Mercedes-Benz OM 617 diesel engine

Mercedes Benz
OM 617
Manufacturer:	Mercedes Benz
Production period:	1974-1992
Style:	Line five-cylinder
Engines:	3.0 liters (3000 cc)  3.0 liters (2998 cc)
Previous model:	none
Successor:	Mercedes-Benz OM602

The OM-617 is a five-cylinder in - line engine from Daimler-Benz . The diesel engine came in 1974 in the Mercedes-Benz 240 D 3.0 ( "dash-eight" , W 115) on the market. It is derived from the four-cylinder engine OM 616 and differs from this only by the additional cylinder . Thanks to the modular system, it shares the pistons and connecting rods with the OM 616 (240 D) . In the development was Ferdinand Piech , grandson of Ferdinand Porsche and subsequent CEO of Volkswagen AG , a major role. He operated from 1972 an engineering firm in Stuttgart and later built five-cylinder engines also at Audi .

Turbo variants 

As early as May 1976, Hans Liebold's first project lead was the first world record rides with a modified C111 / 2 with OM 617 ATL and an output of approx. 140 kW in Nardò (Italy). The average speeds reached were around 250 km / h.

In May 1978, once again set long-distance world records with the OM 617 ATL with the newly built record vehicle C 111/3, whose performance had since been increased to 170 kW. In combination with the extremely aerodynamic body of the C 111/3 with a c _w value of 0.18, the average speed could be increased to over 320 km / h.

With the T-model (estate) of the mid-range 300 TD turbodiesel from the 123 series , the turbo engine came in a version with 92 kW (125 hp) for sale. The engines achieve a torque of 250 Nm.

The turbocharging was offered shortly before in 1978 in the 300 SD Turbo ( Series 116 ) as standard for the American market. This approach corresponds to a pattern that has often been tried and tested at technology and series changes at Daimler-Benz: a new technology is being introduced in a limited market segment (USA), and if it proves to be successful, the technology will soon be introduced in other markets or other series , This strategy minimizes cost issues in the event of difficulties, such as reliability and warranties.

Due to the different conditions of use. Vehicles driven on highways for a long time at maximum speed and then parked with partially red-hot turbos suffered damage to the turbocharger: the immediate shutdown of the engine meant that the turbine shaft was not equipped with lubrication. The dark glowing afterglow of the high volumes of exhaust gas at full load then heats up the entire loader together with the turbine shaft and the oil, with the result that the oil in the shaft bearing coked and blocked the loader.Afterwards, instructions were given in the operating instructions that after full throttle, the turbo diesel engines must first be "cooled down" or they must not be parked directly from the high load condition, but only after a few minutes of cooling caster at lower load.

OM 617.950 (Turbo OM 617 A, A = exhaust driven charger) in 1979:

• Bore 90.9 mm, stroke 92.4 mm, displacement 2998 cm³
• Compaction 21.5: 1
• Power 85 kW (115 hp) at 4000 rpm
• Torque 250 Nm at 2400 rpm
• Maximum speed 5200 / min

OM 617.952 (Turbo OM 617 A) in 1982:

• Bore 90.9 mm, stroke 92.4 mm, displacement 2998 cm³
• Compaction 21.5: 1
• Power 92 kW (125 hp) at 4350 rpm
• Torque 250 Nm at 2400 rpm
• Maximum speed 5200 / min

This turbocharged engine was the first diesel engine to be suitable for entry into the bodies of the S-Class and the middle class coupe - Daimler-Benz was concerned with complying with the fleet's fuel consumption figures prescribed by US governments. So they were the models 300 SD (S-Class Diesel) and 300 CD (diesel coupe) arise, the first ( S-Class W 116 , Coupe C 123 ) and second body versions ( S-Class 126 series , coupe C 124 ) were sold only in the US.

In these first diesel turbo engines for Mercedes cars injection-cooled pistons were used. They are the first production engines in the world to have slide bearings fromthe manufacturer Glyco , in which the steel carrier layer, the bronze bearing layer and the electroplated coating were then applied by vacuum in a top supporting hard layer by sputtering . Since then, this technology has been in production use in many high-performance engines due to its hardness and wear properties. Tuning tests on diesel engines previously failed often with engine damage too low piston cooling and too weak bearings of the crankshaft, which did not withstand the higher combustion pressures.

Development and problems 

From the first series engines were partly with problems in the casting quality of the now to the fifth cylinder longer engine housing. Likewise, there were initially problems with the turbos - the high pressures on the crankshaft bearing led to various damage. Daimler-Benz then used (for the first time) plain bearings with a sputtering layer for these engines .

Daimler-Benz used in this engine, for the first time in passenger car diesel engines, crankshafts, which - after forging in one plane - are still "twisted". The twisting is a twisting of the crankpins to achieve a uniform ignition offset of 144 degrees on the five-cylinder. (For six-cylinder shafts, four of the six crank pins are twisted 60 degrees, which is cheaper than the pin offset of five cylinders.) For this purpose, the blank of the five-cylinder shaft after forging and deburring in another forging stroke by means of a special die four of the cranks each by 36 Degree from the forging level hydraulically lifted or lowered. Thus, the five-cylinder crankshaft is a considerably more complex manufactured component compared to a four-cylinder shaft.

The first turbos were sometimes not able to cope with high continuous loads at high outside temperatures, if, for example, after high load travel. B. on the highway at a service area of ​​the engine immediately, that is turned off without a cooling phase and then coking in the glowing turbo oil remaining at the turbocharger shaft - a user error that can still provide today for turbocharger damage.

Both the large first-generation naturally aspirated and the turbos, with their large capacity of three liters, were significantly different from the old Diesel reputation of economy. At approx. 10 l / 100 km, the 59 kW variant and the turbos (here also due to the standard automatic transmission) can hardly be moved. Only the 65-kW variant with manual transmission, especially with the available from 1982 five-speed gearbox, brought the three-liter diesel with less than 9 l / 100 km on fuel consumption, which are well below the small gasoline engines of the time.

Since the late 1990s, another advantage of this generation of diesel is striking: the OM 617, like its four-cylinder sister engines and the subsequent generation of diesel engines, is ideally suited for use with vegetable oil. With the original injectors (Bosch DN0SD220), the cold start properties are relatively poor. However, it is easy to mount the Vorstrahldüsen (DN0SD261 / 265/314) from the W 124 , which also improves the cold start. Regular exhaust gas testing proves that the turbidity levels still quite high in this generation can be significantly reduced by using plant oil.

Compared to more modern diesel engines it is noticeable that the OM 617, like its model siblings, is still quite rough. The five-cylinder engine can not keep up with the following engine type OM 603 in terms of comfort and fuel consumption , especially in the series where it was used before the six-cylinder three-liter engine ( US models of the S-Class W126 ) . Advantage of the older engine type, however, is its relatively insensitivity to damage to the cylinder head gasket, since the casting material of the engine housing and the cylinder head in the OM 617 is still identical, whereas the successor has a cylinder head made of aluminum with a consequently differing expansion behavior.

Use in Models 

• W 115 240 D 3.0
• W 116 300 SD Turbodiesel (for US export)
• W 123 300 D
• W 123 T 300 TD
• C 123 300 CD Diesel and Turbodiesel (US export)
• W 123 300 D Turbodiesel (US export)
• W 123 300 TD Turbodiesel (also home market)
• W 126 300 SD Turbodiesel (US-Export)
• Puch / Mercedes G 300 GD
• Mercedes-Benz T1 (209 D, 309 D, 409 D)
• C111 Type II (prototypes and experimental vehicles)

Data 

• Bore : 91 mm
• Stroke : 92.4 mm
• Displacement : 3005 cm³
• Compression ratio : 21: 1
• Power: 59  kW (80  hp ) at 4000 rpm
• Torque: 172 Nm at 2400 rpm
• Maximum speed: 5100 / min

In August 1979, with the same stroke, the bore was slightly reduced by 0.1 mm and the performance increased by higher compression, a modified cylinder head(steeper camshaft , other atria) by 10%:

• Bore 90.9 mm
• Displacement: 2998 cc
• Compaction 21.5: 1
• Power 65 kW (88 hp) at 4400 rpm
• Torque unchanged 172 Nm at 2400 / min