tensioned by a hydraulic tensioner and operates in a
pressurized oil bath within the timing cover. The timing chain system is
designed for the engine’s service life with regular maintenance.
Overall Length: 850 mm (33.5 in)
Overall Width: 600 mm (23.6 in)
Overall Height: 750 mm (29.5 in)
Dry Weight (complete engine): 220-235 kg (485-518 lb)
Oil Change Interval: 5,000 km (3,000 mi) under normal
driving conditions; shorter intervals under severe conditions. Oil Filter
Change: At every oil change. Timing Chain: Inspection for stretch and tensioner
function every 100,000 km (60,000 mi). Chain replacement may be required at
higher mileages. Engine Coolant Replacement: 60,000 km (40,000 mi) or 2 years.
Fuel Filter Replacement: 20,000 km (12,000 mi) or as indicated by water
separator inspection. Fuel Water Separator Drain: Every 5,000 km (3,000 mi) to
remove accumulated water. Glow Plug Inspection: 60,000 km (40,000 mi) for
resistance and heating performance. Valve Clearance Adjustment: Inspect and
adjust every 20,000 km (12,000 mi). Intake and exhaust: 0.10 mm (0.004 in) cold
with engine at operating temperature.
Drive Belt (Accessory) Inspection: Every 10,000 km (6,000 mi) for tension,
cracking, and glazing. Air Filter Replacement: 30,000 km (18,000 mi) or as
indicated by restriction indicator. Injection Pump Timing: Should be verified
after any service affecting timing chain alignment using dynamic timing
equipment or dial indicator method. Valve Adjustment Procedure: Clearance is set
by loosening the rocker arm lock nut and turning the adjustment screw. The
engine must be at operating temperature.
Cylinder Head Bolts (M12 x 1.75), 1st pass: 50 Nm (37
lb-ft).
Cylinder Head Bolts (M12 x 1.75), 2nd pass: 80 Nm (59 lb-ft).
Cylinder Head Bolts (M12 x 1.75), 3rd pass: 100 Nm (74 lb-ft).
Main Bearing Cap Bolts (M12 x 1.75), 1st pass: 50 Nm (37 lb-ft).
Main Bearing Cap Bolts (M12 x 1.75), final pass: 80 Nm (59 lb-ft).
Connecting Rod Cap Bolts (M10 x 1.25), 1st pass: 40 Nm (30 lb-ft).
Connecting Rod Cap Bolts (M10 x 1.25), final pass: 65 Nm (48 lb-ft).
Camshaft Bearing Cap Bolts (M8 x 1.25): 20-25 Nm (15-18 lb-ft).
Rocker Arm Shaft Bolts (M10 x 1.25): 40-45 Nm (30-33 lb-ft).
Intake Manifold Nuts (M8 x 1.25): 20-25 Nm (15-18 lb-ft).
Exhaust Manifold Nuts (M8 x 1.25): 20-25 Nm (15-18 lb-ft).
Glow Plugs: 15-20 Nm (11-15 lb-ft).
Oil Pan Bolts (M8 x 1.25): 20-25 Nm (15-18 lb-ft).
Water Pump Bolts (M8 x 1.25): 20-25 Nm (15-18 lb-ft).
Injection Pump Mounting Nuts (M10 x 1.25): 35-40 Nm (26-30 lb-ft).
Injection Line Nuts: 20-25 Nm (15-18 lb-ft).
Crankshaft Pulley Bolt (M18 x 1.5): 300-350 Nm (221-258 lb-ft).
Flywheel Bolts (M10 x 1.25): 40 Nm (30 lb-ft).
The Mercedes-Benz OM617 engine was utilized across an
extensive range of Mercedes-Benz passenger cars, off-road vehicles, and
commercial transporters throughout its seventeen-year production life. Variants
were tailored for specific vehicle platforms with distinct oil pan
configurations, engine mounts, and accessory drives.
Mercedes-Benz W115 240D 3.0: 1974-1976 (OM617.910 naturally aspirated).
Mercedes-Benz W123 300D, 300CD, 300TD: 1976-1985 (OM617.912 naturally aspirated;
OM617.951, OM617.952 turbocharged from 1981).
Mercedes-Benz W116 300SD: 1978-1980 (OM617.950 turbocharged; first production
turbodiesel passenger car).
Mercedes-Benz W126 300SD, 300SDL: 1981-1985 (OM617.951, OM617.952 turbocharged).
Mercedes-Benz G-Class W460, W461 300GD: 1979-1991 (OM617.931, OM617.932
naturally aspirated with specialized oil pan).
Mercedes-Benz TN / T1 Transporter (209 D, 309 D, 409 D): 1977-1986 (OM617.913
naturally aspirated).
Mercedes-Benz W123 300D (Mexican market): Produced into the early 1990s.
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