The Mercedes M104 Engine Manual

The Mercedes M104 Engine Manual. Mercedes-Benz first launched the M104 engine to the automobile industry in 1989. Mercedes produced the M104 series for a decade until it was replaced by the M112 in 1999. The M104 engine was last utilized in the Mercedes 140; nevertheless, the M104 engine and its derivatives have been used in approximately 40 distinct vehicles over its lifetime. Because Mercedes needed a compact, economical engine for their Vito van, these six-cylinder engines were derived from the Volkswagen VR6. However, Mercedes did not cease updating the M104 and expanding its use for a variety of new applications.

The M104 engines are available in five different displacement sizes, including AMG variants. The Mercedes M104 is available in a variety of engine sizes, beginning with the 2.8 L and progressing to the 3.4L and 3.6L AMG models. The M104 is regarded as one of Mercedes’ most dependable engines. Many drivers say that vintage straight-6s are dependable daily drivers for up to 200,000 miles with no major issues.

However, not every M104 will reach that milestone, and many will necessitate meticulous repairs and upkeep. Furthermore, parts for many of the numerous models that use the M104 may be difficult to come by. The Mercedes M104 engine, on the other hand, has a lot of advantages. However, not every engine is flawless. Throughout this guide, we will examine some of the advantages and disadvantages of the M104 series, as well as its overall impact on the automobile market.

The Mercedes M104 Engine Manual

Mercedes M104 Engine Specifications

The Mercedes M104 engine specifications are as follows:

The Mercedes M104 Engine Manual

The obvious distinctions between these engines are the gradual rise in displacement and power output. Mercedes used the M104 engines in a variety of models, including the ones mentioned below, until the AMG conversions were made. Except for the original Volkswagen VR6 adaption used in the Vito vehicle, all of these engines are straight-six. Check out our earlier guide on the M112 V6 for more information on older historic Mercedes V6 engines.

Turbocharger kits were available from multiple aftermarket manufacturers for both the M103 and M104, considerably increasing power. A limited batch of 75 turbocharged M104 engines was eventually sold straight from the Mercedes dealership Hughes of Beaconsfield. Turbocharger kits for the M103 and M104 engines are still available from various manufacturers, primarily in Asia and Europe.

The engines are all built with a cast-iron block and an aluminum head. Many Mercedes drivers love the toughness of these M104s. Regardless of their simplicity, the M104 engines are noted for their dependability as well as great power and performance.

What Vehicles Make Use of the Mercedes M104?

The Mercedes M104 engine can be found in the models listed below:


  • 1989–1992 C124 300 CE-24
  • 1989–1993 R129 300SL-24
  • 1990–1993 W124 300 E-24
  • 1990–1993 S124 300 TE-24
  • 1987—1993 Spyder 036i 3.0-24V Isdera

2.8L (M104.94)

  • W202 C280
  • W210 E280
  • 1993–1994 W124 280E, 300E 2.8
  • 1994–1996 W124 E280
  • 1993–1998 W140 300 SE 2.8, S 280
  • W124 SsangYong Chairman H CM500S 1997-2004
  • 2003-2006 SsangYong Rexton I RX 280 Y200

3.2L (M104.99)


  • 1993–1994 W124 300 E, 320 E
  • 1994–1996 W124 E 320
  • 1995–1997 W210 E320
  • W140 300 SE, 300 SEL, 1991-1993
  • 1993–1999 W140 S320
  • 1994–1998 R129 SL 320
  • W463 G320


  • From 1997 to 2017, he served as Chairman.
  • From 1996 through 2006, Korando
  • 2007-2014 Kyron
  • 1993–1999 Musso
  • Rexton Y200 (2001-2006)
  • Rodius (2004-2013)

AMG 3.4L:

  • 1988-1993 W124
  • SL 3.4 AMG (rare) 1988-1993
  • AMG 3.6L:
  • W202 C36 AMG
  • W124 C36 AMG
  • W210 C36 AMG
  • G36 AMG

The M104 engines were used in 36 different vehicles by five different automakers, including Mercedes-Benz, Roewe, Heuliz, Status & Class, and SsangYong.

Reliability of the Mercedes M104 Engine

The Mercedes M104 engine, with correct maintenance and care, can be exceptionally reliable and have an astonishingly long lifespan. The M104 series is created with the goal of reaching 400,000 miles on paper. Many drivers report reaching the 200,000-mile mark with no major repairs required. However, it is important to highlight that these milestones are subject to a variety of factors. Most engines, including the M104, require regular maintenance and the use of high-quality oil.

Only a few significant design defects and recurring concerns may be detected across the M104’s many varied applications. This engine series’ dependability is still regarded as good, especially when compared to other Mercedes and luxury automobile engines of the time. Because many M104 engines do not have major difficulties until they reach 200,000 miles, we would have to evaluate the M104’s overall reliability as very good.

Certain difficulties, however, are frequent in these straight-six engines. Overheating and oil leaks appear to be recurring annoying issues for many drivers. Mass airflow sensors are likewise prone to malfunction, eventually necessitating a total replacement. Furthermore, in severe or freezing temperatures, these engines become extremely vulnerable.

M104 Common Engine Issues

The Mercedes M104 engine is well-rounded and dependable. However, certain early design defects exist, which contribute to some of the issues discussed below. It’s important to note that not every M104 driver will encounter these issues; however, we found them to be common enough to be considered the key issues to watch out for. Many of the concerns listed below can be avoided with proper maintenance and prompt response to needed repairs. It is also worth noting that these problems are more likely to arise in places with significant seawater concentrations. Saltwater, in particular, can accelerate erosion. This deterioration will most likely be observed first in your brake pads and rotors, eventually leading to the failure of various electrical components. As previously indicated, these engines are also susceptible to extremely cold temperatures.

Regardless, let’s look at some of the most serious problems that can develop in the Mercedes M104 engine. For starters, the engine is prone to overheating, which is usually caused by the main cooling fan failing. Many versions that use the M104 are also known to have malfunctioning mass airflow sensors. Furthermore, due to various design issues that we shall discuss further below, oil leaks can be a bothersome issue for the M104. Again, it is crucial to note that these issues will not affect every Mercedes M104 engine. These are merely the most often reported problems with the M104 series. Nonetheless, let us now delve deeper into these issues and look at some of their most typical symptoms.

Overheating MBZ M104 Engine

One of the most serious problems with the M104 series is engine overheating. The cooling fan clutch is most likely a cause of numerous M104 engine problems. Unfortunately, engine overheating can be caused by a multitude of factors, and Mercedes M104 users frequently experience trouble determining the root cause of this problem. Furthermore, the main cooling fan can frequently fail completely, which can lead to a variety of other issues with the M104 if not quickly repaired. Finally, water pumps and serpentine belts may eventually need to be replaced to eliminate any other sources of overheating.

Coolant leakage and radiator problems are also among the most prevalent M104 engine failures. It is also critical to immediately examine your thermostat if you are having engine overheating difficulties. The following are symptoms of engine overheating:

  • Ticking or pounding sounds coming from the engine compartment
  • Emissions of steam or smoke from the engine compartment
  • Coolant leaks/puddles forming beneath the car
  • Engine power reduction
  • The hot hood
  • Failure of the Mass Airflow Sensor

Many Mercedes M104 drivers have reported issues with the mass airflow sensor, particularly those who have logged more miles. Mass airflow sensors determine whether or not an engine is receiving adequate airflow. Engine power and performance will suffer as a result of insufficient airflow, and catastrophic engine damage may occur. Dirty or clogged airflow sensors will not accurately detect airflow and will generate error messages if they fail. Driving with a defective mass airflow sensor does not cause severe engine damage. However, without a functional MAS, many engine problems might worsen to the point of significant damage due to the engine’s inability to receive appropriate airflow.

Among the symptoms of mass airflow sensor failure are:

  • The exhaust emits a dark/heavy smoke.
  • Idle time
  • decreased fuel efficiency
  • Poor acceleration/surging, as well as hesitancy
  • Difficult/difficult start

Related : The Guide to the Mercedes M112 V6 Engine

Oil Leaks in a Mercedes M104

Many engines have recurring problems with oil leaks. Unfortunately, the Mercedes M104 engine is a member of this group as well. These oil leaks and high oil consumption might be caused by a variety of factors. However, many of the problems associated with oil leaks in the Mercedes M104 can be avoided by using high-quality oil and performing regular oil changes. However, once any engine reaches hundreds of thousands of kilometers, oil leaks and excessive oil consumption can become a major issue.

Throughout the M104 engine, certain gasket seals and some rear sealants are prone to leaks. Furthermore, worn valve stems are a major cause of annoying leaks and increased oil usage. However, because of the multitude of causes for oil leaks, it is critical to identify the root cause and correct these issues as soon as possible before more serious engine damage happens.

Symptoms of Mercedes M104 oil leaks may also include:

  • Smoke coming from the engine compartment
  • Overheating of the engine
  • Oil pools form beneath the automobile
  • The odor of burning oil

Summary of the Mercedes M104 Engine Guide

The M104 engine series had a long career due to its remarkable durability and power-to-performance ratio. These engines are well-known for their long-lasting construction and ability to achieve high mileage without costly or extensive repairs. However, not every engine is flawless in its design. The M104s are sensitive to extremely cold temperatures. Furthermore, several drivers complain oil leaks and high oil use. Furthermore, engine overheating can be a problem in older M104 engines, particularly those that have not been well maintained or driven vigorously. Finally, as previously said, the mass airflow sensor in various M104 models appears to fail far too frequently. Despite these issues, we maintain our assessment of the Mercedes M104 engine’s reliability as very good.

To summarize, the Mercedes M104 engine has few obvious problems. However, the Mercedes M104’s fuel system, sensors, and computers can be considered weak points, owing to flaws that emerge over time and wear. But, once again, no engine is faultless or constructed of stone. As a result, for their size and age, these engines have an excellent mix of endurance and power, especially when compared to similarly-sized luxury engines of the time. As a result, it’s simple to see why many enthusiasts regard the M104 as one of Mercedes’ legendary classic engines.