Mercedes-Benz OM605 Specifications
| Engine Model: Mercedes-Benz OM605 |
| Engine Type: 4-cycle inline 5-cylinder DOHC 20-valve turbocharged liquid-cooled diesel |
| Total Displacement: 152.4 cu.in (2.49 L) |
| Rated Engine Power: 113-150 Hp (84-110 kW) at 4600 rpm |
| Fuel System Type: Electronic injection pump |
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The Mercedes-Benz OM605 engine is an
inline-five cylinder, turbocharged diesel powerplant from the
Mercedes-Benz 600-series diesel family. Introduced in 1993, this engine
was designed to offer a balance of performance, refinement, and fuel
efficiency for mid-size and executive vehicles. It succeeded the OM602
engine, with primary advancements including a dual overhead camshaft
(DOHC) valvetrain, four valves per cylinder, and an updated Bosch VP
electronic diesel injection pump.
The OM605 is constructed with a cast iron cylinder block and an aluminum
alloy cylinder head. It established a reputation for exceptional
durability, strong torque delivery, and tunability, becoming a favored
base for performance diesel conversions. This engine family represents
the peak of Mercedes-Benz's indirect injection diesel technology before
the transition to common-rail direct injection systems.
Engine family: Mercedes-Benz OM605.
Engine type: Inline-five cylinder, four-stroke diesel cycle,
turbocharged.
Displacement: 2497 cc (152.4 cubic inches).
Bore: 87.0 mm (3.425 inches).
Stroke: 84.0 mm (3.307 inches).
Compression ratio: 22.0:1.
Maximum power output: 113 Hp (84 kW) at 4600 rpm for early versions
(OM605.910); 129 Hp (96 kW) at 4600 rpm for later versions
(OM605.912/OM605.962); 150 Hp (110 kW) at 4000 rpm for the OM605.970.
Maximum torque output: 162 lb-ft (220 Nm) at 2800 rpm for early
versions; 199 lb-ft (270 Nm) at 2600-3000 rpm for later versions; 229
lb-ft (310 Nm) at 2000 rpm for the OM605.970.
Firing order: 1-2-4-5-3.
Engine orientation: Longitudinal.
Aspiration: Turbocharged with wastegate; some versions incorporate an
air-to-air intercooler.
Fuel type: Diesel fuel.
Recommended oil grade: SAE 10W-40 or 15W-40, meeting Mercedes-Benz
specification 228.1 for diesel engines. Oil capacity: 6.5 liters (6.9
U.S. quarts), including filter.
Coolant capacity: 9.0 liters (9.5 U.S. quarts).
The cylinder block is a single, rigid casting from grey cast iron. Its
design provides high strength and excellent acoustic damping properties,
which are beneficial for diesel operation. The block incorporates five
cylinder bores arranged in line. The crankshaft is supported by six main
bearings, a configuration that ensures smooth operation and counters the
inherent vibrations of a five-cylinder layout.
The crankshaft is a forged steel component, hardened for longevity. Main
bearing caps are cast iron and secured with two vertical bolts each.
Connecting rods are forged from steel, featuring a robust I-beam design.
Pistons are aluminum alloy, with a deep combustion bowl in the crown to
facilitate the indirect injection combustion process. Each piston is
fitted with three rings: two compression rings and one 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). This four-valve design
improves airflow and combustion efficiency compared to older two-valve
diesel heads. Valve actuation is via bucket-type tappets with hydraulic
lash adjusters, providing automatic valve clearance compensation.
The camshafts are driven by a single-stage duplex roller chain from the
crankshaft. Chain tension is maintained by a hydraulic tensioner. Intake
valves have a head diameter suitable for high volumetric efficiency.
Exhaust valves feature sodium-filled stems on some high-output versions
to manage increased thermal loads. Valve seats are hardened to withstand
diesel combustion.
The fuel system is an electronically controlled, distributor-type
injection pump system (Bosch VP). The system is an evolution of
mechanical pump technology, incorporating an electronic control unit
(ECU) for precise management of injection timing and quantity. The main
component is a Bosch VP 44 or VP 37 rotary distributor pump, driven by
the engine's timing gear.
This pump generates high fuel pressure and distributes it sequentially
to each cylinder's injector via high-pressure steel lines. The injectors
are pintle-type, mounted in a pre-chamber (swirl chamber) in the
cylinder head. A vacuum-operated fuel cut-off valve controls engine
shutdown. An electric lift pump in the fuel tank supplies diesel to the
injection pump. Injection timing is adjusted by the ECU based on engine
speed, load, and coolant temperature.
The lubrication system is a pressure-fed, full-flow filtration wet-sump
design. A gear-type oil pump is driven by a chain from the crankshaft.
Oil is drawn from the steel oil pan through a pickup tube and screen.
The oil is then pressurized and forced through a full-flow, replaceable
cartridge-type oil filter. From the filter housing, oil enters the main
gallery in the cylinder block. It supplies the crankshaft's six main
bearings and connecting rod bearings via drilled passages.
A separate gallery feeds the cylinder head, lubricating the camshaft
bearings, hydraulic lash adjusters, and the timing chain tensioner. The
turbocharger center bearing receives oil from a dedicated feed line. Oil
pressure is monitored by a switch and a gauge sender unit.
The cooling system is a pressurized, forced-circulation system. A
centrifugal water pump is driven by a V-belt from the crankshaft pulley.
Coolant circulates through the cylinder block and head, regulated by a
wax-pellet thermostat. The system employs an aluminum radiator with a
plastic header tank. An electric auxiliary fan supplements engine
cooling, triggered by a thermoswitch.
The turbocharger is a wastegate-controlled unit, with compressed air
routed through an air-to-air intercooler on later, more powerful
variants (denoted by ".962" or ".970" engine codes) to increase charge
density. The glow plug system uses a dedicated controller to heat the
pre-chambers for cold starting. An exhaust gas recirculation (EGR)
system is present for emissions control on certain market versions.
The external dimensions of the OM605 engine are consistent with an
inline-five cylinder configuration of its displacement. Approximate
length is 750 mm (29.53 inches). Approximate width is 650 mm (25.59
inches). Approximate height is 750 mm (29.53 inches). These dimensions
include the turbocharger, injection pump, and other ancillary
components. The weight of a complete OM605 engine, with all fluids and
standard accessories, is approximately 220 kg (485 lbs). The cast iron
block contributes significantly to this mass.
Engine oil and filter change intervals are 10,000 km (6,214 miles) or
annually under normal service conditions. The fuel filter is a critical
service item and should be replaced every 20,000 km (12,427 miles) or as
specified. Valve clearance is maintained automatically by hydraulic
lifters, requiring no scheduled adjustment.
The timing chain and tensioner are designed for long service life but
should be inspected for wear after 250,000 km (155,343 miles). The
accessory drive belt(s) should be inspected every 20,000 km and replaced
if worn. Coolant should be drained, flushed, and refilled every 4-5
years. Glow plugs should be tested and replaced as a set if failures
occur.
All torque specifications assume clean, dry threads unless otherwise
noted. Cylinder head bolts are tightened in a specific multi-stage
sequence: initial torque 40 Nm (30 lb-ft), followed by a 60-degree turn,
and a final 60-degree turn.
Main bearing cap bolts: 60 Nm (44 lb-ft). Connecting rod cap bolts: 50
Nm (37 lb-ft) plus an additional 30-degree turn. Crankshaft pulley bolt:
400 Nm (295 lb-ft). Camshaft sprocket bolts: 65 Nm (48 lb-ft). Fuel
injection pump sprocket bolt: 65 Nm (48 lb-ft). Oil drain plug: 40 Nm
(30 lb-ft). Oil filter housing cap: 25 Nm (18 lb-ft).
The Mercedes-Benz OM605 engine was installed in a range of mid-size and
executive models from 1993 to 1999. Primary applications include: W124
chassis (E-Class: E 250 Diesel, E 250 Diesel Turbo). S124 chassis
(E-Class Wagon). W210 chassis (E-Class: E 250 Diesel, E 250 Diesel
Turbo). C124 chassis (E-Class Coupe). R129 chassis (SL-Class: SL 250
Diesel for specific markets).
The engine was also used in the W463 chassis (G-Class: G 250 TD) for
commercial/military customers. The high-output OM605.970 variant was
found in the W210 E 250 Turbodiesel. Production ceased with the phasing
out of indirect injection technology in favor of the new common-rail
OM612 and OM647 engines.
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