Mercedes-Benz OM617

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Mercedes-Benz OM617 engine
300SD OM617.jpg
Manufacturer Mercedes-Benz
Production 1974-1991
Configuration Straight-5
Displacement 2998 cc
Cylinder bore 91.0 mm
90.9 mm
Piston stroke 92.4 mm
Cylinder block alloy Cast iron
Cylinder head alloy Cast iron
Valvetrain Chain driven SOHC 10 valve
Compression ratio 21:1
Turbocharger No (OM 617.91x 617.93x)
Yes (OM 617.95x)
Fuel system Indirect injection
Management Bosch M pump
Bosch MW pump
Fuel type Diesel fuel
Oil system Wet sump
Cooling system Liquid
Successor OM602

The OM617 engine family is a straight-5 diesel automobile engine from Mercedes-Benz used in the 1970s and 1980s. It is a direct development from the straight-4 OM616. It was sold in vehicles from 1974 to 1991. The OM617 is considered to be one of the most reliable engines ever produced with engines often reaching over 1,000,000 km without being rebuilt and is one of the key reasons for Mercedes' popularity in North America in the 1980s, as it was powerful and reliable compared to other automotive diesels of the time. It is also a very popular choice for the use of alternative fuels, mainly straight or waste vegetable oil and biodiesel, although the use of these fuels may cause engine damage over time if not processed properly before use.

OM617 Naturally Aspirated[edit]

Essentially a OM616 with an extra cylinder, it debuted in 1974 with the W115 chassis. Bore was 91.0mm and stroke 92.4mm. It was originally 80 PS (79 hp/59 kW.) Bosch MW inline injection pumps were used, which had flyweight governors and vacuum shutoff. Previous engines had used pneumatic governors, and "gorilla knob" to start and shut off the engine. The North American engines had ADA device equipped pumps which limited fuel at high altitudes to prevent smoking with less dense air. New engine blocks after the .910 had rear mounted oil filter housings, with a combined full flow and bypass filter element. In August 1978 the precombustion chamber was updated to be similar to the new OM617A design for more swirl and more efficient combustion. The engine capacity was lowered to 2998 cc to satisfy engine displacement tax laws in Europe by changing the bore to 90.9 mm. September 1979 saw a new camshaft with greater valve lift let air and exhaust gases have less resistance. Power output rose to 88 PS (87 hp/65 kW). Torque remained at 172 Nm (126 lb/ft.)@ 2400 rpm.[1] In November 1980 the MW style injection pump was replaced with the M type for non-North American engines. Engines were equipped with series wired loop type glow plugs up until 1980 when replaced by the much more reliable pencil type plugs (these had been already used in the OM617A since 1978). Vehicles sold to the North American market had exhaust gas recirculation equipment fitted.


Canister style oil filter at bottom front of engine. Power output was 80 hp (59 kW) @ 4000 rpm and torque was 172 Nm(126 lb/ft.) @ 2400 rpm.[2]



This was introduced with the W123 series. Power originally was 80 hp (59 kW) @ 4000 rpm, torque 172 Nm(126 lb/ft.) @ 2400 rpm. From September 1979 - 87 hp (65 kW) @ 4400 rpm, torque 172 Nm (126 lb/ft.)@ 2400 rpm.



This was an adaption of the .912 to the T1 chassis. It had a downward facing oil filter housing.

OM617.931 and OM617.932

This engine was adapted from the .912 to fit the G Class[3], main difference being oil pan changes.


OM617A Turbocharged[edit]

The year 1976 saw the engine adapted to use a turbocharger. This 190hp OM617LA was fitted to the C111-IID test vehicle, and set 16 world land speed and endurance records at the Nardo test facility in Italy. In 1978 the engine was upgraded again to 230hp and installed in the C111-IIID and broke 9 further records [4]. Modifications for production engines included oil squirters to cool the underneath of the pistons; pistons with oil passages; stronger connecting rods; sodium filled valve stems and a stronger nitride-hardened crankshaft. Also an uprated oil pump with separate chain drive was fitted as the turbocharger lubrication required higher flow. Bosch MW injection pumps were calibrated for greater fuel output and fitted with an ALDA device which prevented overfueling until the turbocharger had begun to provide boost pressure. Pencil glow plugs were provided on all OM617A engines.


In 1978, the OM617.950 was mated with the Mercedes-Benz W116 to produce the North American market-only 300SD, the world's first production turbodiesel sedan. These engines pre-dated the introduction of tighter emissions laws, so were not fitted with EGR. Power originally was 111 hp / 82 kW @ 4200 rpm, torque 228 Nm (168 lb/ft.)@ 2400 rpm. From October 1979 - 121 hp / 89 kW @ 4350 rpm, torque 230 Nm (170 lb/ft.)@ 2400 rpm.[5]



The .951 was introduced for 1981 and displaced 2998 cc, using a 90.9 mm bore and 92.4 mm stroke. Power originally was 121 hp / 89 kW @ 4350 rpm, torque 230 Nm (170 lb/ft.)@ 2400 rpm. From August 1984 - 125 hp / 92 kW @ 4350 rpm, torque 250 Nm (184 lb/ft.)@ 2400 rpm.[6] Vehicles sold to the North American market had EGR equipment fitted.



The .952 is identical to the .951 apart from minor changes to fit the North American 123 chassis. It was also fitted to the European market W123 wagon, the 300TD. This was the only turbocharged OM617 fitted to a European W123. Power originally was 121 hp / 89 kW @ 4350 rpm, torque 230 Nm (170 lb/ft.)@ 2400 rpm. From October 1982 - 125 hp / 92 kW @ 4350 rpm, torque 250 Nm (184 lb/ft.)@ 2400 rpm.[7] Vehicles sold to the North American market had EGR equipment fitted.


See also[edit]


  1. ^ "Mercedes-Benz W123 300D Archive". 
  2. ^ "Mercedes-Benz W115 240D 3.0 Archive". 
  3. ^ "Mercedes-Benz W460 300GD Archive". 
  4. ^ "Mercedes-Benz C 111 History". 
  5. ^ "Mercedes-Benz W116 300SD Archive". 
  6. ^ "Mercedes-Benz W126 300SD Archive". 
  7. ^ "Mercedes-Benz W123 300D Turbo Archive".